Surgical Treatment of Suspensory Desmitis

SURGICAL TREATMENT OF SUSPENSORY DESMITIS
Nathaniel A. White II DVM MS, Diplomate ACVS
Marion duPont Scott Equine Medical Center
VMRCVM-Virginia Tech, Leesburg, Virginia
Rest is the most common treatment for suspensory desmitis. The greatest success with
no relapse includes absolute stall rest for 4 weeks prior initiating controlled and gradually
increasing walking concurrent with stall rest. Once the core lesion has filled and the fiber
density is increased and uniform, walking under saddle can be initiated. Most suspensory
ligaments require 2-3 months of healing prior to starting any work at the trot, which is completed
prior to turnout. Monthly ultrasound examinations are recommended, to ensure exercise does
not exceed the limits of ligament strength as exercise is increased. Though the prognosis
depends on the severity of injury, most injuries of front limb proximal suspensory ligament
injuries heal with rest. Ninety percent success for healing proximal suspensory desmitis in the
front limbs has been reported, whereas only 0- 50% of proximal suspensory injury in the rear
limbs heal with rest. Repeat- injury rate was higher in horses with larger core lesions (core was
52% of the cross sectional area vs. 25.7% core in race horses).
Suspensory ligament injury appears similar to tendinitis on ultrasound with chronic
injuries maintaining an anechoic core lesion and failure of normal fiber alignment. Specimens
from failing suspensory ligaments indicate a lack of healing with both foci of unorganized
fibroplasia and acellular region with no vascularity and nesting of desmocytes attempting to
initiate healing (Figure 1). These lesions are suggestive of a decreased vascularity potentially
due to the type of tissue injury as well as increased compartment pressure as described for acute
tendon injuries.
Recent treatments reported for suspensory desmitis include BAPTN injection, bone
marrow injection into the core lesion, shock wave therapy and fasciotomy with neurectomy (for
rear limb proximal suspensory desmitis). BAPTN is no longer available and the evaluation of its
use in the suspensory ligament is incomplete. Bone marrow injection has been reported as a way
to stimulate healing using stem cells. The results, from cases, which did not respond to rest, are
encouraging but both front and rear limb suspensory desmitis were reported together so it was
difficult to determine the benefit of bone marrow treatment between front and rear limbs. No
control for the injection of a large volume of fluid into the suspensory ligament has been
completed. Anecdotal results suggest that shock wave therapy has been successful particularly
for injuries to the origin of the suspensory ligament (approximately 40-70%). Use in rear limb
proximal suspensory desmitis has resulted in resolution and return to work in 40% of cases.
Fasciotomy with concurrent neurectomy of the deep plantar nerve was successful in 19 of 20 rear
limb proximal suspensory desmitis cases.
Anecdotal results to other treatments including
injection of hyaluronate or polysulfated glycoaminoglycan, and application of therapeutic
ultrasound have had mixed success.
Suspensory desmoplasty (surgical fasciotomy and splitting) has been used for several
decades in resistant cases of suspensory desmitis similar to tendon splitting, but there are no
reports of the technique or follow-up after surgery. The technique is similar to splitting tendons
though the results for chronic non-healing lesions is much better than for tendons. Surgery is
successful for injuries that did not healed adequately with rest from 2 months up to 1-2 years.
Case selection is based on inadequate core lesion healing and with most lesions at the origin of
the suspensory or at its insertion on the proximal sesamoid bone. Desmitis of the oblique
sesamoid ligament can also been treated with this technique. In cases where fiber defects are
present at the interface of the suspensory ligament and the sesamoid bone (Figure 2) or
MCIII/MTIII (Figure 3) the bone was scored with the scalpel during the procedure.
Ultrasound is used to guide the surgical incision. For lesions at the attachment to the
sesamoid bone the suspensory is split to the bone by guiding the scalpel in the core lesion until it
contacts bone. This is best done with the horse under general anesthesia to allow proper
positioning of the ultrasound head and to ensure no movement when directing the scalpel to the
core and scoring the bone. Multiple stabs along the length of the lesion are made to penetrate
entire lesion. This usually only requires three to five percutaneous incisions along the side of the
suspensory branch.
Splitting and fasciotomy of the front and rear proximal suspensory ligaments is also
completed with the horse under general anesthesia. Percutaneous incisions are made from the
lateral surface. The scalpel is guided by ultrasound to the anechoic region in the suspensory and
includes scoring of the bone surface (Figure 4). The stab incisions are continued until the full
length of the core lesion is opened. One split is made at the center of the core lesion unless it is
very large in which case the scalpel may be redirected through the same skin incision to open
adjacent regions of the core lesion. Though not visualized the linear placement of the incisions
create a fasciotomy as part of this procedure. The distance between incisions is approximately
the length of the scalpel blade to ensure that the fascia is opened along the entire length of the
core lesion. Sutures are not required for the small stab incisions.
Postoperative care is similar to tendon splitting except that the ligaments often do not
require as long to heal. Suspensory branch lesions will heal adequately in 3-6 months.
Experience with desmoplasty at suspensory attachment injuries suggests injuries at the origin and
insertion take up a minimum of six months and some times as much as a year before the horse is
in full work.
To date 95% of horses with of rear limb proximal suspensory desmitis, which did not
heal with rest or rest and shock wave therapy healed and returned to work after suspensory
desmoplasty. Eighty percent of lesions at the insertion of the suspensory ligament on the
sesamoid bone have healed with horses return to their original level of work.
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Proc 40th AAEP Ann Conv. 1994; pp 183-185.
2. Cowles RR. Proximal suspensory desmitis- A Qualitative Survey. Proc AAEP Ann. Conv.
2000; 46:143-144.
3. Crowe O, et al. Treatment of 45 cases of chronic hindlimb proximal suspensory desmitis by
radial extracorporal shockwave therapy. Proc AAEP Ann Conv. 2002; 48:322-325.
4. Dyson S. Proximal suspensory desmitis in the forelimb and the hindlimb. Proc AAEP Ann
Conv. 2000; 46: 137-142.
5. Henninger RW, Bramlage LR, Bailey M, Bertone AL, Weisbrode SE. Effects of tendon
splitting on experimentally-induced acute equine tendinitis. Vet and Comp. Ortho Traumatology
1992; 5:1-9.
6. Herthel DJ. Suspensory desmitis therapies. Proc 12th ACVS Vet Sympo. 2002, pp 165-167.
Figure 1A
Figure 1B
Figure 1A: Normal suspensory ligament . Figure 1B: Disorganized fibroplasia from a case of
chronic proximal rear suspensory desmitis with loss of fetlock support.
Figure 2: A suspensory attachment lesion on the
sesamoid bone. The anechoic fibers (arrow)
adjacent to the sesamoid bone had not healed after
3-4 months of rest and improved after surgical
splitting with penetration to the bone with the
surgical blade.
Figure 3: Proximal suspensory desmitis at its
origin on MTIII. These hypoechoic lesions
(arrows) usually involve the attachment to the
cannon bone. There are often changes on the
cannon bone, which may or may not be detected by
ultrasound or radiography.
Figure 4: Ultrasonogram of suspensory desmoplasty with the blade
guided into the core lesion to the bone to complete a fasciotomy and
open the core lesion.