nuove tendenze in ortopedia canina e felina

Transcription

66SCIVAC congress_CDokk._07) SCIVAC/SIOVET congress 06/09/10 15.46 Pagina 1
SIOVET
SOCIETÀ ITALIANA
DI ORTOPEDIA VETERINARIA
Richiesto accreditamento
SOCIETÀ FEDERATA ANMVI
NUOVE TENDENZE IN ORTOPEDIA CANINA E FELINA
66° CONGRESSO NAZIONALE SCIVAC
BOLOGNA
BolognaCongressi
17-18 SETTEMBRE 2010
SCIVAC CONGRESS
PROCEEDING
Organizzato da
Soc. Cons. a r.l.
Azienda con sistema qualità certificato ISO 9001:2008
66° CONGRESSO NAZIONALE SCIVAC • BOLOGNA, 17-18 SETTEMBRE 2010
RELATORI
BRIAN BEALE
ANTONIO POZZI
DVM, Dipl ACVS,
Texas, USA
DMV, MS, Dipl ACVS,
Florida, USA
Alla laurea in medicina veterinaria, conseguita a Milano nel 1997, segue una intership in medicina e chirurgia dei piccoli animali presso l’Università dell’Ohio dal 2001
al 2002 e un Residency in chirurgia dei piccoli animali che termina nel 2005. Si diploma all’American College of Veterinary Surgery nel 2006. Nel 2007, ha co-fondato il
Comparative Orthopaedic Biomechanical
Laboratory all’Università della Florida, coinvolgendo l’Università di Medicina, di Medicina Veterinaria e di Ingegneria. Dal 2006
è Assistant Professor in chirurgia ortopedica veterinaria e Adjunct Professor in chirurgia ortopedica (umana) all’Università
della Florida. I suoi interessi clinici sono la
chirurgia mini-invasiva ortopedica, la chirurgia del ginicchio e la chirurgia protesica.
Ha ricevuto numerose awards per i suoi lavori sulla biomeccanica delle osteotomie tibiali, sui trattamenti meniscali e sulla fissazione delle fratture per via mini-invasiva.
Si laurea presso l’Università della Florida
nel 1985. Nel 1985 completa un internship presso il Friendship Hospital for Animals in Washington, D.C. Nel 1991 prende il diploma all’American College of Veterinary Surgeons. È stato Assistant Professor in chirurgia all’Università della Florida per poi raggiungere la Gulf Coast Veterinary Specialists nel 1992. Il dr. Beale è
Adjunct Assistant Professor presso il Texas
A&M College of Veterinary Medicine.
SORREL LANGLEY-HOBBS
MA, BVetMed Dipl SAS(O),
Dipl ECVS, MRCVS,
Cambridge (UK)
Si Laurea al Royal Veterinary College di Londra nel 1990. Dopo esservi rimasta un anno
come stagista, ha esercitato per tre anni la
libera professione per poi rientrare a Londra
e completare una Residency in Ortopedia
nei piccoli animali. Ha ottenuto l’RCVS in
chirurgia dei piccoli animali (Ortopedia) nel
1997 per poi diplomarsi all’ECVS nel 1999.
Ha trascorso sei mesi come docente di Chirurgia presso l’Università della Pennsylvania
nel 1998 ed è attualmente University Surgeon in Ortopedia dei piccoli animali e Direttore dell’istituto di Chirurgia dell’Università di Cambridge. Si occupa di tutti gli
aspetti della chirurgia ortopedica dei piccoli
animali, ma ha un particolare amore per
l’ortopedia felina. Recentemente è stata coautore di un libro di testo di Chirurgia Felina ortopedica e delle malattie muscoloscheletriche con Katja Voss e Pierre Montavon e pubblicato da Elsevier, Saunders.
RICO VANNINI
Dr Med Vet, Dipl ECVS,
Regensdorf, CH
Laureato in Medicina Veterinaria a Zurigo.
Ha compiuto un residency presso l’Ohio
State University. Attualmente lavora presso
la sua clinica per piccoli animali a Zurigo
(Bessy Clinic). È diplomato ECVS e membro
attivo di AO-VET International. È autore di
numerose pubblicazioni nel campo della
chirurgia dei piccoli animali e dei cani da
lavoro. Si occupa principalmente di chirurgia dei piccoli animali.
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PROGRAMMA SCIENTIFICO
VENERDÌ, 17 SETTEMBRE 2010
8.00
9.00
9.30
10.00
10.30
11.00
11.30
12.00
12.30
13.00
14.00
14.30
15.00
15.45
16.45
17.00
Chairman: Massimo Petazzoni
Registrazione Congressuale
Displasia del gomito: quali sono le nuove opzioni chirurgiche e quali
i loro margini di successo?
Brian Beale (USA)
Lesioni parziali del legamento crociato craniale, un argomento davvero
così controverso?
Brian Beale (USA)
Come migliorare la visualizzazione del menisco
Antonio Pozzi (USA)
Perle e trabocchetti nelle osteotomie tibiali (TPLO, TTA, CWTO)
Antonio Pozzi (USA)
PAUSA CAFFÈ ED ESPOSIZIONE COMMERCIALE
Come riuscire a riparare con successo le lussazioni mediali della rotula
in cani di piccola taglia e nei gatti
Brian Beale (USA)
Lussazione mediale della rotula e rottura del legamento crociato
nei cani di taglia piccola e grande
Antonio Pozzi (USA)
Trucchi e trabocchetti nelle tecniche di stabilizzazione extracapsulare
del ginocchio
Antonio Pozzi (USA)
PAUSA PRANZO ED ESPOSIZIONE COMMERCIALE
Chairman: Filippo Maria Martini
Zoppie posteriori nel gatto: che cosa è se non è una frattura
né un ascesso?
Sorrel Langley-Hobbs (UK)
Zoppie anteriori nel gatto: che cosa è se non è una frattura
o un ascesso?
Le fratture nel gatto. Quiz
PAUSA CAFFÈ ED ESPOSIZIONE COMMERCIALE
State of the Art Lecture
L’esito delle lesioni traumatiche del ginocchio. Cosa sappiamo oggi?
Stefan Lohmander (S)
Termine della giornata
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SABATO, 18 SETTEMBRE 2010
Chairman: Carlo Maria Mortellaro
9.00 La visita ortopedica - Consigli e suggerimenti per una diagnosi
di successo
Rico Vannini (CH)
9.30 Il trattamento conservativo delle fratture e il contenimento esterno
10.00 Principi di artrodesi
10.30 Complicazioni dell’artrodesi
Rico Vannini (CH)
11.00 PAUSA
CAFFÈ ED ESPOSIZIONE COMMERCIALE
11.30 Planning nel trattamento delle fratture nel gatto
Rico Vannini (CH)
12.00 Trattamento della rottura del legamento crociato nei cani di razza
di piccola taglia e nei gatti
Rico Vannini (CH)
12.30 Fratture radio ulnari nei cani di razza Toy
Rico Vannini (CH)
13.00 PAUSA
PRANZO ED ESPOSIZIONE COMMERCIALE
Chairman: Aldo Vezzoni
14.00 Artrotomia a guida artroscopica… cavalca l’onda del futuro
Brian Beale (USA)
14.30 Lussazione mediale della rotula in cani di grossa taglia…
qual è la differenza?
Brian Beale (USA)
15.00 Riduzione mini-invasiva delle fratture
Antonio Pozzi (USA)
15.30 Infezioni ortopediche… cosa c’è di nuovo?
Brian Beale (USA)
16.00 Perché questo caso di frattura è finito male?
Brian Beale (USA)
16.30 PAUSA
CAFFÈ ED ESPOSIZIONE COMMERCIALE
17.00 State of the Art Lecture
Ricostruzione cartilaginea con ACI (Autologous Chondrocyte
Implantation) e MACI (Matrix-induced Autologous Chondrocyte
Implantation): hanno resistito alla prova del tempo?
Tim W.R. Briggs (UK)
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COMITATO SCIENTIFICO DEL
66° CONGRESSO NAZIONALE SCIVAC
Bruno Peirone, Med Vet, Dr Ric, Torino
Aldo Vezzoni, Med Vet, SCMPA,
Dipl ECVS, Cremona
COORDINATORE SCIENTIFICO
CONGRESSUALE
Fulvio Stanga, Med Vet, Cremona
SEGRETERIA SCIENTIFICA
Monica Villa
Tel. +39 0372 403504
E-mail: [email protected]
COMMISSIONE SCIENTIFICA
SCIVAC 2007-2010
Massimo Baroni, Med Vet, Dipl ECVN,
Monsummano Terme (PT)
Davide De Lorenzi, Med Vet,
Dipl ECVCP, Padova
Giorgio Romanelli, Med Vet,
Dipl ECVS, Milano
Fulvio Stanga, Med Vet, Cremona
SEGRETERIA MARKETING,
SPONSOR E AZIENDE ESPOSITRICI
Ilaria Costa
Tel. +39 0372 403538
SEGRETERIA ISCRIZIONI
Paola Gambarotti
Tel. +39 0372 403508
Fax +39 0372 457091
CONSIGLIO DIRETTIVO SCIVAC 20072010
Dea Bonello
Presidente
Massimo Baroni Presidente Senior
Federica Rossi
Vice Presidente
Marco Bernardini Segretario
Bruno Peirone
Consigliere
Guido Pisani
Tesoriere
Alberto Crotti
Consigliere
ORGANIZZAZIONE CONGRESSUALE
E.V. Soc. Cons. a r.l.
Via Trecchi, 20 - 26100 CREMONA (Italia)
6
LECTURES ABSTRACTS
These proceeding report faithfully all abstracts
provided by the authors
who are responsible of the content of their works.
The abstracts are listed in alphabetical order by surname
and then in chronological
order of presentation.
Brian S. Beale
DVM, Dipl ACVS, Texas (USA)
Displasia del gomito: quali sono le
nuove opzioni chirurgiche e quali
i loro margini di successo?
Venerdì, 17 Settembre, ore 9.00
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B.S. Beale
Elbow dysplasia - what are the new surgical options
and are they successful?
Brian S. Beale, DVM, Dipl ACVS
Texas (USA)
INTRODUCTION
Canine elbow dysplasia is a commonly reported thoracic limb disorder. Elbow dysplasia is characterized by an
abnormal development of the elbow joint coupled with characteristic pathological changes of the medial compartment. Pathologic changes are associated with the coronoid process and humeral condyle. Pathology of the
medial coronoid is typified by subchondral bone microfracture and fragmentation as well as cartilage erosion
secondary to incongruence as seen. Many hypotheses have been formulated about the etiopathogenesis of the
pathologic changes including radioulnar incongruence. The histologic and ultrastructural appearance of FCP
is consistent with mechanical failure and subsequent unsuccessful fibrous repair. Fragmented medial coronoid
process (FCP) is the most common manifestation of elbow dysplasia. Osteoarthritis is also typically found in
most patients with FCP and the amount of cartilage damage can vary greatly. The prevailing belief is that radioulnar incongruence is secondary to improper growth of the radius and ulna during maturation. The result
is malalignment of the articular surfaces where the medial coronoid is subject to high mechanical loads and microfracture or fragmentation. Another theory suggests fragmentation and microfracture of the medial coronoid
may be secondary to mechanical overload associated with contraction of the biceps brachii/brachialis muscle
complex. Arthroscopy confirms fragmentation of the medial coronoid adjacent to the radial head without the
presence of visible cartilage erosion in some dogs, supporting this hypothesis. Acute trauma to the medial coronoid process can also cause fracture of the MCP. Surgical treatment is believed to provide superior results to
conservative management by most surgeons. The outcome following surgery appears to be improved in the
past decade, partly due to new and improved surgical techniques. Surgical techniques that have improved the
treatment of elbow arthroscopy include arthroscopy, abrasion arthroplasty, microfracture, subtotal coronoidectomy, biceps tendon release and sliding humeral osteotomy (SHO).
ARTHROSCOPY
Arthroscopy has revolutionized the surgical
treatment of FCP for two main reasons- improved assessment of the condition and decreased morbidity associated with the treatment. The arthroscope provides an enhanced view of the anconeal process,
trochlear notch, lateral coronoid process, radial head, ulnar incisure, humeral condyle
and medial coronoid process due to its magnification and ability to view anatomical
structures from an optimal perspective.
Arthroscopy gives the surgeon the ability to Fragments of the medial coronoid process develop near the radial head. Fragments
better evaluate the number and position of may be non-displaced (A) or displaced (B).
fragments within the joint. The surgeon
can also assess congruity by evaluating cartilage wear patterns and noting the relative
positions of the radial head, medial coronoid process, ulnar incisure, trochlear notch and anconeal process.
Treatment of the condition can also be done with arthroscopic observation. This allows the surgeon to be
more precise and less invasive. Fragment removal, abrasion arthroplasty, microfracture, subtotal coronoidectomy and biceps tendon release can be performed with arthroscopic assistance. Arthroscopic evaluation has
very low morbidity which allows treatment of multiple joints at the same time.
FRAGMENT REMOVAL
Removal of fragments and necrotic bone of the medial coronoid process is recommended. Arthroscopic or
arthroscopic-assisted removal is recommended because of its low morbidity and increased precision. Removal
of the fragment from the medial coronoid process can occasionally be accomplished by simply grasping the
loose fragment with a grasping forcep while the medial joint space is opened as valgus pressure is applied by
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ORTOPEDIA
CANINA
the surgical assistant. This is typically not possible without causing iatrogenic damage to the cartilage of the
medial coronoid process, radial head and medial coronoid process. Several practical tips can facilitate removal
of the fragment. Sometimes the fragment is visible, but is clearly not dislodged. Occasionally the fissure line associated with the fragment is not initially visible. Use the probe to gently probe and rub the region of the medial coronoid process. This maneuver will usually reveal the margins of the fragment. A small curette, probe
or banana knife is used to try to elevate the fragment to facilitate its removal. Fragment removal can be more
effectively performed after removal a small portion of bone and cartilage from the medial coronoid process just
cranial to the fragment. Chondomalacia and microfractures of the subchondral bone are typically found in this
region. A curette, hand burr or power shaver can be used to remove these damaged tissues, creating more space
and improved access to remove the main fragment. The fragment may have to be removed in multiple pieces,
either due to the fragility of the fragment or due to the sheer size of it. Fragments having necrotic bone and
microfractures will often break into smaller fragments when grasped to remove them. In this case the fragment
is removed by passing the grasper multiple times until all the fragments are removed. Alternatively, a power
shaver can be used to remove small multiple fragments. If the fragment is large and comprised of dense bone,
it may be too large to grasp and remove in one piece. The fragment can be broken into smaller pieces using a
small osteotome or power burr. Multiple fragments are often found. Inspect the region cranial to the radial head
carefully using a probe. Many patients have multiple loose fragments and they usually are found cranial to the
main fragment adjacent to the radial head. Some fragments may have a soft tissue attachment which prevents
simple withdrawal of the fragment form the joint. Large soft tissue attachments should be severed from the
fragment using a banana knife, aggressive shaver blade or small forceps. Small soft tissue attachments can often be broken down by simply twisting the fragment 360-720° while it is grasped.
OSTEOARTHRITIS
The severity of osteoarthritis is best evaluated using an arthroscope. The arthroscope can be inserted into
the joint using ypical arthroscopic portals or through an arthrotomy incision to improve the surgeon’s view.
Osteoarthritis can be treated arthroscopically using hand instruments or a motorized shaver. The goal of the
treatment is debridement of necrotic cartilage, removal of sclerotic bone, neovacularization, and recruitment
of pluripotential mesenchymal cells. Cartilage debridement is accomplished using a hand burr, hand curette or motorized shaver. The exposed subchondral bone can be treated using abrasion arthroplasty
or micropick technique.
Abrasion arthroplasty
To perform abrasion arthroplasty, insert a hand burr or preferentially
a power shaver burr through an instrument portal or arthrotomy. Either method will produce significant bone debris that can clog the
egress portal and impede visualization, therefore it is important to
monitor and maintain the flow of fluid through the joint during this
procedure. Spin the burr to remove subchondral bone over the area of
the lesion. Check for resulting bleeding frequently by stopping inflow
of fluid and ensuring adequate outflow to decrease the pressure in the
joint. When bleeding is observed diffusely from the lesion bed, lavage
the joint to remove the remaining bone debris and close routinely.
A hand curette can also be used for surface abrasion if the subchondral bone is not too sclerotic. Similar principles should be used as described above. The curette is also useful to contour the edge of the
cartilage defect; an effort should be made to leave the edges of the articular cartilage perpendicular to the subchondral bone.
Microfracture
To perform microfracture, insert an appropriately angled micropick
into the joint and press the tip against the subchondral bone surface.
Have an assistant tap the pick handle once or twice. The pick should
be held securely to avoid gouging the surface and adjacent healthy
cartilage. Apply the micropick diffusely across the diseased area and
check for resulting bleeding frequently by stopping inflow of fluid
and ensuring adequate outflow. When bleeding is observed diffusely
from the lesion bed, lavage the joint to remove the remaining bone
debris and close routinely.
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A motorized shaver is used for abrasion arthroplasy to remove necrotic cartilage and bone.
Microfracture is used to treat the exposed subchondral bone after removal of necrotic cartilage.
B.S. Beale
SUBTOTAL CORONOIDECTOMY
Subtotal coronoidectomy was introduced by Fitzpatrick as a
means of treating FCP by removing the majority of the medial
coronoid process (MCP).
The rationale of removing a large portion of the MCP is the discovery of microfactures within all regions of the subchondral
bone of the MCP in affected dogs.
Fitzpatrick found positive results in dogs treated with this
method if they met the proper criteria. Subtotal coronoidectomy
can be performed via a standard medial arthrotomy, arthroscopic–assisted arthrotomy or arthroscopically.
BICEPS TENDON RELEASE
The biceps/brachialis muscles constitute a large muscular
complex. The anatomic origin and insertion of the biceps and
brachialis muscles are such that the muscular complex exerts
considerable force on the medial compartment of the elbow.
The force exerted by the biceps is continuous since it is a pen- The ulnar component of the biceps tendon can be renate muscle with central tendon. More importantly, because leased from its insertion near the MCP. This is thought
the insertion of the biceps/brachialis complex is at the ulnar to release load in the medial compartment and conflict
tuberosity, a large polar (rotational) moment is exerted at the between the radial head and medial coronoid process.
cranial segment of the medial coronoid. The magnitude of the
polar moment is a product of the moment arm (distance from
the ulnar tuberosity to the tip of the coronoid) multiplied by
the force created by the biceps/brachialis muscular complex.
The polar moment rotates and compresses the craniolateral
segment of the medial coronoid against the radial head. The
compressive force is medial to lateral transverse to the long
axis of the coronoid. A compressive force generates internal
shear stress at an oblique angle to the applied compressive
force. In this situation, maximal internal shear stress would be
oblique to the long axis of the coronoid. Under the right circumstances, the polar moment and resultant compressive
force produced by the biceps/brachialis complex may produce
sufficient internal shear stress to exceed the material strength
of the cancellous bone in the craniolateral segment of the meThe ulnar insertion of the biceps tendon can be released
dial coronoid.
The result would be microfracture/fragmentation adjacent to arthroscopically in an attempt to decrease loads placed
the radial head at an oblique angle to the long axis of the me- across the medial compartment of the elbow.
dial coronoid. Interestingly, microfracture/fragmentation of
the coronoid seen clinically is in the craniolateral segment of
the medial coronoid adjacent to the radial head. This location corresponds to the plane of maximal shear
stress generated by the compressive force exerted by the polar moment produced by contracture of the biceps/brachialis complex.
Hulse first reported the use of biceps tendon release as an adjunctive treatment for dogs affected by FCP.
Fitzpatrick also reported on the clinical use of this procedure and found encouraging results. The technique is used to lessen the conflict between the radial head and MCP. This conflict is theorized to be a cause
of microfracture of the subchondral bone of the MCP and cartilage erosion of the radial head and MCP.
Following removal of fragments, the tension placed on the MCP can potentially be decreased by cutting the
ulnar component of the tendon and transferring it to a more lateral location. This tendon can actually be released at the elbow or shoulder. At the present time, it is unknown where the optimal release site is. Side effects and complications appear to be very low. Dogs typically use the leg with little lameness following biceps tendon release.
SLIDING HUMERAL OSTEOTOMY
Schulz et al. introduced a humeral osteotomy technique designed to shift the weightbearing loads from the medial to the lateral compartment of the elbow. Fitzpatrick reported on its clinical use in a series of clinical patients
and found improvement in lameness in dogs having cartilage erosion of the medial compartment fo the elbow
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and fragmentation of the MCP. A
medial approach to the humerus is
made and a mid-humeral transverse osteotomy is performed. The
distal humeral segment is transposed
or slid to a more medial location, thus
shifting load towards the lateral compartment during ambulation. A specially designed SHO plate and locking screws made by New Generation Products are used to stabilize
the bone. The plate has a step in the
middle of the plate to accommodate a
repeatable amount of medial sliding.
The plate comes in several sizes with
varying steps. Early outcome results
are encouraging. Most dogs show improvement in lameness following
SHO even though the technique has
been initially proposed for dogs having severe degenerative changes associated with elbow dysplasia.
References are available
upon request.
Sliding humeral osteotomy is a reasonable
surgical option for dogs having cartilage
erosion in the medial compartment of the
elbow. The distal aspect of the humerus is
translocated to a more medial position,
shifteing weightbearing loads to the lateral compartment of the elbow.
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Brian S. Beale
Lesioni parziali del legamento
crociato craniale, un argomento
davvero così controverso?
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B.S. Beale
Partial tears of the cranial cruciate ligament is it really that controversial?
Texas (USA)
WHAT IS A PARTIAL TEAR?
Partial tears of the cranial cruciate ligament (CrCL) are commonly diagnosed in dogs. Partial tears may involve the craniomedial band, caudolateral band or both. Partial tears may or may not be associated with
gross instability. Many patients with early partial tears of the CrCL do
not have demonstrable cranial drawer or cranial tibial thrust. These patients are commonly referred to as stable partial tears. Other dogs have
variable amounts of instability in flexion. These patients are commonly
referred to as unstable partial tears. Some dogs with partial tears have
grossly intact fibers that have stretched (plastic deformation) and are
nonfunctional. Instability found with this type of partial tear is similar
to that seen with a complete tear; cranial drawer and cranial tibial thrust
are evident. It is important to realize that osteoarthritis and meniscal
damage can occur with any type of partial tear. Early diagnosis and A partial tear of the insertion of the craniomeprompt treatment of partial CrCL tears gives the patient the best op- dial band of the CrCL (a) can be accurately diportunity of avoiding these painful and debilitating sequelae. The CrCL agnosed and treated arthroscopically.
should be examined under magnification using an arthroscope or magnifying loops. Many partial tears can not be adequately seen with the
naked eye. In addition, early treatment may help prevent the progressive of a partial tear to a complete tear. Most
partial tears of the CrCL are thought to progress to a complete tear over time if left untreated.
TREATMENT OF PARTIAL TEARS OF THE CrCL
Several options can be considered for treatment of partial tears of the CrCL in dogs. Factors to consider when
choosing a method of treatment include severity of the tear, amount of instability, condition of the meniscus,
patient size and expected activity level of the patient. Options to consider include a procedure that neutralizes
cranial tibial thrust (TPLO, TTA, TTO), extracapsular prosthetic ligament repair, intracapsular ligament repair, and physical rehabilitation exercise. Surgical debridement of the ligament is also a factor to be considered.
Some surgeons debride only the torn fibers, some debride the entire ligament and others debride none of the
torn fibers. Studies are currently in progress to evaluate the need and outcome following ligament debridement
or preservation in patients with partial CrCL tears. Arthroscopy can be combined with any of the above stabilization techniques in an effort to reduce patient morbidity and increase accuracy of treatment. At the present time, no method of treatment has been shown to be superior for treatment of partial CrCL tears in dogs.
EXPECTED OUTCOME
Tibial Plateau Leveling Osteotomy (TPLO) is frequently performed to treat the cruciate-deficient stifle and
is recommended by many surgeons to treat dogs having partial CrCL tears in an effort to preserve the ligament as a result of reduced strain on the ligament. Second-look arthroscopy at long term follow-up supports the ability of TPLO to protect the CrCL. Following TPLO, cranial tibial thrust is eliminated during
weight bearing, thus reducing the work that the CrCL has to perform. TPLO can be performed as initially
described by Slocum, but a minimally-invasive technique is now available which reduces patient morbidity
and is much less invasive. Minimally-invasive TPLO requires arthroscopic-assistance and a small medial incision over the proximal aspect of the tibia. Following surgery, patients are recommended to start a controlled, progressive rehabilitation program that focuses on increasing muscle strength and joint motion. Outcome following TPLO in dogs having a stable partial tear has been excellent. Most patients are expected to
return to near-normal function. Patients are permitted to return to running after adequate healing of the osteotomy, typically at 8 weeks following surgery. Rehabilitation continues for another 8 weeks at which time
most patients are close to reaching their level of maximum performance. Patients treated in this manner are
expected to have no restrictions and to perform well in athletic or working roles.
Extracapsular prosthetic ligament repair techniques can also have an acceptable outcome in dogs with partial CrCL tears. This technique can be performed in a minimally-invasive manner or by a traditional arthro14
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tomy. The prosthetic ligament will provide immediate static stability to the stifle and will allow fibrous tissue to form over time to provide a biologic tissue to provide long term support. It is unknown whether placement of an extracapsular lateral prosthetic ligament will prevent continued deterioration of a partial CrCL
tear to a complete tear. A potential problem with this technique is the continued presence of cranial tibial
thrust in the patient and the potential for cyclic failure of the prosthetic ligament. Materials used for extracapsular prosthetic CrCL repair have been found to stretch or break in the early postoperative period, leading to recurrent stifle instability. Recent studies support the placement of lateral extracapsular prosthetic ligaments in an isometric position (known as the F2-T3 sites). Isometric positioning reduces strain on the prosthetic ligament during normal range of motion of the stifle and is thought to decrease the risk of implant failure. In addition, isometric positioning of the ligament allows more normal range of motion and proper rotation of the stifle during flexion. Suture anchors and bone tunnels are typically used to anchor the prosthetic ligament at the isometric positions. The material chosen for the ligament prosthesis should be strong
and resistant to elongation. A braided polyblend polyethylene material known as FiberWire and FiberTape
(Arthrex Vet Systems, Naples, FL) meets these criteria and is successfully used routinely for extracapsular
prosthetic CrCL repair in dogs. Following surgery, patients are recommended to start a controlled, progressive rehabilitation program that focuses on increasing muscle strength and joint motion. Patients are permitted to return to running at 16 weeks in most dogs. Rehabilitation continues for another 8 weeks at which
time most patients are close to reaching their level of maximum performance. Patients treated in this manner are expected to have no restrictions and to perform well in athletic or working roles. Osteoarthritis may
be slightly more severe in this group of patients compared to TPLO patients.
Arthroscopy is an invaluable tool for evaluation of the stifle in dog’s having a presumptive tear of the CrCL. Many early partial tears of the ligament are not visible to the naked eye and can only be identified with
magnification. It would be easy to miss this diagnosis and leave the patient untreated, leaving the patient
with an increased risk of developing osteoarthritis and meniscal damage. Arthroscopic assisted surgery im-
The torn fibers of the CrCL can be debrided carefully with a shaver or radiofrequency probe. Complete debridement of fibers is not needed.
Debridement of fibers should be performed if easily accessible or if needed to view the menisci.
Debridement of torn fibers at the origin of the CrCL (a) was performed prior to TPLO. The remaining fibers (b) appear to have good integrity and no obvious cranial drawer could be palpated. This would be considered a “stable” partial CrCL tear.
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B.S. Beale
proves accuracy of treatment of torn CrCL fibers and meniscal tears. Iatrogenic cartilage damage during
meniscectomy is reduced. Arthroscopy can be performed using traditional portals or it can be performed
through a standard or mini-arthrotomy. Use of an arthroscope through an arthrotomy incision dramatically decreases the difficulty of the procedure. The use of the scope allows the surgeon to make a much smaller arthrotomy, reducing patient morbidity while at the same time improving visualization of joint structures.
The arthrotomy incision acts as the egress, scope and the instrument portals. Extravasation of subcutaneous
tissues with arthroscopic fluids is avoided. The learning curve for arthroscopy is dramatically reduced. The
need for many instruments and equipment typically used for arthroscopy is eliminated.
Surgical debridement of the torn CrCL is a factor to be considered. Surgical debridement of fibers is generally performed in complete tears of the CrCL, primarily to improve visualization of the menisci. The removal of torn fibers to prevent osteoarthritis or pain is unfounded. It is known that intact fibers of the CrCL may be at various stages of degeneration at the time of partial CrCL tear. Some surgeons believe the entire CrCL ligament should be removed if a partial tear has occurred due to the possibility of fiber degeneration and the compromised ligament acting as a potential source of postoperative pain. Other surgeons have
achieved a good outcome with preservation of the intact functional fibers and believe that the added stability of the remaining ligament is beneficial for the patient. At the present time, it is recommended that torn
fibers and non-functional stretched fibers of the CrCL be debrided. It is critical that debridement of the torn
fibers be performed meticulously to avoid iatrogenic damage to articular cartilage, the remaining fibers of
the CrCL, the fibers of the caudal cruciate ligament and the cranial ligaments if the medial and lateral menisci. Intact, functional fibers are recommended in patients treated by TPLO to be preserved in hopes of providing adjunctive stability and reducing the chance of future osteoarthritis and meniscal tears. Complete ligament debridement may be best in patients treated with an extracapsular technique due to anticipated
stretching of the prothetic ligament and retrun of cranial tibial translation. This amount of instability will
likely lead to additional tearing of the CrCL and increase the chance of pain and lameness.
Debridement of the entire CrCL (a) was performed prior to TPLO in this patient due to laxity present in the remaining fibers. This patient
had approximately 7 mm of cranial drawer with the stifle in flexion and 4 mm in extension.
This dog had a “stable”partial tear of the CrCL and was treated by arthroscopic debridement of the torn fibers (a) and TPLO. Note the synovitis at the insertion of the CrCL (b). The ligament appears to have good integrity (c) and the inflammation has subsided at the time of plate
removal 14 months later.
16
Brian S. Beale
Come riuscire a riparare
con successo le lussazioni mediali
della rotula in cani di piccola
taglia e nei gatti
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How to succeed in repairing medial patellar luxation
in small dogs and cats
Texas (USA)
Patella luxation is a problem in all breeds and sizes of dogs, but the condition is most common in small breed
dogs. Commonly affected breeds include the Yorkshire terrier, maltese, toy poodle, miniature poodle,
pomeranian, pekingese and chihuahua. Medial patellar luxation predominates in both small and large breeds,
although past literature suggests lateral luxation is much more common in large breeds. Patellar luxation occurs less frequently in cats and medial luxation is most common. Patellar luxation is generally graded from
1-4 based on increasing severity. Grade 1 patellar luxations are generally not repaired, but surgical repair is
recommended for grades 2-4, depending on the age and clinical presentation of the patient. Treatment of medial patella luxation may be conservative (small breeds only) or surgical. The decision as to which method is
applicable for a patient is dependent upon the clinical history, physical findings and the age of the patient. An
older patient in which patella luxation is noted as an incidental finding on physical examination and in which
the client reports nonclinical lameness does not warrant surgical intervention. Rather, the client should be informed as to the clinical signs associated with patella luxation. Surgery is advised in the young adult patient
even though no clinical problem is apparent since intermittent luxation may prematurely wear the articular
cartilage of the patella. Surgery is indicated in any aged patient exhibiting lameness and is strongly advised
in a patient with active growth plates since skeletal deformity may worsen rapidly. However surgical techniques used in actively growing animals should be those that will not adversely affect skeletal growth. Surgical options include trochleoplasty, trochlear wedge recession, trochlear block recession, tibial tuberosity transposition, tibial tuberosity transposition, rectus femoris transposition, retinacular imbrication, derotational suture, retinacular releasing incision and corrective osteotomy in cases of femoral or tibial deformity. In severe
cases that do not respond to the above treatments, patellectomy and stifle arthrodesis are a possibility; these
techniques are fortunately rarely needed (these techniques will not be presented).
CLINICAL FINDINGS
Pet owners typically report a skipping lameness in affected pets. Typically the pet uses the affected leg normally between skipping episodes. Some owners do not recognize any lameness or gait abnormality in affected patients. Patellar luxation frequently occurs bilaterally, but may one stifle may be more severely affected than the other. Owners often report a slow progression in severity of clinical lameness. The lameness
may appear to resolve in some patients over time, but this may be due to the progression of patellar luxation from grade 2 to grade 3. The skipping gait may disappear because the patella is no longer displacing
into and out of the trochlear groove. It the patella remains in a luxated position, the patient may not exhibit obvious lameness, but may have a bowlegged gait. Lameness that acutely worsens in patients with patellar luxation may be associated with a concomitant tear of the cranial cruciate ligament. Cranial cruciate ligament injury occurs in approximately 25% of patients with patellar luxation.
Patellar luxation is generally graded from 1-4 based on increasing severity. Grade 1 luxation is not associated with clinical lameness. The patella can be displaced out of the trochlear groove by applying digital pressure, but spontaneous luxation does not occur. Grade 2 luxation typically presents with an intermittent nonweightbearing lameness, the typical “skipping-gait”. Digital displacement of the patella is possible during examination, but the patella moves back into the trochlear groove when pressure is released or when the stifle
is extended. Grade 3 luxation may present with intermittent non-weightbearing lameness or persistent
weightbearing lameness. Many of these patients do not have an obvious lameness, but rather display a bowlegged posture when walking. The patella is typically luxated at the time of examination, but can be replaced
into the trochlear groove with digital pressure. The patella usually quickly luxates again once pressure is released or the stifle is moved through a range of motion. Grade 4 luxation presents as a persistent weightbearing lameness or bowlegged gait. The patella is fixed in a luxated position and can not be reduced with
digital pressure, even in the anesthetized patient.
RADIOGRAPHIC FINDINGS
Patients having medial patellar luxation should be evaluated with appropriately positioned orthogonal survey radiographic views of the stifle. Orthogonal views of the entire femur and tibia should also be evaluated if limb deformity is present in small breed dogs and in all medium and large breed dogs with patellar lux18
ation. The patient should be assessed for patella position, distension of the
joint capsule, presence of tibial translation, tibial tuberosity position, axial
alignment of the femur and tibia, torsional alignment of the femur and tibia, and osteoarthritis. CT imaging is recommended, if available; to more accurately assess hind limb alignment.
Radiographic changes vary from no obvious change to severe limb deformity and marked patellar displacement depending on the grade of luxation,
age at onset of patellar luxation and duration of the condition. Minimal radiographic changes are seen in adult patients with uncomplicated grade 1 or
2 medial patellar luxation. Some patients have no abnormal radiographic
changes. Radiographic changes that may be seen include patellar displacement, tibial tuberosity displacement, and rarely mild osteoarthritis and mild
joint effusion. Grade 3 and grade 4 patellar luxations are more likely to have
radiographic patellar displacement, tibial tuberosity displacement, joint effusion and osteoarthritis. These patients are also more commonly affected
with axial or torsional abnormalities of the femur or tibia. Patients with severe medial patellar luxation and abnormal limb alignment usually have distal femoral varus, proximal tibial valgus, internal femoral torsion or internal
tibial torsion. Radiographic assessment of the depth of the trochlear groove
is usually best evaluated by palpation or gross observation, but severely
shallow trochlear grooves can be seen radiographically.
Radiographic changes are most severe in puppies where the onset of patellar luxation occurs at an early age when the physis is undergoing rapid
growth. Medial luxation of the patella in these dogs causes compression on
one side of the distal femoral and proximal tibial physes and compression on
the opposite side. As a consequence, the medial aspect of the femoral physis
has retarded growth and the lateral aspect has accelerated growth resulting
in distal femoral varus. The lateral aspect of the tibial physis has retarded
growth and the medial aspect has accelerated growth resulting in proximal
tibial valgus. Torsional deformity of the femur and tibia can also occur simultaneously. Correction of the deformity is usually based on comparison
of the degree of angulation and torsion found on radiographic examination
of the affected patient in comparison to normal reference values. The surgeon should be cautious when interpreting the measured angle of axial deformity as torsional deformity can artificially raise or lower the actual
amount of axial malalignment. A CT scan is likely to give the most accurate
measurement of axial and torsional deformity.
Patients with medial patellar luxation should also be evaluated for the potential for concomitant cranial cruciate injury. Typical radiographic changes
include joint distension and cranial tibial displacement. Osteoarthritic
changes are more likely with cranial cruciate ligament injury. If cranial cruciate ligament injury is suspected, measurement of the slope of the tibial
plateau may be helpful when deciding on a surgical plan.
Complications associated with medial patellar luxation (MPL) repair can be
categorized as intraoperative or postoperative. Complications are fairly common, but fortunately many are easy to resolve or prevent. Most complications can be avoided by better preoperative planning, meticulous surgical
technique and appropriate postoperative care.
B.S. Beale
This grade 4 MPL patient has varus
deformity of the distal femur and valgus deformity of the proximal tibia.
Slight internal rotation of the bones is
also present.
Tears of the cranial cruciate ligament
is seen in approximately 25% of dogs
with MPL.
DECISION-MAKING FOR PATELLAR LUXATION REPAIR
Many surgical options are available when considering repair of the luxating patella. It is important to consider the underlying problems associated with the particular luxation when choosing a surgical plan. Factors
to consider include, depth of the trochlear groove, alignment of the quadriceps mechanism (quadriceps,
patella, patellar tendon), and the presence of excessive laxity or tension of the joint capsule and retinacular
tissues medially and laterally. The surgical options chosen should alleviate the underlying factor contributing to the luxation. For example, if a dog has good alignment of the quadriceps mechanism, but a shallow
trochlear groove- the surgical plan should include a technique to deepen the femoral trochlea, but not a tibial tuberosity transposition.
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METHODS TO DEEPEN THE TROCHLEA
Three methods are commonly used to deepen a shallow
trochlear groove. These methods are described below. A headto-head comparison as not been performed to document superior efficacy of one technique compared to the others. Usually
trochleoplasty is reserved for toy-breed dogs and cats.
Trochlear wedge recession and trochlear block recession are
preferred for small, medium and large breed dogs, but also can
be performed effectively in toy-breed dos and cats with a slight
increase in technical difficulty.
Trochleoplasty - Trochleoplasty is a traditional technique that
involves removal of articular cartilage and subchondral bone
from the trochlear sulcus, thereby deepening the sulcus. Fibrocartilage repair is generally seen. This technique is considered less desirable to cartilage-sparing techniques described
below, although it is sometimes used in toy breeds very successfully. Trochleoplasty is technically easy to perform. A
deepened groove can be quickly formed using appropriate
sized rongeurs. Attention should be paid to ensuring adequate
depth of the groove proximally.
Trochlear Wedge Recession - Trochlear wedge recession provides a means of adequately deepening the trochlear sulcus,
while preserving most of the articular cartilage. This technique is described elsewhere, but basically involves removal of
a v-shaped wedge of bone and cartilage from the trochlear sulcus, removal of underlying bone, followed by replacement of
the original wedge in a recessed position. This is an excellent
technique, but technically more demanding than trochleoplasty. The technique is performed using a fine-tooth hand sawblade. Care should be taken when beginning the saw cut, not
to excoriate the adjacent cartilage due to slippage. The cut is
initiated perpendicular to the cartilage surface adjacent to the
peak of the trochlear ridge. Once the saw blade has engaged
the subchondral bone, the blade is gradually redirected in the
proper direction, parallel to the v-shaped trochlear groove. A
cut is made from the lateral and medial ridge, meeting deep to
the central sulcus of the groove. The wedge is removed and
carefully stored to avoid accidental discard. The groove is further deepened by removing a block of bone from one side of
the groove by making a parallel cut with the handsaw. A modification of this technique is to broaden and deepen the proximal aspect of the new, deepened groove by performing a partial trochleoplasty in the proximal aspect of the groove only, as
described above using rongeurs. A portion of bone can also be
removed from the underside of the trochlear wedge to further
deepen the groove. The wedge is replaced and the adequate
depth of the groove is documented. Fixation of the wedge is
usually not needed due to pressure applied from the patella lying above and the congruency between the groove and wedge
geometry.
Trochlear Block Recession - Trochlear block recession is similar to trochlear wedge recession except that a block-shaped
wedge is removed from the trochlear sulcus rather than a vshaped wedge. This technique allows a deeper sulcus proximally, which may provide better biomechanical stability of the
20
A shallow trochlear groove should be deepened using a
trochlear wedge or trochlear block recession.
Saw-blade cut for trochlear block recession.
Osteotome cut begins above the intercondylar notch.
Osteotome is used to elevate the trochlear block.
B.S. Beale
patella when the stifle is in an extended position. This is an excellent technique, but technically more demanding than
trochleoplasty. The technique is performed using a fine-tooth
hand saw-blade, a small osteotome and mallet. Care should be
taken when beginning the saw cut, not to excoriate the adjacent cartilage due to slippage. The cut is initiated perpendicular to the cartilage surface adjacent to the peak of the trochlear
ridge. Once the saw blade has engaged the subchondral bone,
the blade is gradually redirected in the proper direction, perpendicular to the long axis of the bone. A cut is made from the
lateral and medial ridge and each cut is carried to an adequate
depth deep to the central sulcus of the groove. The block of
cartilage and bone is removed gently using an osteotome and Bone is removed below the block deepening the groove
mallet. The osteotome is positioned just proximal to the inter- after replacing the block
condylar notch beginning at the depth of the trochlear cuts.
The osteotome is directed towards the proximal extent to the
trochlear groove. Gentle raps with the mallet will advance the osteotome, dislodging the trochlear block.
The trochlear block is removed and carefully stored to avoid accidental discard. The groove is further deepened by removing a complimentary block of bone from the deep portion of the groove by making a parallel cut with the osteotome or by deepening with a rongeur. A portion of bone can also be removed from the
underside of the trochlear block to further deepen the groove. The block is replaced and the adequate depth
of the groove is documented. Fixation of the block is not needed due to pressure applied from the patella lying above and the congruency between the groove and block geometry.
ALIGNMENT OF THE QUADRICEPS MECHANISM
Tibial Tuberosity Transposition - Tibial tuberosity transposition is an excellent method of improving alignment of the
patellar mechanism in patients having an abaxially displaced
tibial tuberosity. If the tuberosity is displaced medially, luxation occurs medially; therefore, the tuberosity must be transposed laterally and secured. Lateral luxations require medial
tibial tuberosity transposition. An osteotomy is performed as
previously described; the tuberosity is transposed then secured with a single or multiple k-wires. An attempt is made
when performing the osteotomy to leave the distal cortical
bone intact to act as a tension band against the pull of the
quadriceps mechanism. If the tuberosity is freed completely, it
is prudent to secure the transposed bone with either a pin and
tension band or a lag screw. The tuberosity should be transposed to a position that restores axial alignment to the quadriceps mechanism.
The tibial tuberosity is moved laterally an appropriate dis-
Rectus Femoris Transposition - This is a technique described tance to align the patellar mechanism such that the patelby Dr. Barclay Slocum for use in bow-legged dogs having me- la lies in the trochlear groove during flexion and extension.
dial patellar luxation. This technique is done in combination
with a medial releasing incision. A trochlear deepening technique should also be performed as needed. The rectus femoris is transected from its pelvic origin with a
small piece of attached bone, then laterally transposed by tunneling under the vastus lateralis and reattaching it to the cervical tubercle or third trochanter of the proximal femur with wire or heavy suture. This realigns the quadriceps mechanism, restoring a straight-line pull.
Corrective Osteotomy of the Femur - Varus deformity of the distal femur is a contributing factor to medial patellar luxation particularly in large breed dogs. Accurate radiographic assessment of the distal femur
is needed to measure angulation. If the distal femur has a varus deviation of greater than 10° a varus corrective osteotomy may be needed. A closing wedge osteotomy using a bone plate is commonly used for this
procedure.
Corrective Osteotomy of the Tibia - Valgus deformity of the proximal tibia may require corrective osteotomy using a closing wedge osteotomy. This typically is only needed in dogs having severe medial patel21
B.S. Beale
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lar luxation when they were puppies. Unequal pressure on the growth plate leads to incongruent growth
and angulation of the proximal tibia.
RETINACULAR IMBRICATION
Lateral imbrication is usually performed with correction of a medial patellar luxation as a means of creating
lateral restraint. The stretching of the lateral joint capsule and retinaculum occurs chronically with longstanding patellar luxation. Occasionally a traumatic luxation may result in rupture of these tissues; imbrication is also a good technique for repair in this case. Imbrication is usually performed using heavy, absorbable, monofilament suture placed in a vest-over-pants- or horizontal mattress pattern. Care must be taken not to tighten the retinaculum excessively (especially if a retinacular releasing incision has been performed on the opposite side), because it is possible to create an iatrogenic luxation in the opposite direction.
An alternative method of supplying lateral restraint is placement of a lateral derotational suture from the lateral fabella to a bone tunnel in the tibial tuberosity.
RETINACULAR RELEASING INCISION
A medial releasing incision is performed if fibrous hyperplasia has occurred medially following prolonged
or severe medial patellar luxation. An incision is made through the retinacular tissues in a medial parapatellar location. The incision should extend proximally beside the medial edge of the quadriceps tendon.
Placement of the incision in this location will release the insertion of the sartorius muscle, decreasing pull on
the patella. The incision occasionally has to be carried deeper to include the joint capsule if marked joint
capsular fibrosis has occurred creating excessive medial restraint. The incision is left open and not sutured.
Arthroscopic medial releasing incisions can be performed. This technique is quick, easy to perform and has
low morbidity. Long-term follow-up is presently unavailable. In addition, the clinical indications with this
technique are presently unknown.
22
Brian S. Beale
Artrotomia a guida artroscopica…
cavalca l’onda del futuro
Sabato, 18 Settembre, ore 14.00
23
B.S. Beale
Arthroscopic-assisted arthrotomy… ride the wave
of the future
Texas (USA)
Arthroscopy has revolutionized the treatment of joint disease in man and animals. Arthroscopic-assisted surgical techniques reduce postoperative pain, the length of hospital stay and shorten the time required for return to function. At the present time, arthroscopy in animals is used primarily by veterinary surgeons having advanced training, usually working out of specialty practices or in a university hospital. General practitioners who routinely perform joint surgery have been slow to adopt arthroscopy due to the learning curve
involved. Consideration should be given to implementing arthroscopy at the time of arthrotomy to enhance
surgical view, improve surgical treatment and assist in arthroscopic training. The arthroscopic procedure is
simplified when using arthroscopy at the time of arthrotomy. Arthroscopic exploration can be attempted prior to or during routine arthrotomy as previously described.1 May conditions affecting the joints are best
viewed arthroscopically including, OCD of the shoulder and elbow, ligamentous and tendinous injuries of
the shoulder, fragmented medial coronoid process, cranial cruciate ligament tears and meniscal tears.
BENEFITS OF ARTHROSCOPY AT THE TIME OF ARTHROTOMY
Arthroscopy is easier to perform when used at the time of arthrotomy. The arthrotomy incisions functions
as the arthroscope, instrument and egress portal. Extravasation of fluids into the subcutaneous tissues is unlikely due to the ease of fluid egress from the arthrotomy incision. The arthroscope can be quickly and easily moved in and out of the joint as needed. The surgeon’s orientation of the scope and anatomic target is
improved. The scope can be positioned in the desired location by gross observation, while the anatomic
structure of interest can be assessed more completely using the magnification and enhanced viewing field
provided by the arthroscope. Over time, the surgeon will improve their arthroscopic skills to the point where
arthrotomy may no longer be needed. Other important advantages of arthroscopy compared to arthrotomy
include decreased pain, earlier return to function, improved visualization and more precise and accurate
treatment. Other potential advantages include reduced scarring of the skin, decreased periarticular fibrosis
and improved long term function. Smaller arthrotomy incisions can be made when arthroscopy is used at
the same time, thus capturing some of the benefits gained form the use of arthroscopy.
Postoperative Pain
Pain following surgery of the stifle can be substantial. Disruption of tissues leads to pain. Pain is generated
locally by cellular mechanisms and activation of pain receptors. The perception of pain is dependent on
transmission of impulses through the peripheral and central neural pathways. The source of pain may include skin, subcutaneous tissues, muscle, ligaments, tendons, synovial membrane, and subchondral bone.
Inflammatory mediators within the synovial fluid also cause pain. Surgical pain can be decreased by appropriate preemptive analgesia, adjunctive NSAID therapy, reducing the number and extent of tissues invaded,
and by meticulous handling of tissues. Arthroscopic-assisted surgery is minimally-invasive, sparing soft tissues around the joint, thereby reducing painful stimuli.
Return to Function
Early return to function is desirable to reduce muscle atrophy and preserve joint motion following surgery.
Limb disuse quickly leads to muscle atrophy. The loss of muscle mass results in increased force on the joint,
which may predispose to osteoarthritis and additional injury to ligamentous structures. Pain, tissue swelling,
activity restriction and bandaging contribute to postoperative loss of joint range of motion. Early range of
motion exercise is advantageous due to the tendency for joints to become stiff following surgery. Arthroscopic-assisted techniques also help to preserve joint range of motion due to its effect on decreasing postoperative pain and swelling.
Visualization of Joint Structures
Arthroscopic evaluation is superior to open surgical evaluation for 3 reasons:
1. magnification of joint structures
2. greater access to joint structures
3. assessment of joint structures in a fluid medium
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ORTOPEDIA
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The biceps tendon cannot be seen through a caudolateral arthrotomy, but is easily seen if the arthroscope is employed.
Tears (b) of the biceps tendon (a) are easily viewed during
arthroscopy of the shoulder.
Osteochondral fragments (b) near the biceps tendon (a) can be seen
with the arthroscope, but not with a routine arthrotomy.
Fragments of the medial coronoid process are best seen arthroscopically.
Multiple fragments of the medial coronoid process can be easily
missed with arthrotomy.
Partial tears of the cranial cruciate ligament not visible to the
naked eye can be seen easily with the arthroscope.
25
B.S. Beale
Visualization of the menisci can be difficult using an arthrotomy.
Arthroscopic assessment of the menisci improves visualization of
small meniscal tears due to magnification. This tear would likely
not be visible to the naked eye.
A bucket-handle tear is more precisely removed arthroscopically
using a grasper and a cutting forcep.
Large bucket-handle tears can be removed through small stab incisions as the surgeon becomes more proficient with arthroscopy, resulting in decreased morbidity.
Meniscal tears can be difficult to see during routine arthrotomy.
A probe is used to assess the meniscus during arthroscopy, helping
the surgeon to identify tears that can not be seen with the naked
eye during arthrotomy.
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Magnification of intraarticular structures allows for more accurate identification of pathological change. Early osteoarthritic changes to articular cartilage, not visible to the naked eye, are clearly seen arthroscopically.
Fine and course fibrillation, superficial erosions and neovascularization of the cartilage are readily evaluated
and documented. Small radial and axial tears of the menisci often become evident only after magnification.
SHOULDER
Arthroscopic assessment of the shoulder is greatly enhanced during arthrotomy due to the ability to evaluate the entire joint through a typical caudolateral approach. The medial, lateral and cranial compartments
can not be evaluated with a caudolateral arthrotomy, therefore osteochondral fragments or tears of the ligamentous or tendinous structures in these regions may be missed. OCD of the shoulder is the most common indication for arthrotomy or arthroscopy of the shoulder. This condition often leads to fragmentation
of the cartilage flap. Loose fragments frequently float into the medial or cranial aspect of the joint. Fragments
may move into the bicipital tendon sheath causing inflammation and irritation. Arthroscopy gives the surgeon the ability to identify and remove these potentially painful fragments that might otherwise be left behind when performing a routine arthrotomy.
ELBOW
Arthroscopic evaluation of the elbow at the time of arthrotomy is particularly useful to better evaluate the
patient with elbow dysplasia. Fragmentation of the medial coronoid process can be assessed arthroscopically or by arthrotomy. When assessed using an arthrotomy, most surgeons use a minimally-invasive approach
in order to preserve the medial collateral ligament of the elbow. The field of view is quite small when evaluating the joint by this manner. Attempts at improving the view by applying a valgus force to the elbow may
result in iatrogenic tearing of the ligament. In addition, the medial coronoid process is often times has multiple fragments. Arthrotomy may allow removal of the main fragment, but smaller fragments and those located cranial to the medial collateral ligament may be missed. Arthroscopy gives better views of the region
and allows more complete removal of the fragments. The subchondral bed can also be more accurately treated with curettage or abrasion arthroplasty when viewed with the arthroscope. Lastly, The extent of cartilage
damage of the medial humeral condyle, medial coronoid process and trochlear notch can be assessed accurately arthroscopically, which assists the surgeon’s ability to develop a long term plan for management of
the condition and to give the pet’s owner a more accurate prognosis.
STIFLE
Arthroscopic evaluation of the stifle allows more thorough evaluation of the cranial cruciate ligament and
menisci. The cranial cruciate ligament can be assessed for partial or complete tears. Complete tears of the
ligament are easy to see by arthrotomy or arthroscopy. Partial tears, on the other hand, are often not visible
by the naked eye. Arthroscopic examination of the cranial cruciate ligament gives the surgeon the ability to
identify and document partial tears of the ligament prior to the progression of osteoarthritis (OA) and complete tearing of the ligament. Surgical intervention in the early stages of cruciate disease may help reduce the
severity of future OA and preserve the integrity of the remaining fibers of the ligament. Meniscal views are
also improved due to the ability to position the scope directly adjacent to meniscus in both the cranial and
caudal joint compartment. Partial meniscectomy can be performed more accurately when assessed arthroscopically. Meniscectomy performed with the naked eye often leads to iatrogenic cartilage damage or inadequate removal of damaged meniscal tissue. Arthroscopic-assisted meniscectomy through an arthrotomy incision gives a magnified view of the meniscus, which helps prevent inadvertent damage to the cartilage during instrumentation and allows the surgeon to assess the meniscus repeatedly to ensure complete removal
of damaged portions of the meniscus.
REFERENCES
1.
Small Animal Arthroscopy. In: Beale BS, Hulse DA, Schulz KS, Whitney WO. Small Animal Arthroscopy. Philadelphia, WB Saunders, 2003.
27
Brian S. Beale
Lussazione mediale della rotula
in cani di grossa taglia…
qual è la differenza?
28
B.S. Beale
Medial patellar luxation in large dogs…
what is the difference?
Texas (USA)
Patella luxation occurs most frequently in small breed dogs, but the prevalence is increasing in large breed
dogs. In the past, large breed dogs were described as being predominately affected by lateral patellar luxation. Lateral luxation certainly occurs more commonly in large breed dogs compared to small breed dogs,
but medial luxation is most in large breed dogs as well. Medial patellar luxation in large breed dogs can
share many characteristics with small breed dogs. Large breed dogs tend to be overrepresented with distal
femoral varus deformity as a cause for medial patellar luxation. This lecture will focus on evaluation and
treatment of distal femoral femoral varus and proximal tibial valgus deformities in MPL patients.
FUNCTIONAL ANATOMY
Quadriceps mechanism
The patella is essentially a sesamoid bone within the quadriceps mechanism. The quadriceps mechanism
is composed of the quadriceps muscle, the patella and the patellar tendon. The quadriceps muscle has 4
muscle bellies. The rectus femoris muscle originates from the ventral aspect of the ilium just cranial to the
acetabulum. The vastus lateralis, intermedius and medialis originate from the proximal femur. All of these
muscle bellies form a common tendon containing the patella that inserts on the tibial tuberosity. The patella glides in the trochlear groove of the distal femoral condyle. The quadriceps mechanism functions similar to a simple pulley. Contraction and relaxation of the muscle leads to flexion and extension of the stifle joint. Proper function requires adequate alignment of the quadriceps mechanism, the femur and tibia.
The rectus femoris plays an important role in the tendency for the patella to remain in the trochlear groove.
The patella will tend to remain within the trochlear groove if a line drawn from the origin of the rectus
femoris to its insertion on the tibial tuberosity passes through the trochlear groove. The peri-articular soft
tissues such as the joint capsule and femoro-patellar ligaments add secondary support to the femoro-patellar
articulation.
Femur and tibia
It is imperative that the femur and tibia have adequate alignment in the frontal and sagittal planes for proper patella stability. Alignment of the frontal plane is most important when considering patellar luxation. Excessive varus or valgus deviation of the diaphysis of either bone may influence patellar position. Excessive
internal or external torsion of either bone can also influence patellar position. In addition, the angle of inclination and anteversion of the femoral head can also play a role in the dynamics of the quadriceps mechanism. Common anatomic abnormalites that may contribute to medial patellar luxation include coxa vara,
genu varum, distal femoral varus, external torsion of the distal femur, a shallow trochlear sulcus, proximal
tibial varus or valgus, internal tibial torsion, and medial displacement of the tibial tubercle.
RADIOGRAPHIC FINDINGS
Patients having medial patellar luxation should be evaluated with appropriately positioned orthogonal survey
radiographic views of the stifle. Orthogonal views of the entire femur and tibia should also be evaluated if
limb deformity is present in small breed dogs and in all medium and large breed dogs with patellar luxation. The patient should be assessed for patella position, distension of the joint capsule, presence of tibial
translation, tibial tuberosity position, axial alignment of the femur and tibia, torsional alignment of the femur and tibia, and osteoarthritis. CT imaging is recommended, if available; to more accurately assess hind
limb alignment.
Radiographic changes vary from no obvious change to severe limb deformity and marked patellar displacement depending on the grade of luxation, age at onset of patellar luxation and duration of the condition. Minimal radiographic changes are seen in adult patients with uncomplicated grade 1 or 2 medial patellar luxation. Some patients have no abnormal radiographic changes. Radiographic changes that may be seen
include patellar displacement, tibial tuberosity displacement, and rarely mild osteoarthritis and mild joint effusion. Grade 3 and grade 4 patellar luxations are more likely to have radiographic patellar displacement,
tibial tuberosity displacement, joint effusion and osteoarthritis. These patients are also more commonly affected with axial or torsional abnormalities of the femur or tibia. Patients with severe medial patellar luxa29
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tion and abnormal limb alignment usually have distal femoral varus, proximal tibial valgus, internal femoral torsion or internal tibial torsion. Radiographic assessment of the depth of the trochlear groove is usually best evaluated by palpation or gross observation, but severely shallow trochlear
grooves can be seen radiographically.
Radiographic changes are most severe in puppies where the onset of patellar luxation occurs at an early age when the physis is undergoing rapid
growth. Medial luxation of the patella in these dogs causes compression on
one side of the distal femoral and proximal tibial physes and compression on
the opposite side. As a consequence, the medial aspect of the femoral physis
has retarded growth and the lateral aspect has accelerated growth resulting
in distal femoral varus. The lateral aspect of the tibial physis has retarded growth and the medial aspect has accelerated growth resulting in proximal tibial valgus. Torsional deformity of the femur and tibia can also occur simultaneously.
Correction of the deformity is usually based on comparison of the degree of
angulation and torsion found on radiographic examination of the affected patient in comparison to normal reference values. The surgeon should be
cautious when interpreting the measured angle of axial deformity as torsional deformity can artificially raise or lower the actual amount of axial
malalignment. A CT scan is likely to give the most accurate measurement
of axial and torsional deformity.
Patients with medial patellar luxation should also be evaluated for the potential for concomitant cranial cruciate injury. Typical radiographic changes
include joint distension and cranial tibial displacement. Osteoarthritic
changes are more likely with cranial cruciate ligament injury. If cranial cruciate ligament injury is suspected, measurement of the slope of the tibial
plateau may be helpful when deciding on a surgical plan.
Complications associated with medial patellar luxation (MPL) repair can be
categorized as intraoperative or postoperative. Complications are fairly common, but fortunately many are easy to resolve or prevent. Most complications can be avoided by better preoperative planning, meticulous surgical
technique and appropriate postoperative care.
This grade 4 MPL patient has varus
deformity of the distal femur and valgus deformity of the proximal tibia.
Slight internal rotation of the bones is
also present.
DECISION-MAKING FOR PATELLAR LUXATION REPAIR
Many surgical options are available when considering repair of the luxating
patella. It is important to consider the underlying problems associated with
the particular luxation when choosing a surgical plan. Factors to consider include, depth of the trochlear groove, alignment of the quadriceps mechanism
(quadriceps, patella, patellar tendon), and the presence of excessive laxity or
tension of the joint capsule and retinacular tissues medially and laterally.
The surgical options chosen should alleviate the underlying factor contributing to the luxation. For example, if a dog has good alignment of the
quadriceps mechanism, but a shallow trochlear groove- the surgical plan
should include a technique to deepen the femoral trochlea, but not a tibial
tuberosity transposition.
Tears of the cranial cruciate ligament
is seen in 25% of dogs with MPL.
ALIGNMENT OF THE QUADRICEPS MECHANISM
Tibial Tuberosity Transposition - Tibial tuberosity transposition is an ex- Partial tears are particular common in
cellent method of improving alignment of the patellar mechanism in patients large breed dogs with long standing
having an abaxially displaced tibial tuberosity. If the tuberosity is displaced MPL.
medially, luxation occurs medially; therefore, the tuberosity must be transposed laterally and secured. Lateral luxations require medial tibial tuberosity transposition. An osteotomy
is performed as previously described; the tuberosity is transposed then secured with a single or multiple kwires. An attempt is made when performing the osteotomy to leave the distal cortical bone intact to act as
a tension band against the pull of the quadriceps mechanism. If the tuberosity is freed completely, it is prudent to secure the transposed bone with either a pin and tension band or a lag screw. The tuberosity should
be transposed to a position that restores axial alignment to the quadriceps mechanism.
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Rectus Femoris Transposition - This is a technique described by Dr. Barclay Slocum for use in bow-legged
dogs having medial patellar luxation. This technique is done in combination with a medial releasing incision. A trochlear deepening technique should also be performed as needed. The rectus femoris is transected from its pelvic origin with a small piece of attached bone, then laterally transposed by tunneling under the vastus lateralis and reattaching it to the cervical tubercle or third trochanter of the proximal femur
with wire or heavy suture. This realigns the quadriceps mechanism, restoring a straight-line pull.
Corrective Osteotomy of the Femur - Varus deformity of the distal femur is a contributing factor to medial patellar luxation particularly in large breed dogs. Accurate radiographic assessment of the distal femur
is needed to measure angulation. If the distal femur has a varus deviation of greater than 10° a varus corrective osteotomy may be needed. A lateral closing wedge or medial opening wedge osteotomy using a bone
plate is commonly used for this procedure.
Corrective Osteotomy of the Tibia - Valgus deformity of the proximal tibia may require corrective osteotomy using a medial closing wedge or lateral opening wedge osteotomy. This typically is only needed in
dogs having severe medial patellar luxation when they were puppies. Unequal pressure on the growth plate
leads to incongruent growth and angulation of the proximal tibia.
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Infezioni ortopediche…
cosa c’è di nuovo?
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B.S. Beale
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2010, Bologna
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CANINA
Orthopedic infections… What is new?
Texas (USA)
Orthopedic infections have always been a risk following surgery, but recent trends would suggest higher
risks and morbidity in dogs afflicted with infection following orthopedic surgery. Many factors contribute to
the prevalence of infection in orthopedic patients. These factors can be categorized as patient factors, surgical factors, bacterial factors and environmental factors. This lecture discusses current thoughts on the influence of each of these factors on orthopedic infections that are bacterial in nature. The prevention and treatment of orthopedic infections will be emphasized.
PATIENT FACTORS
Some patients may be at greater risk of developing orthopedic infections. Dogs having the following are
more likely to develop infections postoperatively:
1. Recurrent pyoderma
2. Conditions causing immunodeficiency
3. Severe dental disease or chronic infections
4. Amount of soft tissue trauma
5. Bone condition
6. Patient compliance
Dogs having a history of recurrent pyoderma are at a higher risk of developing orthopedic infections postoperatively. Pyoderma screens should be considered prior to clipping and prior to surgery. Overt infections
should be treated and eliminated prior to performing orthopedic procedures. Prophylactic antibiotics are
warranted in these patients. Any disorder or medication that compromises the immune system predisposed
the patient to infection. Examples include endocrine disorders (diabetes mellitus, hypothyroidism, Cushing’s
disease) and drug therapy (corticosteroids, cytotoxic drugs). The effect of such preexisting conditions should
be minimized prior to surgery if possible. Consideration should be given to improving the dental status of
patients or resolving infections at distant sites (e.g. cystitis, otitis) prior to performing elective orthopedic conditions. If orthopedic surgery is mandatory in the face of a potential nidus for infection, prophylactic antibiotics are warranted. In addition, ancillary procedures to treat the distant nidus of infection (teeth cleaning, surgical debridement) should be avoided at the time of orthopedic surgery and delayed to a future date.
Another important patient factor affecting the chance of developing infection is the amount of soft tissue and
bone trauma present. Extensive trauma to soft tissues disrupts host immune defense increasing susceptibility to infection. Devitalized soft tissues and compromised blood supply to these tissues increase risk of infection due inability for immune defense mechanisms to eliminate bacterial insult. Interestingly, severely
comminuted fractures do not increase chance of infection unless the fragments become avascular. The most
common cause of compromised blood supply to fracture fragments is surgical manipulation. Lastly, patients
must not traumatize the surgical site postoperatively. Dogs have a tendency to chew or lick orthopedic
wounds during the first week after surgery. Access to wounds should be prevented with bandages or restrain
devices such as Elizabethan collars.
SURGICAL FACTORS
1. Surgical prep and drape
2. Aseptic technique
3. Surgical approach
4. Antibiotic prophylaxis
5. Surgical technique
6. Implant choice
7. Closure technique
Surgical factors play a major role in the development of orthopedic infections. Strict aseptic technique is
mandatory. Gone are the days of a quick rinse of the hands and gloveless surgery. The surgeon should adhere to proper protocol when scrubbing, gowning and gloving prior to surgery. The patient should be
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clipped atraumatically with clippers just before surgery is to be performed. Clipping several days in advance my irritate the skin and increase the chance of pyoderma. Shaving with a razor after the clip is not
recommended. Injury to the epidermis increases the chance of infection. Benefit may be obtained by
bathing the affected limb with chlorhexidine shampoo daily for 2-3 days prior to surgery. Mupiricin ointment can be applied to the nasal mucosa for 2-3 days prior to surgery to reduce the chance of nosocomial
infection associated with methicillin-resistant Staphylococcus spp. The surgical area should be prepped using proper protocol with effective antiseptics and proper technique. The surgical site should be isolated by
4 surgical towels and towel clamps. An impervious drape should be placed over the towels exposing only
the area to be incised. A second incisional drape can be applied to add further protection against infection.
Incisional drapes (e.g. Ioban drape - 3M products) are available with antiseptics that provide residual antimicrobial activity during surgery. The chance of postoperative infection decreases if the incisional drape
remains adhered to the edge of the skin. Steps that can be taken to improve adherence include spray adhesive, thorough drying of proper scrub agent and suturing the subcutaneous tissues to a stockinette at the
incision edges.
Choice of surgical approach is extremely important and can make the difference between normal healing
and complicated healing due to infection. The surgical approach should be as minimally-invasive as possible to prevent unnecessary damage to blood supply, adjacent soft tissues and bone fragments. Good decision-making and proper planning is essential before beginning surgery to stabilize a fracture. Fractures
should be assessed as to whether they are reducible or non-reducible. Reducible fractures (typically 2-3 total fragments) can be reduced without disruption of the soft tissues attached to the fragments. The fracture
fragments are anatomically reduced being careful to preserve the attached soft tissues. The fracture is then
stabilized with a suitable implant. Non-reducible fractures (typically greater than 3 total fragments) cannot
be reduced anatomically without damaging the soft tissue attachments and blood supply to the bone fragments. Reducible fractures can be approached using traditional approaches with an expectation of normal
healing. Non-reducible fractures are best approached using minimally-invasive approaches that preserve
blood supply to the fragments, accelerate bone healing and decrease the chance of implant failure. The technique of relative fracture reduction is used with non-reducible fractures. Traction is placed on the leg in order to bring it to length. Spatial alignment of the joint above and below is restored, such that the range of
motion of these joints move in the same plane of direction. The fracture is stabilized using a bridging technique without stabilizing the intermediary fragments.
The implants used should be appropriate for the amount and type of force that will be applied during the
convalescence period. Fractures that are inadequately stabilized have excessive motion at the fracture site.
This leads to implant loosening, disruption of neovascularization and fibrous tissue repair rather than osseous repair. Loose implants and vascular compromise are associated with a greater chance of infection.
Surgical closure should be performed in a manner that reduces risk factors for infection. The incisional
edges should be handles meticulously to avoid traumatizing the tissue and damaging blood supply. Dead
space should be minimized. Drains should only be used if absolutely necessary and if so should be of the
closed suction type and they should be maintained with proper aseptic technique. Wounds can be closed
with a variety of suture materials, but monofilament suture is less likely to result in infection. New suture
materials are available (e.g. PDS Plus, Monocryl Plus) that have bacteriocidal activity and these appear to
lessen the chance of infection.
Prophylactic antibiotics are generally recommended in patients that have depressed immunity, damaged soft
tissues, poor blood supply, chronic infection at a distant site, surgical procedures exceeding 90 minutes or
are having implants placed for certain fractures or joint replacement. Prophylactic antibiotics should be administered at the proper dose and tissue levels of the antibiotic should be at therapeutic levels throughout
the duration of surgery. Prophylactic antibiotics have questionable merit in patients having uncomplicated
orthopedic surgery with no risk factors for infection. Flushing the wound or join with antibiotics have little
merit. Antibiotics can be delivered to the tissues at a higher concentration using a vehicle that allows antibiotic elution over a period of time. Vehicles that can be used include ingress drains, antibiotic-impregnated methylmethacrylate and various antibiotic impregnated polymers.
BACTERIAL FACTORS
1. Type of bacterial organism
2. Tendency to produce biofilm
2. Antibiotic susceptibility
3. Ability to reduce bacterial numbers
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Bacterial resistance is developing to most of our common antibiotics. Methicillin-resistant strains of Staphylococcus spp. have become particularly common. Infections associated with this organism are considered
nosocomial in many cases and affected patients may carry the organism as part of their normal flora (eg.
Nasal mucosa or epidermis) or have increased susceptibility. Prophylactic antibiotics should be used judiciously to prevent infection without increasing the opportunity to develop resistant strains. Infected wounds
should be cultured and a sensitivity panel should be run to assess for appropriate antibiotic choice. Contaminated wounds should be aggressively lavaged, preferable with high pressure irrigation. Implants should
not touch the skin. Minimize exposure of implants to air and other tissues until time for implant placement.
Lavage the tissues prior to application of implants to reduce the chance of bacterial colonization. Certain
bacteria have genetic coding that give them the capability to produce bacterial slime or biofilm. Biofilm is a
mucopoylsaccharide film secreted by bacteria that attached to the surface of foreign bodies, including suture
material and metallic implants. Biofilm reduces the ability of the host immune system to eliminate bacterial
contamination. Implant removal is recommended in patients having an implant-related infection. The implant should be removed and cultured after healing is complete.
ENVIRONMENTAL FACTORS
1. Nosocomial bacterial population
2. Aseptic technique
3. Wound protection
4. Postoperative antibiotics
5. Fracture stability
6. Owner and patient compliance
A dirty environment is not conducive to successful surgery. The prep area, surgery theatre, recovery area
and hospitalization area should be clean as possible. Each area should be cleaned between patients. Bedding
should be changed frequently. Bandages that become soiled should be changed immediately. Bacterial surveillance of the environment should be performed 1-6 months depending on the incidence of infection in the
hospital. The need for postoperative antibiotics should be considered carefully. Excessive antibiotic use promotes bacterial infection and may even increase the chance of infection form bacterial or other organisms
such as yeast due to elimination of normal flora of the skin and mucosal membranes. Loss of these less virulent bacterial forms reduces the competition for other more resistant bacterial strains, increasing the chance
for infection. Fracture stability must be maintained for proper healing. Loss of stability leads to loosening of
implants and an increase in infection rate. Owners must be appropriately advised on proper postoperative
care and expectations. Patients must be managed appropriately to ensure good patient compliance.
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Brian S. Beale
Perché questo caso di frattura
è finito male?
36
B.S. Beale
Why did this fracture case go wrong?
Texas (USA)
Comminuted fractures can be especially challenging due to the complexity of the fracture fragments and
concomitant soft tissue injury. Careful consideration should be given to decision-making prior to onset of
fracture repair. Factors that should be considered include mechanical, biological and postoperative compliance. Complex fractures that are treated with a mechanically sound repair often leave the surgeon pondering what could have possibly gone wrong when a “perfect” repair fails. Often times, the answer lies in the
neglect of the biological or postoperative compliance factors. Neurologic function should always be assessed
because complex fractures are often associated with high-energy trauma that also can injure the brachial
plexus or peripheral nerves of the forelimb. This lecture will focus on presentation of clinical cases involving complex fractures of the forelimb and hindlimb, with an emphasis on the decision-making process. A variety of fracture repair techniques will be discussed including interlocking nails, plate-rod construct and linear external fixators. Minimally-invasive surgical approaches reduce pain and minimize trauma to the soft
tissues. Biological factors important for fracture healing are preserved, enhancing the body’s ability for indirect bone healing. The technique can be used with all fracture types, but is particularly useful for stabilization of comminuted fractures. This type of bone healing is also referred to as secondary bone healing,
spontaneous bone healing and callus healing. Stabilization of fractures using the principles of biologic fracture management is performed with the same type of implant systems used with traditional fracture repair,
including externally and internally applied devices.
FRACTURE MANAGEMENT
Comminuted fractures of the extremities can be challenging. It is always a race between a fracture healing
and an implant failing. Steps can be taken to tip the scale in the direction of early fracture healing. These
steps include:
1. minimally invasive surgical approach
2. preservation of soft tissue attachments to bone fragments
3. use of cancellous bone grafts
4. rigid method of fracture stabilization
5. early return to function
It is always important to obtain an accurate history prior to stabilizing fractures. A complete physical exam
and appropriate diagnostic tests should performed. Pathologic fractures are more likely to be seen in the geriatric dog and cat and should be identified preoperatively to ensure proper client education and communication.
INDIRECT BONE HEALING
Biological fracture management utilizes indirect fracture reduction to preserve the soft tissue envelope at the
expense of anatomic reduction. Indirect bone healing occurs as a result. Indirect bone healing consists of
three elements: 1. the formation of granulation tissue at the fracture site 2. fracture gap widening due to resorption of bone ends 3. new bone formation involving formation of a bone callus. Less disruption of the
vascular supply to bone fragments is achieved through minimal handling of the fragments, promoting early callus formation.2,3,6,7 Indirect bone healing is first associated with the formation of fibrous connective tissue and cartilage callus between the fragments.4 Indirect bone healing occurs due to instability at the fracture site and is partially regulated by fragment gap strain.4 Interfragmentary strain is a ratio of change in the
gap width to the total width prior to physiological loading.1,5 A study of the “interfragmentary strain hypothesis” using ovine osteotomy models demonstrated that the initial stages of indirect bone healing occur
earlier and more extensively between gaps with lower shear strain.1 Management of a non-reducible diaphyseal fracture with an implant system that does not utilize anatomical reconstruction and creation of subsequent small fracture gaps avoids high interfragmentary strain, favoring bone healing.
IMPLANT SYSTEMS
External and internal implant systems can be used to achieve bone healing using biological fracture management. Examples of external devices when used in an appropriate manner include casts, splints, linear external fixators and circular fixators. Internal devices commonly used for this application include the platerod system, interlocking nail and bone plates. Other implant systems can also be used for biologic fracture
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management as long as the soft tissue envelope is preserved at the fracture site. Whatever implant system is
used, its application must be possible with minimal or no handling of the comminuted fracture fragments.
External Fixator
External fixators provide rigid stabilization and can be used with minimally-invasive technique. Many fractures of the radius and tibia can be reduced closed and stabilized with an external fixator. The main disadvantage is the potential for complications with premature pin loosening and the added care needed in the
postoperative period. The use of external fixators for fracture repair is not optimal if the patient or owner
is likely to have poor compliance in the postoperative period. External fixators frames can be applied in one
of 3 configurations- linear, circular or as a hybrid of linear and circular.
Plate-rod construct
The plate rod system has been found to be an ideal implant system for biological fracture management.
Management of a non-reducible diaphyseal fracture with a combination of an IM Steinmann pin and bone
plate can be applied without anatomical reconstruction and thus, avoids the development of small fracture
gaps with high interfragmentary strain. The addition of the IM pin to the plate also significantly increases
the construct stiffness and estimated number of cycles to fatigue failure when compared to a plate only construct. An IM pin serves to replace any transcortical defect in the bone column and acts in concert with the
eccentrically positioned plate to resist bending.2 Mathematical analysis of the plate-rod construct in the canine femur demonstrated that the pin and plate act most like a dual-beam structure, assuming slight motion
of the pin in the canal.2 Addition of an IM pin to a bone plate has been shown by Hulse et al. to decrease
strain on the plate two-fold and subsequently increase the fatigue life of the plate-rod construct ten-fold compared to that of the plate alone.1 In the canine femur, plate strain is reduced by approximately 19%, 44%,
and 61% with the addition of an IM pin occupying 30%, 40% and 50% of the marrow cavity, respectively.3
Stiffness of plate-rod repairs may be as much as 40% and 78% greater when the pin occupies 40% and 50%
of the marrow cavity, respectively.2
Locking Plates
Locking plates have become very popular for minimally-invasive fracture repair. Many locking plate systems are available including the Synthes, FIXIN, SOP and ALPS. Locking plates have the ability to lock
the screw into the hole of the plate. The mechanism for locking varies amongst manufactures. The Italian
design FIXIN locking plate system has a conical locking mechanism while the Synthes system has a threaded locking mechanism. The FIXIN plate hole is tapered to
match the conical nature of the head of the screw. This type
of fitting is similar to the Morse taper of the head and neck
fitting of the Total Hip Replacement implant. The stability
of this design is extremely secure. The Synthes locking plate
has threaded holes in the hole of the plate. Corresponding
threads in the head of the screw engage the threads of the
hole, locking the screw to the plate. The ability to lock the
screw to the plate increases pull-out strength of the screw
and construct stability. Traditional plates do not have
threaded holes. Screws placed in ordinary plates apply pressure to the plate, pressing it onto the bone surface. The friction between the plate and the bone provides the stability to
the bone-implant construct. In contrast, the locking plate
achieves stability through the concept of a fixed-angle construct. The locking plate is not pressed firmly against the
bone as the screws are tightened. The locking screws and
plate function more like an external fixator. Locking plates The FIXIN locking plate us- A Synthes locking plate
are essential “internal fixators”. The plate functions as a con- es a conical head to lock into and locking screws were
necting bar and the screw functions as a threaded fixator a matching conical hole in the used to revise the fracpin. The tapered or threaded head of the locking screw en- plate creating fixed-angle sta- ture. The fracture healed
gages the hole of the plate, similar to the clamp of an exter- bilization.
quickly without complinal fixator. The Synthes locking plate also has combi-holes
cation. Locking screws
which allow use of traditional or locking screws when dehave increased pull-out
sired. Traditional screws should be place prior to locking
strength compared to trascrew when using locking plates.
ditional screws.
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B.S. Beale
Locking plates are ideal for minimally-invasive fracture repair for several reasons. Blood supply to the bone
is preserved because the plate is not pressed tightly against the bone. The plate does not require perfect
anatomic contouring because the displacement of the plate will not occur as the screw is tightened into the
hole of the plate. Accurate contouring is difficult with a minimally-invasive approach due to the minimal exposure to the shaft of the bone. Lastly, locking screws give fixed angle support to the non-reduced fracture,
increasing stability and less chance of collapse and instability at the fracture gap.
Interlocking nail
The Deuland interlocking nail system presently available in the U.S. (Innovative Animal Products, Inc., Rochester, MN) is a modified Steinmann pin modified by drilling one or two holes proximally and distally in the pin, which allows the placement of transverse bolts or screws through the bone and nail.
The nail, bolts and screws can be applied in closed or open fashion due to the
incorporation of a specific guide system that attaches to the nail. The equipment needed to place the nail includes a hand chuck, extension device, aiming
device, drill sleeve, drill guide, tap guide, drill bit, tap, depth gauge, and screwdriver. Cost of the system is reasonable and each nail is approximately half the
cost of a comparative bone plate. The nails are available in diameters of 4.0,
4.7, 6, 8 and 10 mm and varying lengths and hole configurations. The 4.0 and
4.7 mm nails use 2.0 mm screws or bolts. The 6 mm nail is available in two
models and will accommodate either 2.7 or 3.5 mm screws or bolts. The 8 mm
nail is also available in two models and will accommodate either 3.5 or 4.5 mm
screws or bolts. The 10 mm nail uses 4.5mm screws or bolts. The solid cross
locking bolts have a larger diameter compared to a similar diameter screw,
thus are less likely to break. Bolts also provide superior mechanical behavior Interlocking nails provide axial,
bending and rotational stability
compared to screws.
The interlocking nail is placed along the mechanical axis of the bone. The in- due to the ability of the screw to
terlocking nail neutralizes bending, rotational and axial compressive forces due lock the IM pin to the bone.
to incorporation of transfixation bolts or screws which pass through the pin and
lock into the bone. This is in contrast to a single intramedullary Steinmann pin
which is only effective in neutralization of bending forces. The interlocking nail has a similar bending
strength compared to bone plates, but is slightly weaker in neutralization of torsional forces. The screws also prevent pin migration, a common complication seen with Steinmann pins.
When using an interlocking nail, the largest diameter nail should be selected that can be accommodated
by the medullary cavity at the fracture site. In most large dogs, an 8 mm nail and either 3.5 or 4.5 mm
screws or bolts can be used in the femur and humerus. In medium-sized dogs, the 6 mm nail and either
2.7 or 3.5 mm screws or bolts are typically used. In small dogs and cats, the 4.7 mm nail and 2.0 mm
screws are typically used. The tibia of medium and large - sized dogs will usually accommodate a 6 mm
nail, but some large dogs will accept an 8 mm nail. Small dogs and some cats will accept a 4.0 mm nail for
repair of tibial fractures.
Dejardin et. al. have developed a novel interlocking nail that provides an angle stable locking mechanism.
The advantage of angle stable locking is the elimination of torsional and bending slack, resulting in reduced
interfragmentary motion. This interlocking nail system provided comparable mechanical performance to a
plate system. Dejardin’s nail is currently unavailable, but release of the nail is expected in the near future.
SURGICAL APPROACH
Closed reduction and stabilization is the optimal method of treatment when possible. Unfortunately, this
method is rarely possible in the senior patient due to the severity of fractures seen, long time until bony
union, and the tendency for patients to develop bandage sores. Open surgical approaches can be either traditional or minimally invasive. The minimally invasive approach has also been described as an “open but
don’t touch” approach. The acronym, OBDT, is used to describe this technique. The advantages to using
an OBDT technique is preservation of vascular supply to the fracture site and thus quicker healing, shorter intraoperative time, less postoperative pain and early return to function. Methods of stabilization that
work well with an OBDT approach include the interlocking nail, plate-rod hybrid and external fixation. The
key feature of a minimally-invasive approach is the preservation of the soft tissue envelope at the fracture
site. Small comminuted fragments will become quickly incorporated into the bony callus if left with a vascular pedicle. Anatomic reduction of small fragments is difficult if vascular supply to the fragment is to remain uncompromised.
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B.S. Beale
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2010, Bologna
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CANINA
A combination of an intramedullary pin and bone plate (plate-rod construct) provides excellent stability of comminuted diaphyseal fractures.
Traction is placed on the limb to bring it to adequate length. The IM
pin is then placed to align the fragments and give bending stability. The
bone plate and screws are placed to provide rotational and axial stability as well as additional bending strength.
Pre-op
Post-op
7 week
15 week
Comminuted fractures can be managed biologically using an interlocking nail, shortening surgical time and speeding bony union.
BONE GRAFTS
Numerous sites for harvest of cancellous bone graft have been described in the dog, but the most practical
are the greater tubercle of the humerus, wing of the ilium and the medial, proximal tibia. The humerus provides the greatest amount of cancellous bone, but the ilium and tibia provide sufficient amounts for most applications. All of these sites are readily accessible, have easily recognizable landmarks, have little soft tissue
covering, and provide relatively large amounts of cancellous bone. The greater trochanter can also be used if
other sites are not available; however, the yield of cancellous bone is markedly less. Occasionally multiple
sites are required to harvest sufficient quantities of bone to fill large bone defects or during arthrodesis.
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B.S. Beale
Minimal instrumentation is required for harvest of cancellous bone graft. Basic surgical instruments are used
to approach the site selected for harvest. A hole is drilled through the near cortex using either a drill bit,
trephine or trocar-pointed pin. A curette is used to scoop the graft out of the metaphyseal cancellous bone.
The cancellous bone should be scooped out in large clumps if possible. Use a curette that can be comfortably manipulated in the medullary cavity; I prefer to use a relatively large curette as this speeds harvest and
reduces trauma to the graft. Closure is performed routinely in 2-3 layers. Recently, a technique was described using an acetabular reamer to harvest large amounts of corticocancellous bone graft from the lateral surface of the wing of the ilium.
The graft collected should be handled gently. It is desirable to collect the graft immediately prior to usage.
This increases the osteogenic properties of the graft. As graft is harvested, it should be placed on a bloodsoaked gauze until transfer to the recipient site. Extreme care should be taken to store the graft properly; do
not accidentally discard the graft due to misidentification of the gauze as being used. The graft should be
atraumatically packed into the recipient site. Lavage of the site should be avoided after the graft is placed.
REFERENCES
1.
2.
3.
4.
5.
6.
7.
Cheal EJ, Mansmann KA, Digioia III AM, Hayes WC, Perren SM. Role of interfragmentary strain in fracture healing: ovine model of a healing osteotomy. J Orthop Res 1991; 9: 131-142.
Hulse D, Hyman W, Nori M, Slater M. Reduction in plate strain by addition of an intramedullary pin. Vet Surg
1997; 26: 451-459.
Hulse D, Ferry K, Fawcett A, Gentry D, Hyman W, Geller S, Slater M. Effect of intramedullary pin size on reducing bone plate strain. Vet Comp Orthop Traumatol 2000; 13:185-90.
Johnson AL, Egger EL Eurell JC, Losonsky JM. Biomechanics and biology of fracture healing with external skeletal fixation. Compend Contin Educ Prac Vet 1998; 20 (4): 487-502.
Johnson AL, Seitz SE, Smith CW, Johnson JM, Schaeffer DJ. Closed reduction and type-II external fixation of comminuted fractures of the radius and tibia in dogs: 23 cases (1990-1994). JAVMA 1996; 209 (8): 1445-1448.
Palmer, RH. Biological Osteosynthesis. Veterinary Clinics of North America: Small Animal Practice 1999; 29 (5):
1171-1185.
Palmer, RH. Fracture-patient assessment score (FPAS): a new decision-making tool for orthopedists and teachers.
6th Annual American College of Veterinary Surgeons Symposium, San Francisco, 1996: 155-157.
41
Tim W.R. Briggs
Prof, MD(Res), MCh(Orth), FRCS
Consultant Orthopaedic Surgeon Joint Head of
Training, RNOH & Joint Medical Director
Royal National Orthopaedic Hospital, Brockley
Hill, Stanmore, Middx. HA7 4LP
STATE OF THE ART LECTURE
Ricostruzione cartilaginea con ACI
(Autologous Chondrocyte
Implantation) e MACI
(Matrix-induced Autologous
Chondrocyte Implantation): hanno
resistito alla prova del tempo?
42
Cartilage resurfacing with ACI and MACI:
have they stood the test of time?
Tim W.R. Briggs, Prof., MD(Res), MCh(Orth), FRCS
Consultant Orthopaedic Surgeon Joint Head of Training, RNOH & Joint Medical Director
Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middx. HA7 4LP
Chondral damage to the knee is common and, if left untreated, can proceed to degenerative osteoarthritis.
In symptomatic patients established methods of management rely on the formation of fibrocartilage which
has poor resistance to shear forces. The formation of hyaline or hyaline-like cartilage may be induced by implanting autologous, cultured chondrocytes into the chondral or osteochondral defect.
Autologous chondrocyte implantation may be used for full-thickness chondral or osteochondral injuries
which are painful and debilitating with the aim of replacing damaged cartilage with hyaline or hyaline-like
cartilage, leading to improved function. The intermediate and long-term function and clinical results are
promising.
This talk provides a review of autologous chondrocyte implantation and describes our experience with this
technique at the Royal National Orthopaedic Hospital in the U.K.
The procedure is shown to offer statistically significant improvement with advantages over other methods
of management of chondral defects.
43
Sorrel Langley-Hobbs
MA, BVetMed, Dipl SAS(O), Dipl ECVS,
MRCVS, Cambridge (UK)
Zoppie posteriori nel gatto:
che cosa è se non è una frattura
né un ascesso?
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Feline hind limb lameness what if it’s not a fracture or an abscess?
Sorrel Langley-Hobbs MA, BVetMed, Dipl SAS(O), Dipl ECVS, MRCVS
Cambridge (UK)
Osteosarcoma
The incidence of bone tumours in cats is reported to be 3.1 per 100,000 cases. The most common bone tumour is osteosarcoma (OSA), accounting for approximately 70% of all primary tumours (Bitteto et al 1987).
Older cats are usually affected (mean age 10 years) and the tumour appears to have a predilection for the
metaphysis of the long bones of the hind limb and the pelvis. OSA of the appendicular skeleton of the cat
behaves in a much less aggressive fashion than its canine counterpart. The metastatic rate is relatively low,
1 in 19 cases in one study (Quigley & Leedale 1983); and because wide margins can be achieved by amputation the prognosis for long survival times is good. OSA of the axial skeleton carries a less favourable prognosis because the site of the tumour often precludes complete surgical removal. Radiographic features of feline OSA are variable, lesions of the long bones are predominantly metaphyseal and lytic.
THE HIP
Hip dysplasia
Hip dysplasia in cats may be detected as an incidental finding when the pelvis or abdomen is radiographed
for other reasons. The lower incidence, or detection rate, is related to the smaller size and varied genetic
background of cats. In addition different clinical signs are exhibited. Pure-bred cats may be predisposed. In
one study the incidence was reported to be 6.6% (Keller et al 1999). Radiographic signs in cats included
more acetabular remodelling with minimal femoral neck changes. A study performed at the University of
Pennsylvania confirmed that cats have high hip joint laxity and there is a relationship between DJD and laxity in the hip joint of cats (Langenbach et al 1998).
Slipped capital femoral epiphysis (metaphyseal osteopathy)
This condition is seen mainly in young male neutered cats, aged 2 years or less. Affected cats present with
unilateral hind limb lameness often of insidious onset. Radiographs show a slipped femoral epiphysis, there
may be ‘apple coring’ of the femoral neck (Queen et al 1998). This is a hypervascular response associated
with attempts to repair the fracture. Biopsies of the affected femoral neck showed evidence of fracture healing. In some cases the fracture has healed but a malunion is present. One review of 26 adult cats with spontaneous femoral capital physeal fractures suggested that they were most likely to be heavier, neutered males
with delayed physeal closure (McNicholas et al 2002). Treatment is femoral head and neck excision. The
other femoral head may slip or fracture at a later date.
Hip luxation (dislocation)
The hip is the most commonly dislocated joint in the cat. The luxation usually occurs in a dorsocranial direction, mainly due to the pull of the gluteal muscles. Lameness may vary from non-weight bearing to mild
with some external rotation of the foot. Manipulation, palpation and comparison of leg length can aid in diagnosis, however fractures in this area can have similar clinical findings. Definitive diagnosis is by radiography – lateral and ventro-dorsal extended. It is best to radiograph the hip joint prior to attempting closed
reduction, if fracture fragments are present or the cat has hip dysplasia / DJD or another traumatic injury
then closed reduction is unlikely to be successful.
Treatment options include closed reduction, conservative, transarticular pin, ilio-femoral suture and femoral
head and neck excision amongst others. The transarticular pin is a useful method of hip stabilisation in the
cat, and the commonest technique we employ (Sissener et al 2009). 1.6mm K wires are used, and left in temporarily for 2-4 weeks, the duration is mainly dependant on the presence of other injuries. The prognosis is
good for maintenance of reduction, except in bilateral cases where reluxation of one hip is likely. Conservative treatment is an option in cats where cost is an implication, however stiffness is likely.
Myositis ossificans
A generalised form affects skeletal muscle and connective tissue. Young cats with this disease present with
weakness, stiffness, decreased limb movement and muscle pain. Calcified masses can be palpated in muscles.
Radiographs reveal extensive soft tissue mineralisation. There is no effective treatment for the generalised form
45
S. Langley-Hobbs
and prognosis is poor (Norris et al 1980). The localised form has a better prognosis and at CUVS we have
seen three cats with progressive myositis ossificans affecting the semitendinosus / biceps femoris musculature.
THE STIFLE
Cranial cruciate ligament disease
Cats do suffer cranial cruciate ligament disease (Harasen 2005). There are two main forms, traumatic and
degenerative. In the traumatic form there is usually damage to other structures such as the collateral ligaments and menisci (stifle derangement). Cats with degenerative cranial cruciate ligament ruptures (or the occasional isolated traumatic rupture) will have hind-limb lameness, stifle joint swelling and the cranial drawer test will be positive. Radiographs of affected stifles will show compression of the infra patella fat pad associated with a joint effusion. Dystrophic mineralisation can be seen especially in older animals (Reinke &
Mughannam 1994, Whiting & Pool 1985). In Reinke & Mughannams (1994) paper they report on six spayed
female cats, five of which had a cruciate rupture. The lameness resolved after cruciate surgery and calcification resection. Mineralisation may also be present in the normal stifle.
Treatment of cranial cruciate ligament rupture in cats is either conservative or surgical. In one study where
18 cats were treated conservatively they took an average of five weeks to regain normal gait (Schrader &
Scavelli 1987). Surgery may have the advantage of offering a quicker return to function. Generally extracapsular stabilisation techniques are suitable and the prognosis is good. Tibial plateau levelling procedures
have been performed in some cats. It is important to check affected cats carefully for concurrent disease. In
one paper three cats with cranial cruciate ligament rupture were all operated with an extracapsular technique, all died within 2 weeks of surgery with cardiomyopathy. The author advised ECG and thoracic radiographs prior to surgery or that the cats be treated conservatively (Janssens et al 1991). The author has
also seen two cats with cranial cruciate ligament rupture that had concurrent hepatopathy.
The deranged stifle
Disruption of the stifle after trauma in the cat is not uncommon. Often both cruciate ligaments are disrupted, together with one, or both, collaterals, and meniscal detachment. The joint is highly unstable and conservative treatment is not appropriate, it is therefore important to differentiate these more severe injuries
from an isolated cranial cruciate ligament injury. The options for management are either to individually repair the affected collateral, reattach the meniscus, and the cranial (and caudal cruciate) ligament or to effectively reduce the dislocation and place a transarticular pin. In seven cats where a transarticular pin was used
for deranged stifles the results were excellent in 4, fair in 2, and poor in one (Welches & Scavelli 1990). Complications included pin loosening & bending. These were possibly as a result of inadequate external coaptation. Bruce (1999) reported on the use of TESF after reconstruction of individual ligaments in four cats.
There were serious complications with fractures occurring through ESF pin-holes when cats were not confined indoors, otherwise the method was successful in terms of stabilising the stifle.
Patella luxation
Patella luxation is not common in cats, when it occurs it is generally medial and can be uni or bilateral. Both
traumatic and developmental (congenital) forms are seen. The condition has been reported in the Devon
and Cornish Rex, Persian and Abyssinians as well as domestic short-haired breeds (Engvall 1990). Houlton
and Meynard (1989) report on 8 cats with patella luxation, six of which had bilateral disease. Conservative
treatment was unsuccessful but there was a ninety percent improvement with surgery. One patella fracture
occurred 6 months post operatively.
Patella fracture
These are usually stress fractures in cats. They are generally seen in young cats between one and two years
of age and in over half the cases they are bilateral with a median interfracture gap of 3 months. The fractures rarely heal and pin and tension band wire fixation should not be used as it results in further fracturing of the brittle bone. Circumferential wiring, tension band wiring (without a pin) or conservative treatment
can all be used but which is the best treatment has not been fully determined. Chronic non-union fractures
can be seen in older cats.
THE HOCK
Scottish Fold Osteochondrodysplasia
The Scottish fold breed of cat derived from a DSH crossed with a Scottish farm cat with folded ears. The
folded ears are a sign of defective collagen / cartilage. Some cats have associated osseous deformity with
ankylosis of the hindlimb, joints and tail. In one case report the cat had bilateral hind-limb lameness, asso46
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ciated with tarsal exostoses. Lameness resolved following staged bilateral ostectomies and pantarsal
arthrodeses. (Mathews et al 1995).
Collateral ligament injuries
Traumatic hock injuries are common and usually associated with fractures (Roch et al 2009). Most commonly there is fracture of the lateral malleolus (fibula) alone or with a concurrent fracture of the medial
malleolus, most rare is bilateral ligament rupture without fracture. When avulsion fractures are present these
should be staibilised with pin and tension band wire and external coaptation or transarticualr external skeletal fixation. Occasionally cats will present with hind limb lameness associated with closed collateral ligament
injury, sometimes just the short collateral ligament may be ruptured. Repair is necessary with closed injuries
– primary repair is often difficult and use of a prosthetic ligament is recommended, Anchorage of prosthetics is challenging in the cat given the small size.
Periosteal proliferative polyarthritis
PPP is a form of Immune-based arthritis reported by Pedersen (1980). It generally affects male cats and has
a guarded prognosis for recovery. It mainly affects hocks and carpi. Radiographically there are erosive
changes in the joints and enthesopathies. Possible viral association but unconfirmed.
REFERENCES
Bitetto WV, Patnaik AK, Schrader SC Mooney SC. Osteosarcoma in cats: 22 cases (1974-1984) J Am Vet Med Assoc
1987;190:91-93.
Bruce W.J. Stifle joint luxation in the cat: treatment using transarticular external skeletal fixation. J Small Anim Pract
1999;40(10):482-8.
Engvall E. Patella luxation in abyssinian cats. Fel Pract 1990;18(4):20-22.
Harasen GL Feline cranial cruciate rupture: 17 cases and a review of the literature. VCOT 2005 18(4) 254-7.
Houlton J.E.F & Meynink S.E. Medial patella luxation in the cat. J Small Anim Pract 1989;30:349-353.
Janssens L.A.A., et al. Anterior cruciate rupture associated with cardiomyopathy in three cats. Vet Comp Orth Traum
1991;4:35-37.
Keller GG, Reed AL, Lattimer JC, Corley EA Hip Dysplasia: a feline population study. Vet Radiol Ultrasound. 1999;
40:460-4.
Langenbach A, et alSmith G. Relationship between degenerative joint disease and hip joint laxity by use of distraction index and Norberg angle measurement in a group of catsJAVMA. 1998 Nov 15;213(10):1439-43. Erratum in: J Am
Vet Med Assoc 1999 Mar 1;214(5):659.
Mathews KG, et al. Resolution of lameness associated with Scottish fold osteodystrophy following bilateral ostectomies
and pantarsal arthrodeses: a case report. J Am Anim Hosp Assoc. 1995 Jul-Aug;31(4):280-8.
McNicholas WT Jr, Wilkens BE, et al. Spontaneous femoral capital physeal fractures in adult cats: 26 cases (1996-2001).
J Am Vet Med Assoc. 2002 Dec 15;221(12):1731-6.
Norris AM, Pallett L, and Wilcock B. Generalised myositis ossificans in a cat. Journal of the Am Anim Hosp Assoc
1980;16:659-663.
Pederson NC, Pool RR. Feline chronic progressive polyarthritis. Am J Vet Res 1980;41: 522-535.
Queen J, Bennett D, et al. Femoral neck metaphyseal osteopathy in the cat. Vet Rec. 1998 Feb 14;142(7):159-62.
Quigley PJ, Leedale AH. Tumours involving bone in the domestic cat: a review of 58 cases. Vet Path. 1983;20:670-686.
Reinke J.D. Mughannam A. Meniscal calcification and ossification in six cats and two dogs. JAAHA 1994;30:145-152.
Roch SP, St√∂rk CK, Gemmill TJ, Downes C, Pink J, McKee WM. Treatment of fractures of the tibial and/or fibular
malleoli in 30 cats. Vet Rec. 2009 Aug 8;165(6):165-70.
Scavelli, T.D. & Schrader, S.C. Nonsurgical management of rupture of the cranial cruciate ligament in 18 cats. JAAHA
1987;23:337-340.
Sissener TR, Whitelock R, Langley-Hobbs SJ Long term results of transarticular pinning for surgical stabilisation of coxofemoral luxation in 20 cats. JSAP 2009, 50, 112-7.
Whiting P.G. & Pool R.R. Intrameniscal calcification and ossification in the stifle joint in three domestic cats. JAAHA
1985;21:579-583.
Welches, C.D. & Scavelli T.D. Transarticular pinning to repair luxation of the stifle joint in dogs and cats: a retrospective
study in 10 cases. JAAHA 1990;26: 2077.
47
Zoppie anteriori nel gatto:
che cosa è se non è una frattura
o un ascesso?
48
S. Langley-Hobbs
Feline forelimb lameness what if it’s not a fracture or an abscess?
Cambridge (UK)
Osteoarthritis
Cats commonly suffer from osteoarthritis however the clinical signs tend not to be as pronounced as in dogs
(Lascelles 2010). Cats tend to sleep more, exercise less, resent handling and have difficulty jumping up or
down. Osteoarthritis seems to be more common in the forelimb as compared to the hind limb with some
studies showing over representation in the shoulder and elbow in the older cat.
Treatment - It is difficult to modify a cats’ exercise, but it is useful to encourage some movement at regular
intervals during the day. Weight loss is to be encouraged. The use of NSAIDs is restricted because of potential for toxicity and the lack of licensed drugs available. Meloxicam, robenacoxib, ketoprofen & carprofen are all licensed for use in the cat but meloxicam is the only one for long-term (28d) use.
Infective arthritis
Bacterial - The commonest source of infective arthritis in a cat is from a bite, often by another cat. Generally only a single joint is affected, that is hot, swollen and painful, careful examination may reveal a puncture
wound. The most useful investigation is to perform arthrocentesis and synovial fluid analysis. Staphs, streps
and Pasteurella are some of the commonest isolates.
Septic polyarthritis is also occasionally recognised in kittens from an infected umbilicus; joint abscessation
and severe joint destruction can occur in which case euthanasia is recommended (Bennett 2000). Arthritis
associated with bacterial L-forms - Cats with pyogenic subcutaneous abscesses and arthritis associated with a
probable bacterial L-form, a cell wall deficient bacteria) were described by Carro et al (1989). The organism
is difficult to culture, resistant to most antibiotics except tetracycline and can cause severe joint destruction.
Mycoplasmal arthritis - Polyarthritis associated with mycoplasmal infection has been reported in old debilitated cats. Organisms can be cultured on special media or seen with stains such as Giemsa. Gunn Moore et al
(1996) reported one cat that presented with unilateral elbow arthritis associated with tuberculosis, diagnosed
by biopsy.
Calicivirus arthritis - A fleeting stiffness, soreness and lameness with high fever has been reported in young kittens (Pedersen 1983). The prognosis is good as the disease is usually self-limiting. Corticosteroids can be given in protracted cases (Dawson et al 1992)
Lyme Disease Borrelia burgdorferi - Cats can become infected and seroconvert but there is disagreement as to
whether they suffer clinical disease (Bennett 2000).
Immune-based arthritis
Several different types have been reported to affect cats. They usually cause chronic active synovitis in a bilaterally symmetrical fashion. Clinical signs - generalised stiffness, reluctance to jump and exercise. Systemic
signs such as pyrexia, malaise, inappetance can also be present. Immune based arthritis is distinguished from
other types of arthritis by synovial fluid analysis. There are two main categories – erosive and non-erosive.
Erosive inflammatory arthritis
Rheumatoid arthritis - A chronic progressive and destructive arthritis
Periosteal proliferative polyarthritis (Pedersen 1980) - generally affects male cats. Mainly affects hocks and
carpi with erosive changes in joints and entheseopathies. Possible viral association but unconfirmed.
Non erosive inflammatory arthritis
Systemic lupus erythematosus - Polyarthritis may be seen as one feature of a multisystemic disease.
Idiopathic Polyarthritis - Any cases of polyarthritis that do not satisfy the criteria for the joint diseases listed above are be categorised as idiopathic polyarthritis.
Treatment for most of the immune based arthritides is usually with steroids, often prednisolone.
THE SHOULDER
Anatomy
The feline shoulder joint has some anatomical differences from the canine. The metacromion is located on
the distal scapular spine and extends caudally, the coracoid process forms a prominent extension from the
rim of the glenoid craniomedially and a clavicle is present
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Scapular avulsion
There are two case reports of scapular avulsion in cats in
the literature (Leighton 1977, Schneck 1975). Avulsion of
the scapula is a rare injury. Diagnosis is based on palpation and observation of the dorsal displacement of the
scapula. Fracture of the body of the scapula may coexist.
Repair can be achieved by reattaching the bone to the
serratus ventralis muscle with non-absorbable sutures secured through small holes in the scapula. If the soft tissue repair is tenuous a wire can be placed carefully
around an adjacent rib. The cat needs cage rest and / or
bandaging for several weeks post operatively.
Shoulder dislocation
Shoulder dislocation is very rare in the cat and there is very limited information available in the literature.
Reduction is often easily achieved with closed manipulation. A velpeau like sling is recommended for medial luxations and a spica splint, with the shoulder held in slight abduction, for lateral luxations. If reduction is unstable then collateral ligament replacement alone or combined with a temporary transarticular pin
or wire mattress suture can be used (voss et al 2009).
Accessory centres of ossification
Accessory centres of ossification are often seen on the caudal and medial aspect of the glenoid in the cat.
These are presumed to be incidental findings and not fracture fragments or joint mice. They are generally
recognised when the cats are being radiographed for other reasons and not for lameness (often seen on thoracic radiography).
Osteochondritis dissecans of the shoulder joint in the cat
There are two reports in the literature of cats presenting with OCD like shoulder lesions (Butcher and
Beasley 1986, Peterson 1984). One cat was a nine-month Burmese with sudden onset shoulder lameness, a
one centimetre lesion of discoloured articular cartilage was removed from the caudal aspect of the humeral
head at surgery. The other case was a one-year old male neutered cat and a flap of cartilage was removed
from the humeral head after which time the lameness resolved.
THE ELBOW
Anatomy
In the cat there is a supracondylar foramen that contains the median nerve and brachial artery; the supratrochlear foramen is not completely penetrated in the cat. Interrelationship of the ligaments to the proximal
radius & ulna are of particular interest in the cat (Kramers 1992). The elbow joint surface extends cranially
over the edge of the radial head to form a triangular facet similar in size to the large hook-shaped medial
coronoid process of the ulna. These two structures are intimately suspended in a ‘radial oblique’ (annular*)
ligament and an ulnar oblique (anterior medial collateral ligament*) ligament. This suspensory apparatus is
reinforced by an anterior coronoid (ant. oblique*) ligament. Extension, supination and pronation are limited by the inter-locking mechanism of the cranial facet of the proximal radius with the large medial coronoid
process of the ulna within this suspensory apparatus. This function seems ideally adapted for the agile jumping catching and climbing in cats. Attempts should be made to preserve full antebrachial function in feline
trauma patients.
Synovial cysts
Three cats with cystic extensions of the elbow joint capsule were described by Stead and others (1995), one
cat was reported in a case series by Prymak and Goldschmidt (1991) and another in a ‘Whats your diagnosis’ by White et al (2004). In only one cat was surgical excision successful (Prymak & Goldschmidt 1991)
in the other three cats the condition was only temporarily alleviated by surgical excision or drainage, and it
was associated with osteoarthritis. Average age of the cats was 14 years. Diagnosis was assisted by synoviocentesis, ultrasonography & arthrography. The cause of the cysts is unknown but in man it has been theorised that they are related to herniations of joint capsule, inflammation and osteoarthritis.
* Nomenclature of analogous structures in the dog.
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Elbow dislocation
In a survey of feline orthopaedic injuries the elbow joint accounted for approximately 15% of all luxations
seen (Schrader 1994). Lateral dislocation is the commonest but caudal dislocation is seen with a much higher frequency in cats than in dogs. Small fractures of the radial head and anconeal process may be present
but these rarely interfere with reduction and fixation.
Closed reduction is usually possible. Following reduction external reduction should be applied with the
limb held in the position that affords the most stability.
With lateral dislocation full extension usually affords the most stability, extension can be maintained with
an over the shoulder spica splint. With caudal dislocation moderate flexion is usually best. External coaptation should be maintained for 14 to 21 days, however if the reduction is unstable open reduction and internal fixation are indicated. Soft tissue reconstruction may not be adequate and temporary transfixation
with a Kirschner wire or TESF may be indicated. It is particularly important to repair the humeroulnar
collateral ligament in cats (Voss).
Cranial luxation of the radial head in cats
Denny and Butterworth (1999) report that cranial luxation of the radial head associated with rupture of the
annular ligament is occasionally seen in cats. Open reduction is performed and the radial head fixed to the
ulna with a lagged bone screw. Normal function seems to be regained without requiring the screw to be removed.
Osteochondromas
At CUVS several cats have been seen with ‘osteochondromas’ affecting one or both elbow joints. Hubler
and others (1986) report on one cat with similar lesions and one cat with lesions resembling synovial osteochondromatosis. Interestingly 4 of the 6 affected cats were Burmese. The prognosis for appendicular osteochondromas seems to be better than that for axial osteochondromas where affected animals are often
FeLV positive and euthanasia is usually performed.
Hypervitaminosis A
Chronic hypervitaminosis A can result in the formation of exostoses at the site of tendon, ligament and joint
capsule attachments. The cervical spine is most commonly affected but the forelimbs and particularly the elbow joints can also be involved. Affected animals may present with lameness as one of the clinical signs.
THE CARPUS
Hyperextension injury
Carpal hyperextension injury in cats is uncommon. Occasionally young cats / kittens are presented with bilateral hyperextension – this condition may be temporary and it is worth trying conservative treatment initially. A cat with a true traumatic hyperextension injury was treated by pan carpal arthrodesis (Simpson &
Goldsmid 1994).
An anatomical study of the carpus determined that 1.5mm screws should be used in the third metacarpal
bone and 2 mm screws in the distal radius. It may be preferable to fuse the joint at a slightly hyperextended angle as compared to dogs.
Luxation of the radial carpal bone in a cat
A case of radial carpal bone luxation in the cat and its management has been described (Pitcher 1996). Open
reduction was performed in combination with repair of rupture of the short radial collateral ligament and
joint capsule. The carpus was supported for one month following surgery by application of transarticular
external fixation.
Four months after treatment the cat was sound, despite evidence of degenerative joint disease. The mechanism of luxation appears to be analogous in the cat to that seen in the dog.
Carpal luxation
Only two cases of carpal luxation and treatment have been published (Voss et al 2004, Shales & LangleyHobbs 2005), despite its common occurrence after high-rise injury. In the one case the luxation was palmar
and associated with medial collateral ligament rupture, treatment was achieved by medial collateral ligament
repair. In the other case luxation was dorsal with radio-ulnar subluxation due to rupture of the radio-ulnar
ligament. It was treated by closed reduction, primary repair of ligamentous structures and TESF for 5
weeks. Compared to dogs pancarpal arthrodesis is not always required as the palmar fibrocartilage and ligaments seem to be damaged less frequently.
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REFERENCES
Denny H.R., and Butterworth S.J., A guide to canine and feline orthopaedic surgery. 4th edition. Blackwell Science. 1999.
Bennett D.B. Arthritis and Miscellaneous Joint Conditions. In: Feline Orthopaedics and Traumatology. BVOA meeting
11th-12th November 2000;102-104.
Butcher R., Beasley K, Osteochondritis dissecans in a cat? Vet Rec 1986 118 23 646.
Carro T, Pedersen NC, Beaman BL, Munn R. (1989) Subcutaneous abscesses and arthritis caused by a probable bacterial L form in cats. J Am Vet Med Assoc 194 1538-8.
Dawson S. et al Investigations of vaccine reactions and breakdowns following feline calcicivirus vaccination. Vet Rec
1992;132: 346-350.
Farrell M, Thomson DG, Carmichael S. Surgical management of traumatic elbow luxation in two cats using circumferential suture prostheses. Vet Comp Orthop Traumatol. 2009;22(1):66-9.
Farrell M, Draffan D, Gemmill T, Mellor D, Carmichael S. In vitro validation of a technique for assessment of canine and
feline elbow joint collateral ligament integrity and description of a new method for collateral ligament prosthetic replacement. Vet Surg. 2007 Aug;36(6):548-56.
Gunn-Moore D.A., et al Feline tuberculosis. Vet Rec 1996 138 53-58.
Kramers P.C., The feline elbow: special features of bones and ligaments. ECVS 1992 Scientific abstracts.
Lascelles D Feline Degenerative Joint Disease Veterinary Surgery 39 2-13, 2010.
Montavon PM, Voss K, Langley-Hobbs SJ. In Feline Orthopaedic surgery and musculoskeletal disease. Saunders Elsevier 2009.
Paterson M.E. et al Acromegaly in 14 cats. J Vet Int Med 1990;4: 192-201.
Pederson NC, Pool RR. Feline chronic progressive polyarthritis. Am J Vet Res 1980;41: 522-535.
Pederson N.C. et al. A transient febrile limping syndrome of kittens caused by two different strains of feline calicivirus.
Fel Pract 1983;13(10): 26-35.
Peterson C.J., Osteochondritis dissecans of the humeral head of a cat. New Zealand Veterinary Journal 11984 32 7 115116.
Pitcher GD. Luxation of the radial carpal bone in a cat. J Small Anim Pract. 1996 Jun;37(6):292-5.
Prymak C. and Goldschmidt M.H. (1991) Synovial cysts in five dogs and one cat. JAAHA 27 151-154.
Schrader S.C., Orthopaedic surgery Ch 49. In The cat diseases and clinical management. Second edn. Ed R.Sherding
Churchill Livingstone, New York p1651.
Shales CJ, Langley-Hobbs SJ. Dorso-medial antebrachiocarpal luxation with radio-ulna luxation in a domestic shorthair.
JFMS 2006(8) 197-202.
Simpson D, Goldsmid S 1994 Pancarpal arthrodesis in a cat: a case report and anatomical study VCOT 7 45-50.
Stead A.C. et al., Synovial cysts in cats. JSAP 36 450-454.
Voss K, Geyer H, Montavon PM Antebrachiocarpal luxation in a cat. VCOT 2003 (4) 266-270.
White JD, Martin P, Hudson D, Clark A, Malik R. What is your diagnosis? Synovial cyst in a cat. J Feline Med Surg.
2004 Oct;6(5):339-44.
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Il trattamento
conservativo delle fratture
e il contenimento esterno
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Conservative management and external coaptation
of fractures
Cambridge (UK)
This presentation and accompanying notes aim to cover the principles of both conservative management
and external coaptation of fractures and when such methods of fracture management are indicated or contraindicated.
CATEGORIES OF METHODS OF FRACTURE FIXATION
1. Conservative Management
2. External Coaptation
3. External Skeletal Fixation with or without open fracture reduction & repair
4. Internal Fixation – using pins, bone plates, interlocking nails etc
THE PRINCIPLES OF FRACTURE FIXATION
The main objective when dealing with a fracture is to try and return the patient to normal function as soon
as possible. Circumstances must be created which allow bone healing to be optimal.
Non-surgical management has the potential advantages of:
• reducing anaesthetic time,
• avoiding the need for an open surgical approach,
• cheaper materials
• more economic overall.
Non surgical management has the potential disadvantages of:
• fracture disease
• providing insufficient instability resulting in a delayed union or non union
• cast sores – morbidity
• insufficient fracture reduction resulting in a malunion
Non-surgical management includes:
• conservative (cage rest etc) and
• external coaptation (coapt = to approximate)
The aim with conservative treatment is that the surrounding soft tissues (muscle, periosteum and adjacent
bones) will provide enough stability to keep the bones in reasonable alignment whilst healing occurs. Fractures suitable for conservative treatment include stable undisplaced fractures, greenstick fractures and selected fractures of the pelvis, scapula or vertebrae where strong muscular forces act to immobilise the fracture fragments. If the anatomical displacement is acceptable then this is a reasonable option in some of these
cases. Management usually involves a period of restricted activity with confinement to a cage or room. Restriction time varies according to the severity of the fracture and age of the patient. It is usually 4 – 6 weeks
for most fractures. Prevention of weight bearing may be useful for scapula fractures by using a carpal flexion bandage or velpeau sling.
The aim of external coaptation is that compressive forces are transmitted to the bones by means of the interposed soft tissues. Pressure must be evenly distributed throughout the cast or splint to avoid circulatory
stasis. For successful external coaptation the joint above and below the fracture should be immbilised. This
principle extends usually to all the joints distal the fracture (to prevent foot swelling). So for tibial fracture
the cast is extended from the foot to proimal to the stifle, for antebrachial fractures the cast extends from the
foot to proximal to the elbow.
Fractures suitable for external coaptation include fractures distal to the elbow or shoulder, stable fractures
with at least 50% overlap of fracture fragments on orthogonal radiographs. Fractures of just the radius with
an intact ulna or similarly fractures of the tibia with an intact fibula can also be suitable for external coaptation. When 2 or fewer metacarpal or metatarsal bones are fractured cast fixation can be considered. Consideration should also be taken of the:
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• Age - Immature animals (< 6 months) are often suitable candidates given their rapid healing times.
• Breed of dog – it may be easier to keep a cast on a long legged dog than a brachiocephalic breed. Toy breeds
are renowned to develop non-union fractures of the radius and ulna if these are treated with external
coaptation.
• Function of the dog – conservative treatment may be suitable for certain fractures in pet dogs however for
racing or working dogs internal fixation may be advisable – e.g. caudal acetabular fractures.
CAST APPLICATION
Casts tend to be preferable to splints for anything that needs to stay on for more than a week. The ‘Cambridge way’ is to place a double layer of stockinette followed by a layer or two of SofbanÔ(Smith & Nephew)
or a similar water repellant compressible material. Care is taken not to apply too much padding over pressure points such as the point of the hock / os calcaneus, use of a “doughnut” or underpadding pressure
points is preferable. Then I generally use VetcastÔ (Smith & Nephew) with a minimal of 6 layers (3 times
up and down with a 50% overlap) or more in large, active dogs or where there is an acute angle in the cast
(at the hock). Then the cast is bivalved (split in two) and taped immediately back together with strips of zinc
oxide and the whole lot covered in VetrapÔ (Smith & Nephew). The cast extends from the foot to proximal
to the elbow or stifle. The middle two toe-nails and pads should be visible, so the cast can be checked for
slippage, toe swelling etc. If the foot swells the toe -nails will tend to splay outwards.
FRACTURE DISEASE
This occurs during the time necessary for the bone to heal and is a result of immobilisation or decreased
weight bearing of the affected leg.
Typically it includes:
1. joint stiffness,
2. muscle atrophy,
3. osteoporosis,
4. muscle contracture and fibrosis
Fracture disease can be minimised or avoided by aiming for a fast return to weight bearing and avoiding unnecessary immobilisation by external coaptation (casts / splints / bandages). Fracture disease will occur due
to the period of enforced joint immobilisation whilst the fracture heals. Some fractures suitable for external
coaptation may also be suitable for minimal surgical intervention and ESF. ESF preserves joint mobility,
avoids the need for replacing casts that have been outgrown, been chewed or got wet. ESF will often provide better immobilisation of fragments, giving more pain reduction and therefore better use of the leg.
Fractures that are not ideally suitable for conservative treatment or external coaptation include
• Articular fractures
• Displaced diaphyseal fractures
• Fractures in older animals
The use of non surgical management of fractures should always be considered for every fracture – in some
cases it will be the optimal fracture management option, however in many cases there are better options that
will return the animal to normal function more quickly.
FURTHER READING
Dyce J. Conservative management of fractures. BSAVA Manual of Small Animal Fracture Repair and Management.
Coughlan & Miller 1998.
55
Principi di artrodesi
56
S. Langley-Hobbs
Arthrodesis principles
Cambridge (UK)
ARTHRODESIS is the irreversible osseous fusion of a joint undertaken as a salvage procedure to restore
acceptable limb function. The aims of this talk and notes are to review the principles of arthrodesis.
ARTHRODESIS – THE INDICATIONS
Arthrodesis is used to treat joints having severe instability, severe osteoarthritis, or cancer. It is often referred
to as a salvage procedure, but if done correctly; arthrodesis can give a good to excellent functional outcome.
Essentially any diarthrodial joint can be arthrodesed, but the carpus, tarsus, digits and shoulder have the
best outcome. Carpal arthrodesis provides the best functional outcome. Elbow, stifle and hip arthrodesis generally have a poor to fair functional outcome, but joint pain may be substantially reduced.
ARTHRODESIS – THE BASIC PRINCIPLES
Arthrodesis is much more complicated that repairing a fracture. The surgical goal is similar- bony fusion - but
with arthrodesis, the implant system must counteract extensive bending forces. The implant system is being
placed across a joint that is designed to have motion – a highly negative factor for implant survivability and
bone healing. There are 4 fundamental principles that must be respected to have a successful arthrodesis:
• adequate cartilage debridement,
• proper bone alignment,
• rigid stability and compression
• bone graft augmentation.
Practical tips that can be used to address each principle are described below.
Principle 1: Articular cartilage debridement – The articular cartilage must be removed from the ends of
the bone over the majority of the weightbearing surfaces. Cartilage that is left behind increases the chance
of inadequate bony fusion between the two bones. The cartilage can be removed using a curette, motorized
burr or by performing a juxta-articular osteotomy. A hand curette will adequately remove cartilage when using a scooping or scraping action. When using a curette, an attempt should be made to invade the subchondral bone plate, ensuring access to a source of mesenchymal stem cells and vascular invasion. If the
bone ends are sclerotic, a motorized burr may be superior to a hand curette. A motorized burr removes articular cartilage much more quickly than a hand curette, but generates extraordinary heat. Copious lavage
should be used when using a motorized burr to reduce the risk of thermal necrosis. Necrotic bone cells will
need to be removed and replaced, increasing the time to reach bony union. The burr should be used to remove articular cartilage and superficial bone. Some bleeding of bone is desirable, but over-aggressive bone
removal may make alignment of the joint more difficult and reduce stability of the articulation to be
arthrodesed. After removal of articular cartilage the joint should be copiously flushed to remove cartilage debris. Small holes can be drilled in the ends of the bone articulations using a k-wire or small drill bit. This is
often referred to as forage or osteostixis and enhances neovascularization and provides a source for mesenchymal stem cells. Another method that can be used to prepare the bone surfaces is a juxta-articular osteotomy of the ends of each bone. Copious lavage should be used during the cutting process to avoid thermal necrosis. The line of the osteotomy should be planned carefully to achieve the proper joint angle after
the stabilization. This procedure may also cause shortening and this should be taken into account when determining what angle to fuse the joint at.
Principle 2: Bone alignment – A good functional outcome following arthrodesis requires adequate alignment of the limb. Care should be taken to ensure proper axial and rotational alignment. Malalignment leads
to gait abnormalities, reduced willingness to use the limb and abnormal forces placed across adjacent joints,
which may predispose them to osteoarthritis or instability. The arthrodesis should be positioned at a functional angle. A proper functional angle is best chosen by measuring the opposite normal joint using a goniometer. This is best performed while the patient is in a standing position. Alternatively, the angle can be
selected from known joint angles from various surgical text and journal articles.
Principle 3: Stabilization and implant system – Rigid stability is a must. The implant system must be able
to withstand tremendous bending and distractive forces for a prolonged period of time. The most commonly
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used implant systems for arthrodesis are bone plates, plate-rod constructs, pin and tension bands, and external fixators. Cross pins or lag screws can be used alone to achieve arthrodesis, but these methods are less
secure and should only be used in very young, small patients. Once the joint is properly aligned one or two
appropriately sized pins can be placed across the ends of the bones to provide temporary stabilization while
the primary implant system is applied. The pins can be removed after applying a bone plate, or if desired
the pins can be left in place if they were initially placed such that they do not interfere with the bone plate
or plate screws. If the pins are left in place, a plate-rod construct has been created. The advantage of leaving the pins in place is the ability for them to absorb some of the load, reducing plate strain and risk of failure. Compression should be placed across the site of arthrodesis to give improved stability. Greater stability reduces the chance of implant cycling and failure and enhances bone healing. Bone plates should ideally
be placed on the tension surface of the bones to reduce the chance of implant failure. Unfortunately this is
not always possible due to poor access due to overlying soft tissues and the lack of a true contiguous tension surface along the course of the conjoined bones. If a bone plate is applied to the compressive surface of
the bones, the implant should be sized accordingly to handle the additional load. Addition of adjunctive implants such as pins or an external fixator to share loads can help protect the plate and screws. External fixators can also be used effectively as the sole means of stabilization for arthrodesis. They are particularly useful in patients having open wounds over the joints that require arthrodesis. Following bony union, the external fixator is easily removed. In contrast, the use of internal fixation in these patients predisposes them to
infection. If infection occurs, the bone plate, screw and any pins may have to be surgically removed to resolve the infection. Arthrodesis techniques have been described in detail in multiple surgical texts and a
through discussion for each joint is beyond the scope of these notes and presentation.
Principle 4: Bone augmentation – Autogenous bone grafts are easy and quick to harvest and speed bony
union of the arthrodesis. Bone grafts can be harvested typically in 10-15 minutes. Autogenous cancellous
bone grafts have osteoconductive, osteoproductive and osteogenic properties. The most productive harvest
sites are the greater tubercle of the humerus and the ilial wing. Other sites that can be used include the proximal tibia, the proximal femur and the sternum, but these sites are not recommended unless the shoulder
and ilium are not available for some reason (usually because of poor presurgical planning!) Bone graft is
harvested from the humerus by drilling a hole with a large pin and harvesting cancellous bone using a
curette. The same technique can be used for the ilial wing; however an alternative technique that provides
a large volume of corticocancellous graft makes use of the acetabular reamer. The reamer is used to harvest
bone form the lateral cortex and medulla of the ilial wing. Following graft harvest from either site, the collected bone is stored in a syringe, stainless steel bowl or on a blood-soaked gauze (do not accidentally discard the gauze!). If possible the graft should be harvested immediately prior to placing it at the site of
arthrodesis to increase viability of osteoblasts, growth factors and the bone scaffold, however it is often more
convenient to harvest the graft at the beginning of surgery particularly in situations when a tourniquet is
used for the limb that is being arthrodesed. Other products available “off the shelf” for use to enhance bone
production, including various synthetic bone substitute compounds, lyophilized and frozen bone products.
REFERENCES AND FURTHER READING
Dyce J Arthrodesis in the dog. In Practice 1996 18, 267-279.
58
Stefan Lohmander
MD, PhD, Lund (S)
STATE OF THE ART LECTURE
L’esito delle lesioni traumatiche
del ginocchio. Cosa sappiamo oggi?
59
The injured joint and post-traumatic osteoarthritis What happens, what can we do for our patients?
Stefan Lohmander, MD, PhD, Professor
Department of Orthopaedics, Clinical Sciences Lund, Lund University, Sweden - [email protected]
Osteoarthritis (OA) is a multifactorial condition with genetic and environmental determinants. All cases are
influenced by both genetics and environment, with the distribution and weight of causes forming a continuum between the extremes of predominantly genetic or predominantly environmental. For example, the risk
of post-traumatic OA after a meniscal injury of the knee is influenced by a familial history of OA, by the
presence of nodal OA of the hand (a marker of ‘generalized’ OA), by obesity, and by sex. The expression
of OA in any individual (the presence or absence of inflammation, pain, cartilage loss, bone formation, etc.)
may further be determined by the particular mix of genetic and environmental influences in that individual1.
OA in which previous joint injury is identified as an important cause is common, especially in the young
and middle-aged persons. By 10-20 years after the rupture of a cruciate ligament or meniscus of the human
knee, about half of those injured will show radiographic signs of OA, and many will have significant symptoms already when aged between 30 and 502-6. This represents an important clinical treatment challenge in
that there is no high-level evidence that surgical resection or reconstruction of the torn meniscus or cruciate
ligament will benefit the short-term outcome or decrease the risk of OA development, as compared to nonsurgical management7-13.
The young active person with a knee injury leading to later OA may appear straightforward to identify as
post-traumatic OA, but the contribution of additional risk factors for OA development such as family history, hand OA, and obesity must be taken into account and should form part of patient counseling2, 14. The
seemingly straightforward case definition of post-trauma OA is further muddled by the common presence
in middle-aged persons of meniscus lesions (incidental or elicited by minor sprains) associated with an increased risk of knee OA development15-16. Completing the continuum, lesions of the menisci and cruciate ligament are frequent in OA knees, even in the absence of a clear history of injury17-18.
From the basic research perspective, OA following joint injury offers unique opportunities for studying and intervening in the earlier phases of human and animal OA development. In parallel, joint injury in the animal is
an important pre-clinical model for OA commonly used in the pharmaceutical industry in the development of
new treatments for OA19. We stand to gain much from a better understanding of post-traumatic OA.
REFERENCES
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Dieppe PD, Lohmander LS. Pathogenesis and management of pain in osteoarthritis. Lancet 2005;365:965-73.
Lohmander LS, Englund M, Dahl, LL, Roos EM. The Long-term Consequence of Anterior Cruciate Ligament and
Meniscus Injuries: Osteoarthritis. Am J Sports Med 2007;35:1756-69.
Lohmander LS, Östenberg A, Englund M, Roos H. High prevalence of knee osteoarthritis, pain, and functional
limitations in female soccer players twelve years after anterior cruciate ligament injury. Arthritis Rheum 2004;
50:3145-52.
Roos HP, Laurén M, Adalberth T, Jonsson K, Roos E, Lohmander LS. Knee osteoarthritis after meniscectomy.
Prevalence of radiographic changes after twenty-one years, compared with matched controls. Arthritis Rheum
1998;41:687-93.
Roos E, Östenberg A, Roos H, Ekdahl C, Lohmander LS. Long-term outcome of meniscectomy – Symptoms, function, and performance tests in patients with or without radiographic osteoarthritis compared to matched controls.
Osteoarthritis Cartilage 2001;9:316-24.
Englund M, Roos EM, Lohmander LS. Impact of type of meniscal tear on radiographic and symptomatic knee osteoarthritis. A 16-year follow-up of meniscectomy with matched controls. Arthritis Rheum 2003;48:2178-87.
Linko E, Harilainen A, Malmivaara A, Seitsalo S. Surgical versus conservative interventions for anterior cruciate
ligament ruptures in adults. Cochrane Database Syst Rev 2005:CD001356.
Spindler KP, Wright RW. Clinical practice. Anterior cruciate ligament tear. N Engl J Med 2008;359:2135-42.
Spindler KP, Kuhn JE, Freedman KB, Matthews CE, Dittus RS, Harrell FE, Jr. Anterior cruciate ligament reconstruction autograft choice: bone-tendon-bone versus hamstring: does it really matter? A systematic review. Am J
Sports Med 2004;32:1986-95.
Meuffels DE, Favejee MM, Vissers MM, Heijboer MP, Reijman M, Verhaar JA. Ten year follow-up study comparing conservative versus operative treatment of anterior cruciate ligament ruptures. A matched-pair analysis of
high level athletes. Br J Sports Med 2009;43:347-51.
60
11.
12.
13.
14.
15.
16.
17.
18.
19.
Moksnes H, Risberg MA. Performance-based functional evaluation of non-operative and operative treatment after
anterior cruciate ligament injury. Scand J Med Sci Sports 2009;19:345-55.
Biau DJ, Tournoux C, Katsahian S, Schranz PJ, Nizard RS. Bone-patellar tendon-bone autografts versus hamstring
autografts for reconstruction of anterior cruciate ligament: meta-analysis. BMJ 2006;332:995-1001.
Frobell RB, Roos EM, Roos HP, Ranstam J, Lohmander LS. A randomized trial of treatment for acute anterior
cruciate ligament tear. New Engl J Med 2010;in press.
Englund M, Paradowski P, Lohmander LS. Association of radiographic hand osteoarthritis with radiographic knee
osteoarthritis after meniscectomy. Arthritis Rheum 2004;50:469-75.
Englund M, Guermazi A, Lohmander LS. The role of the meniscus in knee osteoarthritis, a cause or consequence?
Radiologic Clinics North America 2009;47:703-12.
Englund M, Guermazi A, Lohmander LS. The meniscus in knee Osteoarthritis. Rheum Dis Clin North Am
2009;35:579-90.
Englund M, Guermazi A, Roemer FW, Aliabadi P, Yang M, Lewis CE, Torner J, Nevitt MC, Sack B, Felson DT.
Meniscal tear in knees without surgery and the development of radiographic osteoarthritis among middle-aged and
elderly persons: The Multicenter Osteoarthritis Study. Arthritis Rheum 2009;60:831-9.
Englund M, Guermazi A, Gale D, Hunter DJ, Aliabadi P, Clancy M, Felson DT. Incidental meniscal findings on
knee MRI in middle-aged and elderly persons. N Engl J Med 2008;359:1108-15.
Wollheim FA, Lohmander LS. Pathology and animal models of osteoarthritis. In Sharma L, Berenbaum F. Osteoarthritis. Philadelphia, Mosby Elsevier 2007, pp. 104-12.
61
Antonio Pozzi
DMV, MS, Dipl ACVS, Florida (USA)
Come migliorare
la visualizzazione del menisco
62
How to improve meniscal visualization
Antonio Pozzi, DMV, MS, Dipl ACVS
Florida (USA)
Meniscal injury in the dog is most commonly associated with ligament injury of the stifle joint. The reported incidence varies from 50 to 90%. Damage to the menisci can be either acute or degenerative and usually involves the caudal and medial portions of the medial meniscus. The medial meniscus is firmly attached
to the tibia by the medial collateral ligament, the synovium, and the meniscal ligaments. As a result, during
drawer movement and weight bearing the caudal pole may become entrapped between the femoral and the
tibial condyle and therefore may tear due to the shear stress applied on the longitudinal and radial fibers.
MENISCAL EXAMINATION
Exposure
The first step in meniscal examination is adequate exposure to allow evaluation of its gross appearance. Exposure should be optimized using retractors and distraction with or without the aid of distraction devices.
Both valgus and varus stress are required to allow visualization and probing of both menisci. Utilizing a
craniomedial or craniolateral arthrotomy, or arthroscopy from cranial portals, visualization of the medial
meniscus is improved by applying external rotation and valgus stress to the limb; application of varus stress
and internal rotation aids in exposing the lateral meniscus. In stable stifles with a partial CrCL rupture the
caudal pole of the medial meniscus may not be visualized with a cranio-medial arthrotomy, however it can
be well visualized arthroscopically. In case the caudal pole cannot be evaluated, the surgeon can elect to perform an arthroscopic examination of the medial meniscus with or without debridement of the CrCL, debride the torn CrCL via a craniomedial or craniolateral arthrotomy, or perform a caudo-medial approach
to the stifle. Similarly a caudal medial arthroscopy port can be used if necessary (for diagnosis and treatment). It should be emphasized that the caudal pole of the medial meniscus is the most common site of injury, thus it should be evaluated carefully for the presence of tears in every case. The flexion angle of the
joint while examining the meniscus is important: visualization is best obtained in approximately 110°-130°
of limb extension, but this angle may vary depending on the morphology of the dog. The position of the
arthroscopy portals is important for diagnostic arthroscopy of meniscal pathology. A common mistake is to
place the arthroscopy portals too far laterally or medially over the femoral condyles, where instrument passage damages the femoral articular cartilage. The safe area for instrument passage is with the portal just medial and lateral to the patellar tendon with passage into the femoral notch region. The portals should also
be selected based on the dog morphology. Dogs with steeper tibial plateau angle require a more proximal
arthroscopy port, placed in a sub-patellar position. A good rule of thumb is that the arthroscopy portals
should be located approximately where the tibial plateau axis intersects the patellar tendon in the lateral radiographic image. Inspection of the menisci is one of the most difficult arthroscopic procedures performed
in the stifle. Careful attention to the placement of the arthroscopic portals, the arthroscope, the orientation
of the light post, the position and angulation of the limb, and appropriate debridement of the fat pad as necessary are required for optimal visualization of the menisci.
Meniscal evaluation (observation)
First the position of the meniscus is assessed. A portion or the entire caudal horn of the medial meniscus
may be folded cranially, suggesting a displaced bucket handle tear, a flap or a peripheral detachment type of
vertical longitudinal tear. The meniscus may be in its normal position and may look normal. However, careful probing should be performed to rule out incomplete vertical longitudinal tear, or an abaxial tear behind
the femoral condyle. At this stage it is also useful to elicit cranial tibial subluxation to evaluate meniscal stability. By causing the tibia to subluxate cranially, peripheral detachment and bucket handle tears may displace cranial to the femoral condyle as the tibia translates cranially.
Meniscal evaluation (probing)
After inspection of the axial rim and the femoral surface of the meniscus, probing should be performed to
evaluate regions that cannot be observed. The use of a probe to palpate the meniscus increases the sensitivity for diagnosing meniscal pathology during both arthrotomy and arthroscopy. Palpation with the probe
should be performed to assess the integrity of both femoral and tibial surfaces as well as the meniscal attachments. Irregularities on the surface and hooking or catching of the probe suggest an incomplete vertical
longitudinal tear. Hooking of the probe at the periphery of the meniscus should be interpreted carefully be63
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cause the edge of the caudal pole is only loosely attached to the joint capsule through the coronal ligament.
The probe is also used to evaluate the texture of the meniscus. A normal meniscus is firm and resilient, but
not hard; a soft meniscus is likely degenerative or may have a horizontal cleavage tear. In some cases partial horizontal clefts in the rim may be difficult to diagnose. If a horizontal cleft is suspected based on the
texture of the meniscus, a partial meniscectomy is recommended to allow better probing of the rest of the
tear. Only evaluation of the whole meniscus can indicate the extent of meniscectomy required to resect
pathologic tissue. After diagnosing a bucket handle tear, it is imperative to evaluate the remainder of the
meniscus since multiple tears can be present, and the additional tears can be easily missed. It might be preferable to first perform a partial meniscecomy, then probe the remaining meniscal tissue. A conservative partial meniscectomy followed by probing may facilitate exposure and the remaining meniscus can be more
thoroughly evaluated.
Arthroscopic examination of the meniscus with accurate probing is the best method for diagnosing meniscal pathology in dogs. The magnification and illumination provided during arthroscopy allows close evaluation of the menisci. However, a thorough meniscal evaluation is mandatory for arthrotomy as well. A
meniscal tear missed at the time of joint exploration may cause persistent lameness if left untreated. Probing
the meniscus increases the sensitivity of arthrotomy by 2-3 folds.
Initial assessment of the position of the meniscus is critical. A portion or the entire caudal pole of the medial meniscus may be folded cranially, suggesting a displaced bucket handle, a flap or a peripheral detachment
tear. Complex tears may present as a folded caudal pole. In these cases probing is critical to evaluate if the
meniscus can be salvaged with a partial meniscectomy or should be removed. Exposure should be optimized
using retractors, stifle distractor and flexion or extension of the joint. Applying varus or valgus stress is also useful for opening the lateral or medial stifle compartments. In stable stifles with a partial CCL rupture
the caudal pole of the meniscus may not be visualized with a cranio-medial arthrotomy. In these cases the
surgeon should debride the CCL or perform a caudo-medial approach to the stifle. It should be emphasized
that the caudal pole of the medial meniscus is the most common site of injury, thus should be evaluated carefully for the presence of tears. After visualization of the axial rim, probing should be performed to assess the
integrity of both femoral and tibial surfaces and the meniscal attachments. Irregularities on the surface and
hooking of the probe suggest an incomplete or non-displaced bucket handle tear. Hooking of the probe at
the periphery of the meniscus may suggest a peripheral detachment, but should be interpreted carefully because the edge of the caudal pole is only loosely attached to the joint capsule. After diagnosing a bucket handle tear, the rest of the meniscus should be evaluated for multiple tears that can be easily missed. This is an
important step when performing a partial meniscectomy. Late meniscal injuries after TPLO may originate
from meniscal tears that were missed at the first evaluation.
REFERENCES
1.
2.
3.
4.
5.
Mahn MM, Cook JL, Cook CR, et al: Arthroscopic verification of ultrasonographic diagnosis of meniscal pathology in dogs. Vet Surg 34:318-323, 2005.
Samii VF, Dyce J: Computed tomographic arthrography of the normal canine stifle. Vet Radiol Ultrasound 45:402406, 2004.
Thieman KM, Tomlinson JL, Fox DB, et al: Effect of meniscal release on rate of subsequent meniscal tears and
owner-assessed outcome in dogs with cruciate disease treated with tibial plateau leveling osteotomy. Vet Surg
35:705-710, 2006.
Ralphs SC, Whitney WO: Arthroscopic evaluation of menisci in dogs with cranial cruciate ligament injuries: 100
cases (1999-2000). J Am Vet Med Assoc 221:1601-1604, 2002.
Pozzi A, Hildreth B, Rajala-Shultz P: Comparison of arthroscopy and arthrotomy for the diagnosis of medial meniscal pathology: An ex vivo study. Vet Surg 37(6):23-32, 2008.
64
Antonio Pozzi
Perle e trabocchetti nelle osteotomie
tibiali (TPLO, TTA, CWTO)
65
Pearls and pitfalls of tibial osteotomy techniques
Florida (USA)
TIBIAL PLATEAU LEVELING OSTEOTOMY (TPLO)
A. Methodical planning for accurate position of osteotomy
The TPLO is a radial corrective osteotomy of the proximal tibia. Because of its unique location, TPLO isolates a small metaphyseal fragment caudally, and the tibial tuberosity cranially. The consequences of an osteotomy placed too cranially can be an increased risk of tibial tuberosity avulsion fracture, or patellar tendon transection. An osteotomy placed too caudally and proximally, although may be geometrically correct
in some cases (centered on tibial eminence), may complicate proximal plate fixation and increase the risk of
mechanical failure of the TPLO (rockback). Accurate pre- and intra-operative planning is necessary to prevent these complications. In most cases the following guidelines can be followed:
1. The tibial tuberosity area isolated by TPLO should have a trapezoidal shape, where the distal aspect of
the tibial tuberosity adjacent to the osteotomy should always be wider than the proximal aspect. A “reverse” trapezoid should be avoided;
2. The width of the metaphyseal fragment should correspond to about 2/3 of the total width, while the
width of the tuberosity should be about 1/3 of the total width;
3. The osteotomy should exit the caudal cortex with an angle of about 90 degrees;
4. The proximal fragment should have enough room for placing the plate screws at least 1 screw diameter
from the osteotomy and the joint line;
5. Template the osteotomy before surgery. Choose the appropriate saw radius and placement of the osteotomy. The osteotomy should be centered on the intercondylar eminences and isolate a broad-based
tibial crest segment. Measure the distance from the tibial tuberosity to the intersection of the osteotomy
with the tibial profile cranial to the plateau, and archive this for application in surgery.
B. Under or overcorrection of TPA
One of the advantages of TPLO is its ability to modify the TPA with accuracy. However, its precision depends on the accurate placement of the osteotomy and precise rotation of the fragment. A distally centered
osteotomy will cause undercorrection of the TPA caused by tibial axis shift. In addition, mistakes during
placement of the marks may cause under or overcorrection of TPA. Incomplete rotation of the TPLO fragment can be another cause for undercorrection of the TPA. Causes of difficult rotation of the fragment include poor placement of the TPLO jig (proximal pin) or of the osteotomy (relative to the jig) and tibiofibular synostosis. For example, in giant breed dogs a relative small diameter radial osteotomy can be difficult
to rotate because of a proximal position. Similarly, a jig pin distally placed may not allow a smooth rotation
of the fragment, because of the distance between center of osteotomy and proximal jig pin. Severe periarticular fibrosis can also cause frustration during rotation of the TPLO fragment. Strategies to prevent under-rotation of the fragment include removing the jig to allow rotation of the fragment, or performing a fibular osteotomy or a disarticultion between fibula and tibia in cases of synostosis between the tibia and fibula. Overcorrection is less likely, and usually prevented by accurate placement of the rotation marks.
C. Tibial deformity and rotational instability
When developing the original TPLO surgical technique, Slocum emphasized the importance of correcting
femoral and tibial deformities because of the increased risk of complications in case of limb deformity. Although this area needs more research, TPLO seems to function well only if rotational instability at the joint
is minimal. Dogs with varus-valgus deformities (femur, tibia), torsional deformities or medial patellar luxation may have greater rotational instability than dogs without deformities. The following pearls are important to anticipate and prevent complications related to this issue:
1. If required, angular correction to address tibial varus/valgus and torsional deformity is readily achieved
by specific manipulations of the TPLO jig pins. Because of the complexity of the stifle biomechanics,
small changes in relative alignment of the femoro-tibial articular surfaces can cause rotational and translational instability e.g. pivot shift. At each step of the surgery, limb alignment in both flexion and extension should be evaluated. It is important to evaluate alignment in both flexion and extension because
femorotibial alignment can change over a full range of motion.
2. Identify pre-existing medial patellar luxation (MPL). Note that internal rotational instability of the stifle
is associated with CCL rupture and this cannot be neutralized by standard TPLO. An undiagnosed low66
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grade MPL associated with CCL rupture can be worsened by TPLO and cause persistent lameness. Distal femoral varus and internal torsion of the proximal tibia are not uncommon findings in retrievers and
bull terrier types with MPL and CCL rupture. Lateralization of the tibial tuberosity can be achieved by
torsional correction using the jig, but this will produce distraction of the medial osteotomy gap that
should be packed with an autogenous bone graft. It can also be achieved by translation of the metaphyseal fragment medially. Consider laterally-based closing wedge ostectomy of the distal femur, to realign
the quadriceps mechanism, if varus exceeds 15o. Lateral imbrication is invariably performed to address
MPL and implies exploratory arthrotomy should be lateral and not medial. Additional procedures e.g.
trochlear sulcoplasty are performed on an as-needed basis. In those cases with patella alta as a predisposing factor for MPL, Slocum-style TPLO may be inferior to cranial closing wedge ostectomy, which will
relocate the patella more distally in the trochlear sulcus.
D. Position of the plate
The advent of locking TPLO plates has improved the technique and the ability to achieve a stable fixation.
However, locking plates are not without risk of failure if placed inappropriately. The ideal placement of the
proximal half of the locking plate should be in the center of the metaphyseal fragment. Plates applied too
close to the osteotomy may be at risk of screw-bone interface failure. A plate too proximal may increase the
risk of intra-articular screws. The newly designed TPLO plates are pre-contoured and the direction of the
holes helps with avoiding placing screws in the joint. However, changes in contouring of the plate, or poor
placement of the locking screws (not in the axis of the screw hole) can cause intra-articular placement of
screws. Maintain the TPLO plate parallel to the tibial long axis. The distal end of the TPLO plate tends to
tilt cranially during placement, resulting in poor seating of the distal screw. Because of the shape of the tibia, the screws should be placed in the caudal half of the metaphysis, where the tibial diameter is greater. Cranially placed screws are shorter and placed in thin cortical bone.
TTA
A. Position of plate
Poor contouring of the plate, or fixation of the plate to the most caudal surface of the diaphysis may cause
plate deformation and malalignment of the tibial tuberosity. Strategies to prevent include:
Strategies to prevent include:
1. Do not oversize the plate;
2. Evaluate the tibial tuberosity and crest conformation. In some cases the orientation of the crest relative
to the tibial diaphysis force the plate in a caudally tilted position before advancement. Tibial tuberosity
advancement causes severe shift of the distal plate holes. To prevent this problem the proximal end of
the plate can be “tilted” caudally, by drilling the proximal holes 1-2 mm more caudal than the distal fork
hole (relative to the cranial margin of the tibial tuberosity)
3. The position of the distal end of the osteotomy contributes to the tilting after advancement; a more proximal osteotomy will cause more displacement/titling of the distal end of the plate.
4. The fork should not be placed too cranial, purchasing more fascia than bone or too caudal (bone is
weaker).
5. Ensure the holes are oriented in parallel direction. Do NOT shift the jig during drilling or fork will not
engage properly.
B. Position of the osteotomy
Although the TTA osteotomy is significantly easier than TPLO, mistakes in positioning the osteotomy can
predispose to complications. Preoperative planning is recommended to plan the proximal extent of the osteotomy. These are pearls that the surgeon should consider preoperatively and intraoperatively:
1. The width of the tibial tuberosity fragment should be about 1/3 of the total width of the proximal tibia;
2. Landmarks for the proximal extent of the osteotomy are Gerdy tubercle, region cranial to intermeniscal
ligament;
3. The distal aspect of osteotomy determines the amount of tilting of the plate distally. See above;
4. Straight osteotomy is preferred, but a gentle distal curve may be necessary in some cases.
C. Safe zones and use of marks
It is useful to define the “safe zones” with a cautery mark. The following are marks that can be useful:
1. Tibial tuberosity for proximal hole for fork;
2. Proximal mark of osteotomy to avoid menisci and fork holes;
3. Distal mark to check safe distance from plate holes;
4. Width of osteotomy (relative to the whole proximal tibia).
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CWTO
A. Preoperative planning, size and location of CWTO
Planning is crucial to achieve consistent results with CWTO. Several studies have shown that a more distal
osteotomy requires a bigger wedge to decrease the TPA to about 5 degrees. It has been also suggested that
alignment of the cranial cortices may decrease the tibial axis shift. The following pearls may help achieving
more consistent results:
1. Use a sterilized template (i.e. from radiographic films) or a trigonometric method;
2. Place the osteotomy as proximal as possible.
3. Use temporary or permanent fixation with a cranial cerclage wire;
4. When using a proximal CWTO with cortical alignment, a wedge equal to TPA allow correction of the
TPA to about 5 degrees.
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Antonio Pozzi
Lussazione mediale della rotula e
rottura del legamento crociato
nei cani di taglia piccola e grande
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A. Pozzi
Managing MPL and CCL rupture in small and large
breed dogs
Florida (USA)
Medial patellar luxation has been attributed to many factors. Medial displacement of the quadriceps, a shallow femoral trochlear groove, and medial displacement of the tibial tuberosity all play a roll in the pathogenesis of medial patellar luxation. With medial luxation of the patella there are often distal femur or proximal tibial deformities. The origin of this deforming torsional force has not been clearly established. A large
potential for axial and torsional growth exists in the cartilage columns of the growth plates. Growth plates
yield to forces rapidly by either increasing or decreasing their rate of growth, whereas mature bone responds
to changes in forces through bone deposition or resorption. Therefore, remodeling of mature bone is much
slower. This is not present in all dogs with medial patellar luxation.
Chronic rotational instability caused by the MPL can predispose to CCL rupture. Therefore, the combination of these stifle pathologies is not uncommon, and should be suspected in any clinical case with acute onset of lameness, moderate to severe pain and effusion.
Several treatments have been reported for MPL. Additionally a large number of surgical techniques for stabilization of the CCL-deficient stifle are commonly used. Therefore, there are many possible combinations
of techniques for the MPL/CrCL-deficient dog. The treatment of MPL combined with CCL rupture aims
at the same goals of the surgical treatments of the isolated MPL and CCL rupture:
1. To resolve the dog’s clinical signs (lameness, pain);
2. To reestablish a normal patellar tracking and minimize development of osteoarthritis;
3. To reestablish normal joint motion and joint stability (cranio-caudal and external-internal rotation) as
combined MPL and CCL rupture significantly alter joint motion.
The principles of MPL correction apply to all clinical cases of CCL insufficiency and MPL. All dogs should
be thoroughly evaluated with an orthopedic and radiographic exam. Orthogonal views of the femur and tibia are recommended. The cranial-caudal view of the femur is useful to rule out a varus deformity of the femur. CT scan may provide more information if a deformity is suspected.
The selection of the surgical technique depends on the size of the dog, the presence of femoral or tibial deformities and the grade of the MPL. The combination of extra-capsular circumfabellar lateral suture
(LS)/lateral imbrication with trocheoplasty is commonly used in small dogs. This combination is indicated
in small dogs that had a low grade subclinical MPL (grade 1-2) progressing to grade 3 after CCL rupture.
The CCL deficiency causes internal tibial rotation, which exacerbates MPL. Reducing the internal tibial rotation using LS may be sufficient to realign the quadriceps mechanism. Additionally, a trocheoplasty may
improve patello-femoral joint congruity.
The dog should be preoperatively evaluated by palpation of the stifle. If external rotation of the tibial
tuberosity allows reduction of the patella and continuous normal patellar tracking, LS without tibial tuberosity is indicated. In some cases a tibial tuberosity transposition is indicated to realign the quadriceps mechanism. Correction of rotational deformity of the tibia should be done in young animals with remodeling potential. In older animals the entire limb has developed abnormally, with permanent bone and ligaments’ abnormalities. Simply rotating the tibia medially or laterally does not correct these problems.
The use of LS as anti-rotational suture is less likely to be successful in large breed dogs. Most large dogs
with MPL have a distal femoral deformity, which may require correction. There are no clear guidelines, but
most surgeons perform correction in case of a distal femoral varus angle >11-13°. My clinical experience is
that large dogs may be at higher risk of recurrence of MPL than small dogs if varus is not corrected. The
femoral correction can be combined with tibial osteotomies such as TPLO, TTA and cranial closing wedge
osteotomy (CTWO). The advantage of TTA is that a moderate tibial tuberosity transposition can be performed without additional procedures. However, successful treatment of CCL rupture and MPL can be
achieved also with CTWO and TPLO.
Femoral corrective osteotomies are rarely indicated in small dogs. Because of the small size of the femur, and
frequent condrodystrophic conformation, this procedure is complex and may have higher risk of complications. Small dogs with grade 4 lesions may benefit of femoral osteotomies, while most cases with 10-15°
varus angle can usually cope with the deformity, with no need of corrections.
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Antonio Pozzi
Trucchi e trabocchetti nelle tecniche
di stabilizzazione extracapsulare
del ginocchio
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Pearls and pitfalls of extracapsular techniques
Florida (USA)
The goal of the treatment of cranial cruciate ligament (CCL) insufficiency is to provide good quality of life
to the patient, while improving limb function. Several surgical techniques have been described including intra-articular stabilization, extra-articular stabilization, and tibial osteotomy techniques. Extra-articular stabilization techniques are predicated on transiently restraining abnormal stifle motion until sufficient joint adaptation provides dynamic joint stability. Postoperative complications after CCL repair surgery have a negative impact on patient’s quality of life and clients’ satisfaction. This lecture will discuss how to prevent some
complications associated with extracapsular techniques.
LATENT MENISCAL TEARS
Accurate joint exploration and meniscal evaluation are crucial steps of the surgical treatment of the CCL deficient stifle. Meniscal injury secondary to CCL insufficiency occurs in 40-70% of cases. Surgeons that routinely diagnose less than 10-20% of meniscal tears are likely missing some tears. The medial meniscus may
be exposed by arthrotomy through a cranio-lateral, cranio-medial stifle approach or a caudo-medial approach
to the medial compartment of the stifle. The exposure of the medial meniscus is easier through a cranio-medial approach, but some surgeons prefer to use a cranio-lateral arthrotomy during extracapsular techniques.
The caudo-medial approach to the stifle is used when there is a stable joint and the medial caudal pole of the
meniscus is not visualized easily. To expose the meniscus the following steps are recommended:
1. Perform a precise arthrotomy (3-5 mm on the side of the patellar tendon); appropriate length for miniarthrotomy or full arthrotomy;
2. Proximal-distal retraction of the fat pad using a Rake or a Volkman retractor;
3. Debridement of the CCL (if not functional);
4. Placement of Gelpi retractor (hooked to medial and lateral aspect of the joint);
5. Placement of Hohman or stifle distractor;
6. Evaluation of meniscus at DIFFERENT FLEXION ANGLES and after applying VALGUS and VARUS
stress;
7. PROBING every region of the meniscus (especially the tibial surface and the caudal pole).
8. EVALUATION OF COLOR, CONSISTENCY, EDGES, SURFACE.
Arthroscopy is considered the first choice for meniscal diagnosis for its high sensitity and specificity if available. Arthroscopic-assisted arthrotomy can be another excellent method with the advantages of arthroscopy,
through a larger and easier approach.
NON-ISOMETRIC PLACEMENT OF THE TUNNELS
(LATERAL SUTURE, ANCHOR TECHNIQUE, TIGHTROPE)
This is one of the most common technical mistakes. Non-isometric placement of the extra articular prosthesis may cause early failure of the suture, decreased range of motion, early laxity. For the tibia it is recommended to place the tunnel in the cranial aspect of the extensor groove, or immediately behind it, as proximal as possible. A common mistake is to slide the drill bit too distal. It is useful to place an instrument (Mosquito) just proximal to the groove in the joint, to precisely position the tunnel. If a more traditional placement is used, the surgeon should drill the tunnel proximal and caudal to the tuberosity. Any location distal
to the tibial tuberosity is too distal. It is also crucial to evaluate the proximal tibial anatomy of each dog on
pre-operative radiographs. For example some dogs can have a very distal tuberosity, which might predispose
to a distal non-isometric tibial tunnel.
EARLY FAILURE OF THE ANCHORAGE OF THE PROSTHETIC SUTURE
This complication is usually caused by poor placement of the prosthetic suture. For example, the circumfabellar suture may fail because the suture was not passed behind the fabella or because multiple attempts using a cutting needle may have damage the femoro-fabellar ligament. The needle may be deviated from hitting the femur, or the fabella, and the suture may be placed caudally to the fabella, around the gastrocnemius muscle. To avoid this problem it is important to choose the insertion point of the needle based on its
radius of curvature. Most of the time the needle is inserted too close to the fabella. Other strategies include
passing the suture through a tunnel in the fabella. It is useful to perform some cadaver dissection to under72
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stand the best direction of the needle. Another cause of failure of the circumfabella suture is poor placement
due to severe fibrosis in case of chronic DJD or in case of fabella fractures or bipartite fabella. In these cases an anchor technique, ot the Tightrope may be indicated.
The femoral anchor or tunnel (Tightrope) is at risk of failure if not placed accurately in bone. The most frequent mistake is to place anchors or tunnels into the femoro-fabellar joint. Exposure of the femoro-fabellar
joint through a 5-10 mm approach allows precise placement.
EXCESSIVE TENSION OF THE PROSTHETIC SUTURE
The belief that a successful extracapsular technique should be “rock-solid” is a misnomer. For example, neutralization of the cranial drawer utilizing non-isometric points can impair range of motion and cause early
failure of the suture. Excessive tension of the suture causes increased lateral compartmental pressure and
may predispose to lateral meniscal injury and early OA. The small dogs are at higher risk of complications
after an excessively tight lateral suture because they are not able to compensate with their total joint reaction force for an unbalanced compartmental pressure. The tension of the suture should be selected based on
neutralization or decrease of the drawer to about 2-3 mm, while preserving normal range of motion. It is also crucial to check tibial rotation when choosing the tension. The tibia should not be externally rotated after extracapsular suture. The suture tension should allow 5-10 degrees of internal tibial rotation. In general
excessive tension is less concerning in case of large dogs weight-bearing soon after surgery, and in case of
nylon prosthesis for its decreased stiffness over time.
EARLY LAXITY
We already discussed some causes of early laxity. Another frequent cause of instability in the early postoperative period is poor compliance and excessive activity. No good solutions for non-compliant owners are
available, but postoperative rehabilitation has improved significantly the outcome and the postoperative
management in my experience. In case of the Tightrope, early laxity may be caused by: 1) soft tissue entrapment between the buttons and the bone; 2) poor placement of the tunnels; 3) infection and resorption
at the tunnel exits 4) suture failure. It is crucial to elevate soft tissue and periosteum in the site of the tunnel
exit. The button should be flat against the bone after tying the knot.
PERONEAL NERVE INJURY
This is a rare but severe complication of the circumfabellar suture technique. The most common cause is
excessive dissection caudal to the fabella. It is important to guide the dissection based on the palpation of
the fabella. It is also useful to maintain the joint in flexion to allow the biceps fascia to be retracted more easily and expose the fabella with less dissection. The dissection should be carried only to allow exposure of
the lateral aspect of the fabella. Anything caudal to it should not be elevated, excised, dissected.
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Antonio Pozzi
Riduzione mini-invasiva
delle fratture
74
Introduction to minimally invasive plate osteosynthesis
Florida (USA)
Recent advancements in fracture healing have focused on minimally invasive fracture stabilization technique. Invasive open surgical approaches necessary for anatomic fracture reconstruction disrupt the fracture
hematoma as well as the regional extraosseous blood supply. This iatrogenic trauma can retard the rate of
new bone formation and devitalize bone fragments which potentially may have remained viable if the fracture site was not disturbed. An understanding of the benefits of preserving the fracture hematoma and local blood supply has led to the development of the principle of biological osteosynthesis as a technique for
fracture management. The principles of biological osteosynthesis were developed to maximize healing potential by balancing biology and mechanics in the treatment of fractured bones. These principles are based
on preserving blood supply by minimizing exposure and disruption of the fracture site.
A new method of bone plating has evolved which allows a plate to be applied through small incisions, made
remote to the fracture site. This technique conforms to the principles of biological osteosynthesis since the
fracture site is not exposed and only minimally disturbed. The technique has been termed minimally invasive percutaneous plate osteosynthesis (MIPO), and has also been referred to as percutaneous plating. Percutaneous plating involves the application of a bone plate, typically in a bridging fashion, without making
an extensive surgical approach to expose the fracture site. The bone segments are reduced using indirect reduction techniques. Small plate insertion incisions are made at each end of the fractured bone and an epiperiosteal tunnel is made connecting those incisions. The plate is inserted through one of the insertion incisions and tunneled along the periosteal surface of the bone, spanning the fracture site. Screws are applied at
the proximal and distal ends of the plate through the insertion incisions or if necessary, through additional
stab incisions. Screws are not placed in the holes located in the central portion of the plate, which is often
positioned over the fracture.
Appropriate case selection is crucial to the success of MIPO. As with any technique, not all fractures are
amenable to percutaneous plate stabilization. Although MIPO is most applicable to comminuted diaphyseal
or metaphyseal fractures which may not be amenable to anatomic reduction, the technique can be utilized
in some simple transverse fractures. Plates are typically applied in a bridging fashion to stabilize comminuted fractures dissipating strain over the comminuted segment. The environment of relative stability provided by bridge plating results in fracture healing by secondary bone healing.
Although the MIPO technique can be applied to proximal limb fractures, we have found that femoral and
humeral fractures are typically more challenging to reduce using indirect techniques than antebrachial and
crural fractures. Femoral and humeral fractures may be amenable to MIPO after using an intra-medullary
pin, femoral distractor or traction table to achieve reduction and alignment of the fracture. In human patients MIPO has been demonstrated to be a successful method of fracture osteosynthesis in both humeral
and femoral fractures. MIPO has been utilized commonly to stabilize comminuted tibial fractures in both
humans and dogs. In our experience MIPO is an excellent choice for radial and tibial fractures which can
be indirectly reduced using a temporary external skeletal fixator. MIPO is well suited for stabilizing diaphyseal long bone fractures as there is usually a sufficient length of bone proximal and distal to the fracture
to allow for adequate plate purchase.
Indirect reduction techniques are generally utilized when performing MIPO fracture stabilization. The fractured limb segment is aligned and original length is restored. The intermediate fracture fragments are left
undisturbed in the soft tissue envelope. Indirect reduction means that fragments are manipulated indirectly
by applying corrective force at a distance from the fracture, by distraction or other means, without exposing
the fracture. In biological terms, indirect reduction techniques confer an enormous advantage by minimizing the iatrogenic damage incurred during surgery. If correctly applied, it will add minimal iatrogenic damage to tissues already traumatized by the fracture.
The plate is inserted through one of the incisions, slid through the soft tissue tunnel along the surface of the
bone, over the fracture site, until the end of the plate is visualized in the second incision. If available fluoroscopy should be used to visualize that the plate is properly contoured and positioned on the bone. If necessary the plate can be removed and re-contoured. Precise contouring and positioning of the plate becomes
less critical if a locking plate is used. Once the plate is fitted to the bone, screws are placed. Reports of MIPO
in animals have been promising. Our experience of MIPO procedures has been favorable with rapid stabilization of the fracture site by bridging callus, progressing to complete union. In order to validate MIPO for
use in dogs and cats, objective clinical trials and outcome based case series will be necessary.
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REFERENCES
1.
2.
3.
4.
5.
6.
7.
Baumgaertel F, Buhl M, Rahn BA. Fracture healing in biological plate osteosynthesis. Injury 1998; 29 Suppl 3: C3-6.
Field JR, Tornkvist, H. Biological fracture fixation: A perspective. Vet Comp Orthop Traumatol 2001; 14: 169-78.
Borrelli J, Jr., Prickett W, Song E, Becker D, Ricci W. Extraosseous blood supply of the tibia and the effects of different plating techniques: A human cadaveric study. J Orthop Trauma 2002; 16: 691-5.
Perren SM. Evolution of the internal fixation of long bone fractures. The scientific basis of biological internal fixation: Choosing a new balance between stability and biology. J Bone Joint Surg Br 2002; 84: 1093-110.
Johnson AL, Smith CW, Schaeffer DJ. Fragment reconstruction and bone plate fixation versus bridging plate fixation for treating highly comminuted femoral fractures in dogs: 35 cases (1987-1997). J Am Vet Med Assoc 1998;
213: 1157-61.
Schmokel HG, Stein S, Radke H, Hurter K, Schawalder P. Treatment of tibial fractures with plates using minimally invasive percutaneous osteosynthesis in dogs and cats. J Small Anim Pract 2007; 48: 157-60.
Pozzi A, Hudson CC, Lewis DD. Minimally invasive plate osteosynthesis: Initial clinical experience in 16 cases.
Veterinary Orthopaedic Society; Big Sky, Montana; March 9-14, 2008.
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Rico Vannini
Dr Med Vet, Dipl ECVS, Regensdorf (CH)
La visita ortopedica Consigli e suggerimenti
per una diagnosi di successo
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R. Vannini
The orthopedic examination tips and tricks to a successful diagnosis
Rico Vannini, Dr Med Vet, Dipl ECVS
Regensdorf (CH)
A good orthopedic examination (OE) is the key for a successful diagnosis and treatment of a dog with a
chronic lameness. Well and systematically performed, the OE should allow us to rule out non-orthopedic
problems as a cause of lameness, to define the source of the lameness, to get a tentative clinical diagnosis
and to decide, which further diagnostic technique will be most useful to obtain a final diagnosis. Imaging
techniques such as radiographs, CT, MRT or arthroscopy should primarily confirm our clinical diagnosis
and not be used as a general searching tool. If we use it as such, there is a risk to detect and to treat abnormal findings, which are of no clinical importance.
A good OE starts with a detailed, careful history. This should include at least onset and duration of the lameness, possible cause of lameness (trauma), any previous orthopedic problems, course of the disease, type
lameness (intermittent, permanent, warm up effect etc), treatments and success of these.
The OE should always go through the same basic steps:
1. Observe the animal while it is moving, standing and sitting.
2. Palpate & manipulate the dog.
3. Perform specific examinations.
A systematic approach helps to avoid missing important pieces of information.
1. OBSERVE THE ANIMAL WHILE IT IS MOVING, STANDING AND SITTING
Analyze the gait and the type of lameness. Determine which leg the dog is limping on, the type and severity of lameness. This is often different to what the client told you. Have the dog walk, trot and gallop. Repeat if necessary on different grounds (lawn, asphalt, gravel). Look for signs of ataxia, toe dragging, gait abnormalities. A dog with painful joints will quickly shift from walk to gallop when going faster. Gallop allows
shorter strides and distribution of the weight on two legs at the same time. This is less painful than a trot.
Thus a dog that avoids to gallop but prefers to trot has very not likely an orthopedic, but a (neuro)muscular problem causing weakness. The trot is an energy saving gait, which is easier for these dogs than to gallop. Remember not all gait abnormalities are caused by pain. Neurological as well as muscular disorders can
cause of very typical gait abnormalities.
Look always how the dog sits down and stands up. This is a great tests to look for stifle problems. A dog
with painful stifle hesitates to flex its knee while sitting down and avoids full flexion. Thus it prefers to move
the foot outward to extend the stifle.
Next, inspect the standing dog. Look at the joint angulations, the loading and position of the feet and toes, look
for asymmetries, abnormal swellings or atrophies. Does the dog takes a specific posture while standing? Dogs
with lumbosacral pain for example often show a typical pelvic tilt with the tail pulled between the legs.
2. PALPATE & MANIPULATE THE DOG
This is best done, while the dog is standing or sitting. Use minimal restraint, try to keep the dog relaxed.
Stand behind the dog and start palpating the back, then the rear legs. Palpate both legs simultaneously. This
is the easiest way to detect subtle differences between the right and left leg.
Look for any abnormalities such as atrophies, swellings, abnormal heat, effusions, scar tissue, muscle spasms
or contractions, and pain etc. Do a deep palpation of the long bones to rule out pain. Check the local lymph
nodes.
Once the dog got used being touched and used to get manipulated, move all the joints through a full range
of motion.
I usually start with the rear legs. Gently lift up one leg and put all joints in full flexion, then gradually extend the hip. Do each manipulation on both legs, before you proceed to the next joint. Not all dogs show
obvious pain if you hit the sore spot. But most will show some resistance to a painful manipulation. Again,
subtle differences are best identified by comparing the two legs. Not only check for pain, but also degree of
range of motion (increased or decreased) and abnormal sounds or crepitus.
Partially flex the hip and hyperextend the stifle. Watch for pain response. Work your way down to the tarsus and foot. Careful palpate the toes and flexor tendons of the toes. Palpate the sesamoid bones of the
metatarsus.
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Check the lumbosacral and caudal lumbar area with the pelvic tilt and -lordosis test.
Have the dog sit down and repeat the exam with the front legs. Do not forget to manipulate the head and
neck. Try to motivate the dog to move his neck itself by offering him goodies. This will reveal subtle problems a lot better than any forceful manipulations, that most dog resists don’t like to begin with.
Gently lift up the paws and flex the elbow, then hyperextend the shoulder followed by hyperflexion of the
shoulder. Keep the shoulder slightly flexed and hyperextend the elbow only. Flex and extend the carpus.
3. PERFORM SPECIFIC EXAMINATIONS OF EACH JOINT
If a painful joint has been found, then perform specific tests to find the cause of the pain. A classical example is the tibia compression test to check for ACL rupture. If the palpations and manipulations did not help
to localize the problem, then all joints should be systematically examined.
Remember: the joint most commonly causing lameness of the rear in dogs is the stifle (most likely assoc with
ACL disease) and the joint most commonly causing lameness in the front limb is the elbow joint (most likely associated with medial coronoid disease). Thus: if a dog is lame on its front it is the elbow - if a dog is
lame on the rear it is the stifle, until proven otherwise.
A dog with sifle pain has a positive sit test. With a partially or fully torn ACL, there is usually a slight swelling
over the medial side of the stifle joint in the area of the medial collateral ligament (medial buttress). In the
very early cases of ACL tears, there is no obvious thickening yet, but the distinct groove between the medial femoral condyle and the tibia plateau is filled in and can’t be palpated. Pressure over this area does cause
a pain response if there is an ACL problem. To check the groove it is best to elevate the tibia and put the
stifle joint in a 90° flexion.
Do a tibial compression test and check the drawer movement. This can be well done in the standing dog.
Always compare to the healthy side to detect subtle differences!
Dogs with elbow pain caused by medial coronoid disease might assume a typical posture while sitting, pushing the elbows to the chest while they outward rotate the paws. To check for medial coronoid disease, flex
the elbow 90 degrees and palpate the area cranio-ventrally to the medial epicondyle. Normally, there should
be a distinct indentation and even firm pressure over this area is not painful. With medial coronoid disease
you might feel a slight effusion, some thickening and most of the time pain on firm pressure. If there is no
clear response, repeat the pressure, while you pronate and suppinate the elbow joint in 90° flexion and then
in hyperextension. These are probably the most sensitive tests to discover medial coronoid disease, In fact
the clinical findings are often more sensitive than the radiographs in the early course of the disease.
It can be challenging to rule out shoulder problems as a cause of the lameness. If a dog has a shoulder disease of clinical importance, there is usually some pain response during manipulation such as hyperextension
and hyperflexion, external and internal rotation as well as abduction. Always palpate the bicipteal tendon.
Check not only for pain, but also for swelling, nodules and irregularities.
If there is no pain on shoulder manipulation and the dog has a normal biceps tendon, it is very unlikely the
dog has a shoulder problem causing lamness.
Front limb lameness diagnosis can be much more challenging then in the rear leg. There are dogs with medial coronoid disease, that have no obvious clinical or radiological abnormalities. Therefore it is important
to examine all the other joints very carefully. If they are normal – it is the elbow, until proven otherwise.
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Complicazioni dell’artrodesi
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Complications of tarsal and carpal arthrodesis
Regensdorf (CH)
The carpus and tarsus are the most commonly arthrodesed joints in small animals. Successful arthrodesis is
achieved with cartilage debridement, autogenous cancellous bone grafting and rigid fixation of the joints. A
variety of fixation techniques have been described using lag screws, plates, pins or external fixation. Primary
goal of all techniques is a solid immobilization until the joint is fused. As for most surgical procedures, complications do occur. Complications are most likely in partial arthrodesis of the carpus and panarthrodesis of
the tarsus. In particular the tarsus seems to be difficult to arthrodese successfully. A high rate of complications has been observed and is the major reason for poor results. Complications in up to 100% of the cases
have been reported1,3. Implant failures, such as breakage or loosening, lack of joint fusion, osteomyelitis as
well as degenerative joint disease of the intertarsal or metatarsal joints are the most common complications
reported. Careful diagnosis of the underlying causes is important to treat the complications successfully.
The complications of tarsal and carpal arthrodesis can be divided in two general groups: complications associated with failure of the fixation and complications that result in poor limb function.
FIXATION FAILURE
Fixation failures have either mechanical or biological reasons. Lack of rigid fixation seems to be the most important mechanical factor leading to fixation failure. Lack of stability causes delayed fusion of the joint(s). This
increases the risk of implant failure due to chronic cycling loads. Inadequate implant strength, inadequate implant placement (i.e. dorsal plating) have been reported to be important factors for lack of stability2.
The implant selected is either too weak or insufficiently anchored to the bone. Insufficient anchorage of an
implant may lead to premature loosening of the fixation such as an ESF or a plate.
Optimal side of implant placement has always been a matter of debate. Plates are most conveniently placed
on the dorsal aspect of the joint surface, which is considered the compression side and therefore not the ideal side for plate placement. The tendon apparatus balances compression and tensions in the distal joints. Successful arthrodesis using dorsal plates can be achieved, provided the mechanics of the joint function are respected and there are no biological factors leading to a prolonged healing process. A typical reason for failure of a dorsally applied plate in tarsal panarthrodesis is lack of incorporation of the calcaneus in the fixation. Fixation of the calcaneus is important to neutralize the forces acting on the joint by the Achilles tendon
apparatus. Screws incorporating the distal tibia and/or the talus together with the calcaneus act as interlocking bolts to reduce the weight bearing stress on the plate.
Another important cause of implant failures is poor biology. Biological reasons such as lack of cancellous
bone graft, suboptimal debridement of the joint cartilage or infection and secondary osteomyelitis lead to
delayed healing or no fusion at all. This again increases the cycling load of the implants and thus the risk of
fatigue fractures or implant loosening. Careful analysis of the implant failure will reveal in a majority of cases biological causes as important contributing factors.
Insufficient removal of cartilage is more likely if the debridement was done by hand with a curette. This is
more time consuming, tiresome and less efficient, than debridement with a high-speed burr. Using a highspeed burr however can cause heat necrosis of the bone, if the bone is not cooled with saline.
Lack of fresh cancellous bone graft is another cause of failure. If there is no (or not enough) cancellous bone
graft used there is no scaffold for bone ingrowth and no promotion for rapid bone healing. Occasionally
there is simply not enough cancellous bone available for harvesting, esp. in older cats. In these cases it is important to augment the graft with BMP or similar products. The cancellous bone has to be packed in the
recipient site before the implants have been applied; otherwise it is difficult to place the graft well between
the joints spaces to be fused.
Fixation failures result in pain and non-union if left untreated. Revision is needed improving biology and
stability.
POOR LIMB FUNCTION
Poor limb function occurs in spite of a successful arthrodesis. This complication can be challenging to diagnose and frustrating to treat.
Poor limb function might be caused by a fixation that interferes with joint /limb function.
This is typically seen in partial carpal arthrodesis using a dorsally applied plate, which is not placed low
enough on the radio-carpal bone. When the dog is fully extending the joint during weight bearing such a
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plate will impinge on the joint capsule and/or the distal rim of the radius. The screws placed in the radio
carpal bone can cause poor limb function if they are too long and exit on the caudal joint surface of the radio-carpal bone. They interfere with the radial joint on full flexion of the carpus. Removal of the irritating
implant is needed to treat this complication.
Poor limb function can be caused by overload of adjacent joints and subsequent degenerative joint disease
with pain. This is most likely the result of a partial arthrodesis of the radio carpal- or talocrural joint that
overloads the small, tight distal joints. Overload of the calcaneal joints is one predominant causes of poor
limb function after a panarthrodesis of the tarsus. The calcaneus is quite mobile and there is a fair amount
of motion between the calcaneus and the talus as well as between the calcaneus and the quartal tarsal bone.
This motion increases during weight bearing as the Achilles tendon pulls on the calcaneus. The calcaneo-talar joint however is difficult to access and to fuse surgically. Therefore the only way to incorporate the calcaneus firmly in the arthrodesis is by fusing the calcaneo-quartal joint.
Fusion in malposition result in similar problems as a malunion of a fracture. Abnormal wear and tear of the
adjacent joint and toes, resulting in toe dragging, leads to poor limb function. If the angel of fusion is too
extended toe dragging is more likely, if it is to flexed, the gait abnormality is caused by a shortened stance
phase of the foot.
Contraction of the tendons is another complication leading to poor limb function.
The digital flexor tendons are most likely affected. The contraction is probably the result of direct trauma
and prolonged immobilization of the operated leg in a splinted bandage. Full extension of the metacarpal/
metatarsal.phalangeal joints is usually restricted and painful. A severe contraction was seen in a feline patient that had an arthrodesis of the tarsus due to a sciatic nerve injury. The contractions together with poor
sensation lead to severe ulcerations of the foot.
Contractions of the gastrocnemius muscle have been reported as another cause of poor limb function after
pantarsal arthrodesis. Five of 12 dogs with excellent or good function at a walk were less able to bear weight
on the arthrodesis limb when standing. This appeared to be associated with gastrocnemius tendon pain and
increased tension. One dog that had a gastrocnemius tenotomy was improved within 2 days.
Low-grade osteomyelitis is an other cause of lameness, as it causes chronic inflammation, pain and poor limb
function, which resolves only, once the plate is being removed.
REFERENCES
1.
2.
3.
4.
Doverspike M., Vasseur PB.: Clinical Findings and Complications after Talocrural Arthrodesis in Dogs. JAAHA
1991, 27: 553.
Gorse MJ, Early TD.; Aron D: Tarsocrural Arthrodesis: Long-Term Functional Results. JAAHA 1991, 27: 231.
KlauseSE, Piermattei DL, Schwarz PD: Tarsocrural Arthrodesis: Complications and Recommendtions. V.C.O.T.
1989, 3: 119.
McKee WM, May C et al.: Pantarsal arthrodesis with a customized medial or lateral bone plate in 13 dogs. Vet Rec,
2004, 154: 165.
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Planning nel trattamento
delle fratture nel gatto
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Fracture planning in cats
Regensdorf (CH)
“As long as the two ends of a broken cat bone share the same room, they will heal together” is a well-known
saying.
This common misconception is based on the fact that often young inexperienced cats are injured which have
an excellent healing potential, that cats have an excellent ability to protect themselves, as well as to compensate for handicaps and to hide their disabilities. However there is no clinical or experimental evidence
that cat fractures heal indeed better than those of dogs. Distal tibial and proximal ulnar fractures are well
known for their high risk of developing non-unions.
There is also no evidence, that complications are less common in cats than dogs. Complication rates up to
25% have been reported after repair of radius/ulnar fractures. It is therefore wise to take cats as fracture patients seriously and to provide them the best fracture treatment possible. A sound fracture planning is the
best basis for success and has to take the specific nature of cats into consideration.
Fracture planning not only involves the repair itself, but also the timing of the surgery, the preparation of
the animal, the set up of the operating room and client communication. Risks, potential complications and
prognosis of the proposed procedure as well as the costs must be discussed with the client and ideally, an informed owner consent obtained.
FRACTURE PLANNING - GENERAL CONSIDERATIONS
Good quality orthogonal radiographs of the fractured bone, including the adjacent joints are mandatory. Radiographs of the opposite bone are often helpful for fracture planning and implant pre-contouring.
Fracture planning should not only focus on the repair but also on all potential problems that might happen
during the surgery itself. This avoids prolonged operation time, excessive soft tissue trauma and technical
errors. The surgeon should be ready for the unexpected and always have a plan B and C if the initial plan
is not working.
The optimal fracture plan is not only based on the radiographs to evaluate the fractured bone, but also is
on the assessment of the injured limb and the patient. Assessment of the limb and the patient is important
to predict the healing potential of the fracture and the risk of complications. The healing potential affects directly the length of time implants must function to support the bone. Longer healing times are expected with
poor biology, because the soft tissue envelope has to heal first.
1. Assessment of the patient
Age, overall general health have an impact how well the fracture will heal and how to repair a fracture. Cats
have high life expectancy and geriatric fractures are not uncommon. The bones of geriatric cats are often
brittle, resulting in challenging comminuted fractures with poor biology and reduced healing potential. Concurrent injuries such as fractures of other limbs force the patient to bear excessive weight on the operated
leg and will stress the repair.
2. Assessment of the injured limb
The type of injury causing the fracture has also a direct impact on the degree of soft tissue trauma and the condition of the soft tissue surrounding the bone. High-energy trauma such road traffic accidents or gun shot injuries likely result in severe muscle lacerations and contusions and are often associated with extensive wounding of the skin. Severe open fractures occur more likely with juries of the distal extremity that has less soft tissue protection compared to the upper limb. Time span from injury to admission into the clinic, type of trauma
causing the injury and wound condition will predict how likely a wound or the fracture is already infected.
3. Assessing the fracture
An important step in planning the fracture treatment is to evaluate if the fracture is reducible or not.
Simple two-piece fractures such as transverse, short or long oblique fractures and fractures with 1-2 large
free fragments (butterfly fractures) are classical examples of reducible fractures. Once the bone column is
anatomically reconstructed it will have some inherited stability and there will be sharing of weight bearing
load with the implant.
Comminuted fractures are non reducible. As the bone column cannot be anatomically reconstructed there
is no load sharing between the bone and the implants. The implants have to carry all loads until callus
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is formed and are at risk to fail. A more rigid type of fixation with stronger implants is therefore mandatory.
Based on the collected information a fracture treatment plan is established. The ideal implant is selected, that
provides the required stability for the fracture to heal without untoward effects on the biology and function
of the patient.
The fracture treatment plan includes also the type of reduction to be used.
Reduction either aims at reconstruction of fractured bone fragments to their normal anatomic configuration
or restoring normal limb alignment only. This is also called indirect reduction, because the bone is realigned
without touching the bone fragments.
For anatomical reconstruction of reducible fractures that require interfragmentary stabilization an open reduction (OR) techniques is needed. OR is also used for most articular fractures.
OR has several advantages: it allows for better overall orientation (alignment) and also facilitates implant
placement. Cancellous bone graft can be applied to fill bone defects and augment bone healing.
If open reduction is selected to repair a non-reducible comminuted fracture, only enough exposure is made
for realigning the fracture and applying the implants, but the fracture fragments and blood clots are not
touched. This technique is also called “OBDNT” – Open But Do Not Touch.
Closed reduction (CR) is ideal for simple fractures that will be treated conservatively by external coaptation,
external skeletal fixation or IM pinning. It is also used for highly comminuted fractures that are treated by
minimally invasive osteosynthesis (MIO).
CR has the advantage that iatrogenic tissue trauma is minimized and blood supply is maximally preserved with
less post operative pain, faster healing and less risk of infection. It can result in a decreased operative time.
As open or closed reduction can be combined with internal or external fixation, the surgeon has theoretically 4 treatment options:
1. CREF – Closed reduction and external fixation with a cast, splint or an external skeletal fixator (ESF),
2. CRIF - Closed reduction and internal fixation of the fracture with minimal invasive osteosynthesis using
pins or plates,
3. OREF - Open reduction and external fixation with an ESF,
4. ORIF - Open reduction and internal fixation w/ pins, cerclage, screws and plates.
The optimal technique of repair should have the best chance for uneventful healing and return to full function, with the least additional trauma to patient and the least risk for complications.
THE CAT FACTOR
While planning the optimal repair, consider the fact that you are treating a cat, which is not just a small dog.
Some of the differences between the two species are:
1. Functional differences
Dogs have legs and paws - cats have arms and hands. They use their front legs for grooming, catching prey,
climbing and self defense. A pronounced pronation and suppination is vital for their limb function and must
be maintained. There are many more such adaptations that have to be taken into account when doing feline orthopedic surgery fracture repair.
2. Anatomical differences
There are specific as well as general anatomical differences between dogs and cats. The distal humerus for
example has a supracondylar foramen through which the median nerve passes. Medial plating of the feline
humerus is therefore not advisable.
Feline long bones are generally straight and uniform w/ a relatively large medullary cavity. This makes them
ideal for IM pinning or IL nailing.
The small sizes of bones and bone fragments makes reconstruction more difficult and rigid fixation often
impossible due to lack of appropriate implants.
In general the flat bones (ileum, mandible) and the cortex of the long bones are thin and the holding power of implants is reduced.
SECONDARY FACTORS
Once a treatment plan has been selected, it has to be re-evaluated in the light of secondary factors:
1. The surgeon and facilities
The surgeon must be confident to deal with the type of repair and should be able to handle all intra- and
postoperative complications if they occur.
All the implants and instruments necessary to perform the surgery properly should be available.
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2. The cat
Not every planned repair is compatible with the personality of the cat. A cast or an external fixation requiring an intensive post operative management might not be the best decision for a mean, non-compliant cat.
The treatment plan might be influenced whether the cat is an indoor or outdoor cat.
3. The owner
Client compliance, reliability and cooperation may influence the initial treatment plan. The success of a surgical repair depends strongly from the willingness and ability of the owners to attend to their patients postoperative needs. Client expectations need to be discussed.
Last but not least the owner has to pay for your treatment. Never take any negative assumption on the client
and take a decision for the client. Always give him the best treatment option for a given fracture. If the client
cannot afford it or is not willing to pay, discuss alternative repairs. It is an art to do a good job with limited resources! But costs can never be an excuse for doing a bad or sloppy job.
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Trattamento della rottura
del legamento crociato nei cani
di razza di piccola taglia e nei gatti
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Management of cruciate ligament rupture in small breed
dogs and cats
Regensdorf (CH)
Management of anterior cruciate ligament (ACL) ruptures in small- or toy breed dogs and cats have not received as much attention as the same condition in large breed dogs lately. In fact many surgeons feel, that
small breed dogs and cats do well enough with conservative management. There is convincing evidence,
that ACL ruptures should be treated with the same rational as done in large breed dogs.
There are however differences between large breed dogs and the small breeds dogs and cats.
The following presentation will discuss some of these differences of ACL rupture and treatment between
large breed dogs (LgBD) and small breed dogs (SmBD) and cats:
First, early partial or partial tears are not as commonly diagnosed in SmBD and cats. They usually have a
fully torn ligament at the time of clinical presentation. It is unclear however, why partial tears are less commonly seen. There are two possible explanations: 1. Partial tears do exist as well, but clinical signs are not
as obvious and as readily recognized in SmBD as in LgBDs - or - 2. ACL rupture in SmBD has a different
etiology and /or course of disease. While in dogs ACL ruptures are considered to be usually the result of a
degenerative disease, in cats they are mostly traumatic in origin.
Due to the synergistic function of the different stifle ligaments concurrent injuries have to be expected. It is
therefore not surprising, that almost 40% of the cats with ACL ruptures have additional stifle ligaments injured. Concurrent injuries to the medial collateral and posterior cruciate ligament are most common. These
result often in highly unstable knees or even stifle joint disruptions. As there is rarely a history of major trauma and concurrent stifle ligament injuries are seldom seen in SmBD, it is most likely, that the ACL is subject to chronic damage and degeneration in SmBD as in LgBD and the early signs of the disease simply go
unnoticed by the owner.
The average tibial slope in SmBD seems to be steeper and often excessive. This clinical impression is supported by one paper that reports an average inclination of the tibial slope of 27.4 degrees in SmBD (Petazzoni,
2004). This might put increased stress on the ACL. The average tibial slope in cats is less then in dogs and
has been reported to be 20.5° (+/- 4°) (Schnabel et al. Thesis, Univ of Vienna. 2006).
ACL ruptures associated with chronic medial patellar luxation is another common finding in SmBD. Medial patellar luxation rotates the proximal tibia inward, which results in an impingement of the ACL by the
medial condyle and directly leads to ligament failure.
MANAGEMENT
Surgical management is the preferred treatment also in toy breed dogs and cats with ACL rupture.
It has been reported, that cats do not need surgical repair and recover with conservative treatment as well.
In our experience surgical management is superior to return the cat to normal function compared to conservative treatment. Operated cats show faster recovery and seem to have a better overall prognosis. This
observation is supported by the fact, that 42% of the cats with ACL have also an injured meniscus.
The classical repair with a lateral suture and joint capsule imbrication is a quick and simple surgical procedure that results in an acceptable outcome in most dogs and cats. However suture failures resulting in unstable stifles do occur. This is becoming increasingly evident, as more and more small breed dogs are competing in sporting activities, such as agility. Isometric suture placement using suture anchors seems to eliminate some of the problems with the classical suture techniques, but optimal suture anchor placement is not
easy in the very small patient. Complications do occur and include fracture of the condyle, misplacement of
the anchor into the joint or rupture of the suture.
Similar to large breed dogs, TPLO is a viable alternative to the lateral suture techniques.
The TPLO procedure is technically somewhat more demanding due to the small size of the patients. Menisceal release by a caudo-medial approach - as done in LgBD - is possible, but inspection and removal of damaged portions of the medial meniscus is difficult due to the small field of view. A craniomedial approach to
the joint is a good alternative and allows for full inspection of the stifle joint.
However mensiceal release or resection is more difficult.
Even the small jig (Slocum Enterprises, USA) and its fixation pins are often too large and bulky for the SmBD.
If smaller fixation pins are used with the jig, they are not rigid enough to provide adequate stability. Therefore we are no longer using the jig in SmBD.
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The smallest saw blades available and most commonly used have a 12 mm radius. Some blades are rather
thick and remove a lot of bone while cutting. There are now thinner cutting blades available, that allow for
a fast and very precise cut.
The amount of rotation required to level the tibial plateau depends the radius of the osteotomy. To level a
35° slope to 5° with a 24 mm radius osteotomy 12.4 mm of rotation is required, With a Ø 12 mm osteotomy only 6 mm rotation is necessary. Thus the tibial crest is less exposed and the risk for an avulsion fractures is reduced.
Be aware, that cats have a rather flat tibial crest with a compact proximal tibia. This puts, cats are at risk to
sustain an avulsion fracture of the crest if the TPLO cut is performed to cranially.
The oscillating machines commonly used are rather bulky and make a precise cutting through the delicate
bones of SmBD difficult. Using a pin for rotation and temporary fixation of the proximal segment can be
somewhat clumsy. A pointed reduction forceps can be used instead of the rotation pin. This facilitates insertion of the temporary fixation pin.
For stabilization, Mini-instrumentation and -plates are needed. There are 2.0 mm TPLO plates available but
not all fit well in the very small patients. All provide enough stability for the osteotomy to heal. Be aware,
that long 2.0 mm cortical Mini-screws are needed and make sure you have them ready. There are 2.0 mm
cortical screws up to 34 mm long available (Synthes Vet, Paoli USA).
Plate placement might be difficult in some SmBD due to the conformation of the proximal tibia. They often have a very prominent tibial crest, a caudally curved proximal tibial shaft and / or a varus deformity of
the proximal tibia.
Even so TPLO in SmBD and cats is more demanding, it can be achieved without major difficulties or intra-operative complications and has shown to be an efficacious technique for the treatment of anterior cruciate ligament rupture.
LITERATURE
Petazzoni, M. TPLO in small breed dogs:18 cases. Abstract 12th ESVOT congress, Munich 2004.
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Fratture radio ulnari
nei cani di razza Toy
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Distal radial fractures in toy breed dogs
Regensdorf (CH)
Most fractures seen in toy breed dogs are managed very similar to those seen in regular or large breed dogs.
Obviously the major difference between toy and larger breed dogs is the size of the implants needed to stabilize the fractures. Thanks to the miniaturization of many implants, in particular of the plates and screws,
rigid internal fixation is nowadays feasible even in the smallest patient.
Fractures of the distal radius and ulna are the third most common fracture in dogs, but the incidence of these
fractures is particularly high in toy breed dogs. There seems to be an inherited weakness of the distal radius
in some toy breed dogs, as bilateral fractures or a fracture of the opposite radius to a later date are not uncommon. Usually the fractures are caused by minor trauma. Younger dogs (1-2 yrs) are most commonly affected.
Management of these fractures seems to be associated with a high rate of complications. Miniature breed of
dogs are reported to be particularly prone to non-union. Studies have shown, that when distal radial and ulna fractures in small and medium dogs were treated identically, delayed union and non-union complications
occurred primarily in the small-breed dogs.
Inherent biomechanical instability, decreased intra-osseous blood supply and a limited soft tissue envelope
for provision of extra-osseous blood supply for early revascularization and healing while the nutrient artery
redevelops, all these factors most likely contribute to the higher frequency of delayed union and non-unions
in toy breed dogs. Of these factors, the marginal blood supply in the distal radius of small and miniaturebreed dogs seems to be a major cause of delayed union or non-union. It has been shown that in small breed
dogs, there is a decreased vascular density and arborization of the vessels in the distal metaphysis as compared to larger breed dogs. This paucity of vessels results in a zone of reduced vascularity at the distal metaphyseal region of the radius in small dogs.
Biomechanical instability certainly is another major cause predisposing to non-union after fracture reduction. There is minimal bone surface contact resulting from the small bone size and the short oblique or transverse nature of many distal radius and ulna fractures. Instability in a small fracture gap associated with simple fractures is more devastating to fracture healing than the same amount of instability in a comminuted
fracture, where motion between the fragments is better distributed and thus diminshed.
Fixation of distal radius and ulna fractures in toy breed dogs with casts, intramedullary pins, external fixators and bone plates have been reported.
However eighty-three percent of distal radial fractures treated with cast fixation developed serious complications such as malalignement and non-union. Therefore casting is not an acceptable technique for fracture
stabilization. Intramedullary pinning is also not recommended because a) it fails to adequately counteract rotational forces, b) the pin is difficult to insert without interfering with the carpal joint and c) the pins that can
be inserted safely are too weak to effectively stabilize the fractures. Therefore it is not surprising, that complication rates are unacceptably high with this technique, being 80% as reported in one study.
Open or closed reduction and external fixation have been advocated for adequate stabilization of distal radius
and ulna fractures. Because several pins have to be inserted within a very short distance, the size of most
–even small - clamps is often too big to bring them as close together as needed. One exception is the MiniFESSA® System initially designed by the French army. It allows for inserting within a very short distance
several fixation pins in the bone directly through the FESSA-connecting bar. Alternatively, many surgeons
use a free moldable acrylic (PMMA) to connect the fixation pins.
Reported complications associated with ESF include pin loosening, pin tract infections, mal-alignment and
- rarely - delayed union or nonunion.
Open reduction and internal fixation using Mini plates is the authors preferred technique. Depending how
distal the fracture is, a 5 – 9 hole 2.0 DCP plate is used. Note however, that the 6 mm 2.0 DCP is available
at a thickness of 1.5 and 1.0 mm. The stronger plate is preferred in most instances. The 2.0 DC - plate allows compression of the fracture by 0.6 mm, provided the appropriate load guide is used. If the fracture is
very distal, a Veterinary Mini-T plate might be used. Due to the size and shape of the bone, the plate is best
applied on the dorsal side of the bone.
Even so there is usually enough room to use the stronger 2.0 mm screw, I prefer to use the 1.5 mm screw
to fix the plate to the bone, if possible. It is the impression, that this screw does less damage to the bone and
screw loosening is not a problem. Using the 1.5 mm screw also diminishes the risk of a fracture through an
open screw hole, once the plate is being removed.
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Perfect alignment is important. It seems that catastrophic failures with break down of the fixation due to
plate failure or screw pull out primarily occurs in cases where fracture reduction was inadequate or the fracture malaligned. Mild transient osteopenia can occasionally be seen, but does not seem a clinical problem.
If fracture fixation using Mini-DC plates is properly performed, the risk of delayed or non-unions in toy
breed dogs is not higher than in any other breed of dogs. Other complications occasionally reported are skin
erosions over the distal plate end, thermal conduction, synostosis between radius and ulna and decreased
ROM in the carpal joint.
Due to the distal location of the fracture and the vascularity problems assoc with these fractures, the use of
2.0 LCP might become an interesting alternative. In the very small toy dogs we also used with good success
the compact hand plates. They are used with 1.3 mm screws.
Overall plate fixation provides a successful method of repair of distal radius fractures in toy breed dog resulting in good to excellent outcome in the majority of cases.
REFERENCES
Welch, JA et al.: The intraosseuos blood supply of the canine radius: implications for healing of distal fractures in small
dogs. Vet surg 1997, 26:57-61.
Summer-Smith GA: A comparative investigation into the healing of fractures in miniature poodles and mongrel dogs. J
Sm Anim. Pract. 1974: 15:323-8.
Summer-Smith GA: A histological study of fracture nonunion in small dogs. J SM Anim Pract 1974: 15:571-8.
Campell JR: Healing of radial fractures in miniature dogs. Vet annual 1980; 20 106-12.
Wilson JW: Vascular supply to normal bone and healing fractures. Sem Vet Med and Surg 1991 6:26-38.
Larsen LJ et al: Bone plate fixation of distal radius and ulna in small-and miniature-breed dogs JAAHA 1999, 35: 243-50.
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