The PCL in TKR: to preserve or to cut ??

The PCL in TKR:
to preserve or to cut ??
Francesco Giron
SOD Traumatologia e Ortopedia Generale
AOU Careggi –Firenze
Director: Prof. R Buzzi
…a 25 years old dilemma !
Aglietti’s last 25 years:
P. Aglietti
J. Insall
PS: 90%
MBK (CR-mobile): 10%
CR vs PS: Controversy
Kinematics
Roll-back
Flexion
Clinical
Gait
Proprioception
Strength
Surgical
Exposure
Joint line
Balancing
Results
Patella
Loosening
Instability
Wear
CR vs PS: Controversy
Kinematics
Roll-back
Flexion
Clinical
Gait
Proprioception
Strength
Surgical
Exposure
Joint line
Balancing
Results
Patella
Loosening
Instability
Wear
Roll -back
Four-bar linkage
Motion is guided along a unique
path by constant tension
fascicles of ACL & PCL
W. Müller, 1982
Posterior Cruciate Ligament
Provides 95% of total
restraint to posterior
displacement of the tibia
on the femur
Tensile forces increase
with knee flexion
Posterior Cruciate Ligament
Allows femoral condyles to glide and rotate
posteriorly.
Posterior Cruciate Ligament
Roll back occurs during
knee flexion which
benefits:
Posterior clearance
Increased quadriceps
moment arm
Dynamic MRI studies
Medial Condyle
Lateral Condyle
Tibial internal rotation in flexion
Freeman, JBJS-B 2000
Lateral mobility:
1) Mobility of
lateral meniscus
Lateral mobility:
1) Mobility of
lateral meniscus
2) Lateral plateu
convex and downsloped
Lateral mobility:
LFC
1) Mobility of
lateral meniscus
2) Lateral plateu
convex and downsloped
3) Longer distal radius LFC
MFC
Medial stability:
1) Fixed medial meniscus
Medial stability:
1) Fixed medial meniscus
2) Medial plateu
cup-shaped & “upsloped”
Medial stability:
1) Fixed medial meniscus
PCL
2) Medial plateu
cup-shaped & “upsloped”
3) Ligament colums in
tension
LFC
MFC
MCL
PCL tension
PCL elongation (%)
25
20
15
10
5
0
20°
40°
60°
80°
100°
120°
PCL tightens from 45° to more flexion
Freeman, NOV-BVOT 2002
Kadoya, in press
Roll -back : PS knees
LFC
Knee 1
Knee 2
Knee 3
Knee 4
Knee 5
AP position (mm)
4
0
-4
-8
-12
0°
30°
60°
Knee flexion
90°
120°
Predictable kinematics
Dennis D, CORR 1996
Roll -back : CR knees
Symmetric condylar design
LFC
Knee 1
Knee 2
Knee 3
Knee 4
Knee 5
AP position (mm)
4
0
-4
-8
-12
0°
30°
60°
Knee flexion
Erratic pattern
90°
120°
Roll -back : CR knees
Asymmetric condylar design
LAT
MED
19/20 subjects experienced av. 4 mm lat. roll-back
Bertin KC, Komistek RD, J. Arthropl 2002
Asymmetric condylar design
AP position (mm)
LFC
0 Anterior
Posterior
Surgeon A
-5
Surgeon B
p<.05
-10
0°
30°
60°
90°
Nozaki H, CORR 2002
Maximum flexion
Tanzer M.
Non weight-bearing
CR
PS
Nexgen 112°
Nexgen 111°
AMK
108°
AMK
108°
Apollo
120°
Apollo
119°
Y/S
114°
Y/S
117°
AGC
111°
IB-I
112°
*bilateral knees
J. Arthropl. 2002
Rorabeck C.H.
CORR 2001
Dorr L.D.
CORR 2000
Shoji H. *
CORR 1994
Becker M.W. *
CORR 1991
Weight-bearing
PFC CR
103°
PFC PS
113°
p<.02
Dennis D. J. Arthropl 1998
CR vs PS: Controversy
Kinematics
Roll-back
Flexion
Clinical
Gait
Proprioception
Strength
Surgical
Exposure
Joint line
Balancing
Results
Patella
Loosening
Instability
Wear
Gait analysis
+
CS knees were less normal than CR
Andriacchi, JBJS-A 1982
Gait analysis (stair climbing)
14 bilateral TKR: one CR, one PS
60°
Degree
Knee
flexion angle
40°
20°
Knee
flexion moment
% Body weight
*leg length
100%
0
100%
-2
CR
PS
-4
-6
Percent of cycle
No difference
Wilson, J. Arthroplasty 1996
Bolanos, J. Arthroplasty 1998
Proprioception
Position sense (electrogoniometer)
CR better
Warren, CORR 1993
No difference
Simmons, CORR 1996
Cash, CORR 1996
Lattanzio, J. Arthropl. 1998
Wada, CORR 2002
Strength
No differences
in isokinetic strength
Huang, J. Arthropl. 1998
Ishii, J. Orthop. Sci. 1998
Wada M, C0RR 2002
CR vs PS: Controversy
Kinematics
Roll-back
Flexion
Clinical
Gait
Proprioception
Strength
Surgical
Exposure
Joint line
Balancing
Results
Patella
Loosening
Instability
Wear
MIS surgery
More difficult PS stemmed component insertion
Easier insertion with unstemmed CR tibial components
Modular PS stemmed component
PCL balancing is difficult
Normal PCL strain
Lotke PA, Am. J. Knee Surg. 1993
10%
Mahoney OM, J. Arthropl 1994
37%
Incavo SJ, CORR 1994
25%
PCL too tight
Limited flexion
Excessive posterior poly
contact stress and shear
forces due to exaggerated
rollback
Rocking movement of the tibial
component may precipitate
loosening, especially in
uncemented cases.
Poly lift-off in flexion
Increased femoral rollback in flexion with
posterior 1/3 contact rather than mid 1/3
contact of the tibiofemoral articulation
PCL too lose
Flexion instability
Pagano, CORR, 1998
May occur in the CR TKAs with
prior patellectomy
Laskin, JBJS, 1995
Possible increase in poly wear due
to cyclic sliding
Walker, ORS, 1991
PCL deficiency in rheumatoid
patients with recurrent synovitis
Laskin, CORR, 1997
PCL release often required
Ritter, J. Arthropl. 1988; Scott, CORR 1994;
Worland , J. Arthropl. 1997; Arima-Whiteside, CORR 1998
Severe deformity (varus>15°)
65 Tricon-CR vs 50 IB-PS
CR showed worse
clinical results &
higher revision rate
Laskin, CORR 1996
Joint line
Possible problem in PS knees
F/E gaps changes after PCL section
Cadaveric measurements
Gap increase (mm)
8
6
4
p<0.05
2
Extension
Flexion
Mihalko-Krackow, CORR 1999
Kadoya, CORR 2001
F/E gaps changes after PCL section
Gap increase (mm)
Intraoperative measurements
2.0
1.5
p>0.05
1.0
0.5
Extension
Flexion
Baldini-Scuderi, J Arthropl in press
Joint line height
J.L. (cm)
PS
CR
Preop.
2.2
2.2
Postop.
2.4
2.5
Cope-O’Brien, J. Arthroplasty 2002
CR vs PS: Controversy
Kinematics
Roll-back
Flexion
Clinical
Gait
Proprioception
Strength
Surgical
Exposure
Joint line
Balancing
Results
Patella
Loosening
Instability
Wear
Patellar problems
PS knees
Hozack, CORR 1989
Patellar clunk
Rounded
edge
Original IB-I
21 %
Modified IB-I
5%
Deep and prolonged
throclea
IB-II
LPS
Deepened and prolonged
throclea
Less prominent
shoulder
Synovial entrapment
Distally prolonged
throclea
Incidence
AMK-PS
AMK-PS
congruency
PFC-PS
13.5%
3.8%
0%
p<0.01
Pollock D.C., Engh G.A., JBJS-A 2002
Flexion instability
More of a problem with old design CRs
202 AMK (FU: 4 yrs)
8% AP instability
Waslewski, J. Arthropl. 1998
Clinical features
Persistent pain
Sense of instability
Recurrent effusions
Pes and retinacular tenderness
Posterior drawer sign
Above average range of motion
Rupture force (N)
Reduced PCL strength
600
300
Healthy
OA
p<.0001
Alexiades, Scott, AJKS 1989
Hagena, Int Orthop 1989
Rheumatoid arthritis
F.U. (yrs) Flexion instability
Laskin, Tricon-M
8.2
40%
11.0
2%
10.5
3%
CORR 1997
Schai-Scott, PFC
CORR 1999
Archibeck, MG-I
JBJS-A 2001
PS knees
2 mm
Dislocation
2 mm
IB I
0.6 %
IB II
0.2 %
Lombardi, J. Arthropl. 1993
Loosening
PS knees
All poly (IB-I)
F.U. Loosening
10 yrs
3%
11 yrs
0%
8 yrs
0%
Stern, JBJS-A 1992
Monoblock Metalback (IB-I)
Colizza, JBJS-A 1995
Modular (IB-II)
Aglietti, J. Arthropl. 2002
CR knees
Monoblock Metalback (AGC)
F.U. Loosening
15 yrs
0.4%
Monoblock Metalback (Kinematic-I) 16 yrs
1.7%
Ritter, CORR 2001
Rand, CORR 2001
Modular (MG-I)
Berger, CORR 2001
11 yrs
0.0%
Wear
CR old mistakes
Flat on flat
Thin poly
Heat compression
PCL tension
If the PCL is retained the tibial component
needs to be flat in AP plane.
Kinetic Conflict
Posterior impingement occurs with PCL
retention and dished tibial component
PCl retention see-saw effect
Flat tibial tray, poor articular conformity,
leads to increased contact stresses and
increased wear
Contact stress (MPa)
4
3
1
5
2
1
1.5
1
1
1
5
20
10
15
Radius ratio R2/R1
25
Increasing conformity reduces stresses
Andriacchi, 1993
Retrieved CR inserts
Flat
Curved
Length of implantation (yrs)
4.5
8.5
Linear wear (mm/year)
0.4
0.2
959
356
Volumetric wear (mm3/year)
Benjamin, CORR 2001
Meniscal Bearing Knee
Full conformity
Constant posterior
condylar radius
(spherical condyles)
Malrotation in fixed CR
MPa
30
25
CO
20
N
FO
IN
RM
G
T
35
FL
A
Implant stresses
40
15
10
5
Axial rotation
0
0
1
2
3
4
5
6
7
8
9
10
More stresses if conforming
D’Lima-Colwell, CORR 2001
Malrotation in fixed vs mobile CR
MPa
50
45
40
35
30
Fixed
Mobile
25
20
15
10
5
0
Neutral
15° E.R.
15° I.R.
Stresses are lower for mobile CR
Matsuda, J. Arthropl., 1998
Wear in PS
wear (gr)
Traditionally less of a problem
due to improved conformity
0,150
0,140
0,130
0,120
0,110
0,100
0,090
0,080
0,070
0,060
0,050
0,040
0,030
0,020
0,010
0,000
IB-I
IB-II
1
2
3
4
5
cycles in the lab (million)
Walker, Proc Inst Mech Eng, 1998
Walker, CORR, 2000
Tibial post wear: a new entity
Pulosky, JBJS-A, 2001
Hyperextension
Hyperextension
Flexed femoral component
Hyperextension
Flexed femoral component
Malrotation
Hyperextension
Flexed femoral component
Malrotation
Femoral component lift-off
Wear score/period of implantation
Wear location
Anterior
Posterior
Medial
Lateral
.08
.04
Kinematic
Kinemax
Genesis
AMK
IB-II/CCK
Coordinate
Pulosky, JBJS-A, 2001
Backside wear: CR & PS
Axial load
Shear forces
Elastic
deformation
Micromotion
Wasielewski, CORR 2002
Parks-Engh, CORR 1998
Implant sources of micromotion
Common to both prostheses:
Locking mechanism
Conformity
PS specific:
Cam & post
Long-term results
PS knees
F.U.(yrs) E/G Survivorship
Aglietti, 1999
IB-I
10
83%
92%
Li-Bentley, 1999 IB-II
10
94%
92%
Vince, 2000
IB-I
12
84%
92%
Insall, 2001
IB-I
10
96%
96%
IB-II
10
95%
98%
CR knees
F.U.(yrs) E/G Survivorship
Rand, 1995
Kinematic
10
87%
96%
Schai-Scott, 1998
PFC
10
--
90%
Berger, 2001
MG-I
11
84%
84%
MG-II
9
92%
100%
AGC
11
--
99%
Ritter, 2001
Conclusions
After 25 years of Socratic debate, there is no
clear advantage of one solution to the other.
Keep in mind that not all designs
are the same, in both types
If the results are equal, it is preferable to use
the easier technique
My suggestion: use what you know best.
“Excellence is not a singular act, but a habit:
you are what you repeatedly do.”
Aristotle