The PCL in TKR: to preserve or to cut ?? - Unimololdweb.unimol.it/unimolise/allegati/54074/Giron.pdf · The PCL in TKR: to preserve or to cut ?? Francesco Giron ... Mobile MPa Neutral

The PCL in TKR:

to preserve or to cut ??

Francesco Giron

SOD Traumatologia e Ortopedia Generale AOU Careggi –FirenzeDirector: Prof. R Buzzi

…a 25 years old dilemma !

Aglietti’s last 25 years:

PS: 90%

MBK (CR-mobile): 10%

P. Aglietti J. Insall

Kinematics Roll-back Flexion

Gait Strength Proprioception

Exposure Balancing Joint line

Patella Instability Loosening Wear

CR vs PS: Controversy

Results

Surgical

Clinical




Results

Surgical

Clinical



W. Müller, 1982

Roll -back

Motion is guided along a unique

path by constant tension

fascicles of ACL & PCL

Four-bar linkage

Posterior Cruciate Ligament

Provides 95% of total restraint to posterior displacement of the tibia on the femur

Tensile forces increase with knee flexion


Allows femoral condyles to glide and rotate

posteriorly.


Roll back occurs during knee flexion which benefits:

Posterior clearance

Increased quadriceps moment arm

Tibial internal rotation in flexion

Freeman, JBJS-B 2000

Medial Condyle Lateral Condyle

Dynamic MRI studies

Lateral mobility:

1) Mobility of

lateral meniscus

Lateral mobility:

1) Mobility of

lateral meniscus

2) Lateral plateu

convex and downsloped

Lateral mobility:

1) Mobility of

lateral meniscus

2) Lateral plateu

convex and downsloped

3) Longer distal radius LFC

LFC

MFC

1) Fixed medial meniscus

Medial stability:


2) Medial plateu

cup-shaped & “upsloped”

Medial stability:


2) Medial plateu

cup-shaped & “upsloped”

3) Ligament colums in

tension

MFCLFC

MCLPCL

Medial stability:

Freeman, NOV-BVOT 2002Kadoya, in press

0

5

10

15

20

25PCL elongation (%)

20° 40° 60° 80° 100° 120°

PCL tightens from 45° to more flexion

PCL tension

Roll -back : PS knees

Knee flexion

Dennis D, CORR 1996

Predictable kinematics

0° 30° 60° 90° 120°

0

4

-4

-8

-12

AP position (mm)

Knee 1Knee 2Knee 3Knee 4 Knee 5

LFC

Knee flexion

Roll -back : CR knees

0° 30° 60° 90° 120°

0

4

-4

-8

-12

AP position (mm)

Knee 1Knee 2Knee 3Knee 4 Knee 5

Symmetric condylar design

Erratic pattern

LFC

19/20 subjects experienced av. 4 mm lat. roll-back

Asymmetric condylar design

Bertin KC, Komistek RD, J. Arthropl 2002

MEDLAT

Roll -back : CR knees

Surgeon A

0° 30° 60° 90°

0

-5

-10

AP position (mm) Anterior

Posterior

Surgeon B

p<.05

Nozaki H, CORR 2002

Asymmetric condylar designLFC

Maximum flexion

CR PS

Tanzer M. Nexgen 112° Nexgen 111°J. Arthropl. 2002

Rorabeck C.H. AMK 108° AMK 108°CORR 2001

Dorr L.D. Apollo 120° Apollo 119°CORR 2000

Shoji H. * Y/S 114° Y/S 117°CORR 1994

Becker M.W. * AGC 111° IB-I 112°CORR 1991 *bilateral knees

Non weight-bearing

PFC CR 103°

PFC PS 113°p<.02

Dennis D. J. Arthropl 1998

Weight-bearing




Results

Surgical

Clinical



Gait analysis

CS knees were less normal than CR

Andriacchi, JBJS-A 1982

+

Wilson, J. Arthroplasty 1996Bolanos, J. Arthroplasty 1998

14 bilateral TKR: one CR, one PS

No difference

Knee flexion angle

Knee flexion moment

Gait analysis (stair climbing)

Percent of cycle

100%

100%

20°

40°

60°

0

-6

-4

-2

Degree

% Body weight

*leg length

PSCR

CR better

Warren, CORR 1993

No difference

Simmons, CORR 1996

Cash, CORR 1996

Lattanzio, J. Arthropl. 1998

Wada, CORR 2002

Position sense (electrogoniometer)

Proprioception

Huang, J. Arthropl. 1998Ishii, J. Orthop. Sci. 1998

Wada M, C0RR 2002

No differences

in isokinetic strength

Strength




Results

Surgical

Clinical



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 flexionExcessive 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 instabilityPagano, CORR, 1998

May occur in the CR TKAs with prior patellectomyLaskin, JBJS, 1995

Possible increase in poly wear due to cyclic slidingWalker, ORS, 1991

PCL deficiency in rheumatoid patients with recurrent synovitisLaskin, 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

Laskin, CORR 1996

CR showed worse

clinical results &

higher revision rate

Joint line

Possible problem in PS knees

Mihalko-Krackow, CORR 1999

Cadaveric measurementsGap increase (mm)

2

4

6

8

Extension Flexion

p<0.05

F/E gaps changes after PCL section

Kadoya, CORR 2001

Intraoperative measurements

Baldini-Scuderi, J Arthropl in press

F/E gaps changes after PCL section

Gap increase (mm)

0.5

1.0

p>0.05

Extension Flexion

1.5

2.0

Cope-O’Brien, J. Arthroplasty 2002

PS CR

Preop. 2.2 2.2

Postop. 2.4 2.5

Joint line height

J.L. (cm)




Results

Surgical

Clinical



Hozack, CORR 1989

Patellar problemsPS knees

Original IB-I Modified IB-I

Patellar clunkRoundededge

21 % 5 %

Deep and prolonged throclea

IB-II

LPS

Deepened and prolonged throclea

Less prominentshoulder

Distally prolonged throclea

Synovial entrapment

Incidence 13.5% 3.8% 0%p<0.01

Pollock D.C., Engh G.A., JBJS-A 2002

AMK-PS AMK-PScongruency

PFC-PS

Flexion instability

More of a problem with old design CRs

202 AMK (FU: 4 yrs)8% AP instability

Waslewski, J. Arthropl. 1998

Persistent pain

Sense of instability

Recurrent effusions

Pes and retinacular tenderness

Posterior drawer sign

Above average range of motion

Clinical features

Healthy

Alexiades, Scott, AJKS 1989Hagena, Int Orthop 1989

Reduced PCL strength

OA

300

600

Rupture force (N)

p<.0001

Rheumatoid arthritis

F.U. (yrs) Flexion instability

Laskin, Tricon-M 8.2 40% CORR 1997

Schai-Scott, PFC 11.0 2% CORR 1999

Archibeck, MG-I 10.5 3%JBJS-A 2001

PS knees

Lombardi, J. Arthropl. 1993

IB I 0.6 %

IB II 0.2 %

Dislocation

2 mm2 mm

F.U. Loosening

All poly (IB-I) 10 yrs 3%Stern, JBJS-A 1992

Monoblock Metalback (IB-I) 11 yrs 0%Colizza, JBJS-A 1995

Modular (IB-II) 8 yrs 0%Aglietti, J. Arthropl. 2002

LooseningPS knees

F.U. Loosening

Monoblock Metalback (AGC) 15 yrs 0.4%Ritter, CORR 2001

Monoblock Metalback (Kinematic-I) 16 yrs 1.7%Rand, CORR 2001

Modular (MG-I) 11 yrs 0.0%Berger, CORR 2001

CR knees

Flat on flat

Thin poly

Heat compression

PCL tension

CR old mistakes

Wear

If the PCL is retained the tibial component needs to be flat in AP plane.

Posterior impingement occurs with PCL retention and dished tibial component

Kinetic Conflict

PCl retention see-saw effect

Flat tibial tray, poor articular conformity, leads to increased contact stresses and

increased wear

Andriacchi, 1993

Increasing conformity reduces stresses

4

Contact stress (MPa)

3

2

1

5 10 15 20 25Radius ratio R2/R1

1

1

1

1

5

1.5

Benjamin, CORR 2001

Retrieved CR inserts

Length of implantation (yrs) 4.5 8.5

Linear wear (mm/year) 0.4 0.2

Volumetric wear (mm3/year) 959 356

Flat Curved

Meniscal Bearing Knee

Constant posterior

condylar radius

(spherical condyles)

Full conformity

More stresses if conforming

0

5

10

15

20

25

30

35

40

0 1 2 3 4 5 6 7 8 9 10

Axial rotation

MPa

CONFORMING

FLAT

Malrotation in fixed CR

D’Lima-Colwell, CORR 2001

Implant stresses

Stresses are lower for mobile CR

05

10

152025

303540

4550

FixedMobile

MPaMPa

Neutral 15° E.R. 15° I.R.

Matsuda, J. Arthropl., 1998

Malrotation in fixed vs mobile CR

0,0000,0100,0200,0300,0400,0500,0600,0700,0800,0900,1000,1100,1200,1300,1400,150

1 2 3 4 5

cycles in the lab (million)

wea

r (g

r)

Wear in PS

Traditionally less of a problem due to improved conformity

Walker, Proc Inst Mech Eng, 1998Walker, CORR, 2000

IB-IIB-II

Tibial post wear: a new entity

Pulosky, JBJS-A, 2001

Hyperextension

Hyperextension

Flexed femoral component

Hyperextension


Malrotation

Hyperextension


Femoral component lift-off

Malrotation

Wear location

.04

.08

Wear score/period of implantation

KinematicKinemax

Genesis AMKCoordinate

IB-II/CCK

AnteriorPosteriorMedialLateral

Pulosky, JBJS-A, 2001

Backside wear: CR & PS

Axial load

MicromotionElastic

deformation

Shear forces

Wasielewski, CORR 2002Parks-Engh, CORR 1998

Implant sources of micromotion

Locking mechanism

Conformity

Cam & post

Common to both prostheses:

PS specific:

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%

PS knees

Long-term results

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%

Ritter, 2001 AGC 11 -- 99%

CR knees

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

The PCL in TKR: to preserve or to cut ?? - Unimololdweb.unimol.it/unimolise/allegati/54074/Giron.pdf · The PCL in TKR: to preserve or to cut ?? Francesco Giron ... Mobile MPa Neutral

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