ROTATING PLATFORM AND PATELLOFEMORAL

JOINT

Guy BELLIER & Patrick DJIAN PARIS

PLATEAU MOBILE ET ARTICULATION

FEMORO-PATELLAIRE

Guy BELLIER

LAT

MED

LAT

PATHOGENIE DES ACCIDENTS ROTULIENS

Alignement femoro-tibial incorrectComposants inadaptés (trochlée)Mauvaise coupe rotulienneMauvaise adaptation entre les composants femoral & tibialHyper-rotation interne du plateau tibial

PATELLOFEMORALJOINT KINEMATICS

AFTER TKA

PATELLO-FEMORAL BIOMECHANICS

EXPERIMENTAL STUDIES

AUBRIOT (Sofcot 1993 ) : GOLDBERG (1991) Total Condylar on cadaver knees

from 0° to 75° :no increase of patellarstress,whatever the rotation of the tibial componentfrom 75° to 115° : increase of patellarstress with internal rotation of tibial component

EXPERIMENTAL STUDIES

CHEW : Clin Orthop 19973 different types TKA on cadaver knees

progressive knee flexion increases internalrotation of the tibia (normal knee and TKA)excessive internal rotation of the tibial component may be forced the tibia into a lateral position thus lateralizing the tibial tubercle.

EXPERIMENTAL STUDIES

LEMAIRE : Esska J. 1997

20 cadaver kneesdifferential anglea compromise between 2 requirements

optimal bone coveragesatisfactory patellofemoral tracking

SYMMETRICAL TIBIAL TRAY : 10° ASYMMETRICAL TIBIAL TRAY : 19°

LATMED

EXPERIMENTAL STUDIES

LEMAIRE : Esska J. 1997

Differential anglesymmetrical tibial tray : 10°asymmetrical tibial tray :19°

THE MOBILE POLYETHYLENE

COMPONENT ENSURES AUTOMATIC

ALIGNMENT OF THE EXTENSOR

APPARATUS WHATEVER THE

POSITION OF THE KNEE

EXPERIMENTAL STUDIES

MATSUDA & WHITESIDEJ Arthroplasty 19997 cadaver knees,fixed and mobile tibial componentsMalrotation of the tibial tray with therotationally meniscal bearing does not affect knee kinematics

EXPERIMENTAL STUDIES

The results of this study suggest that thehighly conforming rotating platform offers thebest compromise to achieve near-normalkinematics,acceptable range of motion and low contact stress

CLINICAL STUDIES

Patellar dislocation following TKR

Merkow,Soudry & Insall : JBJS 198512 LATERAL PATELLAR DISLOCATIONS (11 patients)The cause of dislocation was malrotation of the tibial component : 3 knees

ROTATIONAL MALALIGNMENT : PATELLARDISLOCATION

ROTATIONAL MALALIGNMENT :

PATELLAR DISLOCATION

INSALL 1985

PATELLAR COMPLICATIONS IN TKA

BOOTH RE.THE KNEE (Scott WN) 1994Benefits of floating tibial trials to furtherasses proper rotatory alignment

PATELLAR COMPONENT IN TKA

Michael A.KELLYCurrent concepts in primary and revisionTKA 1996Rotational alignment of the tibial component is largely subjective and left to surgicaldiscretionVisual orientation and a desire to seekcoverage of the tibia with the tibial component may lead to internal rotation of the component

THE PATELLA IN TKA

Dennis C. BLACKBURN and Kelly G. VINCESeminars in Arthroplasty,October 1999Maltracking is the root of all patellarproblemsThe tibial component should be alignedwith the extensor mechanism

THE PATELLA IN TKA

BLACKBURN & VINCE 1999Anything which internally rotates the tibial component favors maltracking,poly wear and dislocation

BRIARD & HUNGERFORD J Arthro. 1989Poor exposure of the proximal tibia

GOOD EXPOSURE : TIBIAL TUBERCLE OSTEOTOMY

A metal-backed,rotating-bearing patellar prosthesis

to Lower Contact Stress.An 11-year clinical study

Fred BUECHEL : Clin Orthop 1989

371 RP LCS knees0.19 % patellofemoral dislocation

F.BUECHEL

Rotating metal-backed patellarcomponent in TKA

Louis R. JORDAN,Peter A. KEBLISH: AAOS 19931939 LCS TKAFollow-up : 11 y.6 (0.3 %) patellar dislocation

Malrotation causingpatellofemoral complications

after TKA

R.A. BERGER & al : Clin Orthop 1998CT scan study

30 patients with isolated PF complications after TKA20 patients with well functioning TKA

23°

AXIAL CT IMAGE THROUGH THE TIBIAL COMPONENT

ATT

ROTATION INTERNE COMBINEE FEMUR + TIBIA

INTERNAL COMPONENT ROTATION MAY BE THE

PREDOMINANT CAUSE OF PF COMPLICATIONS IN PATIENTS

WITH NORMAL AXIAL ALIGNMENT

In the 30 patients with PF complications,the combined excessive internal component rotation is directly

correlated with the severity of thecomplication (normal axial alignment)

lateral tracking : -1° to -4°Subluxation : -3° to -8°Dislocation : -7° to -16°Prosthesis failure : -8° to -17°

This study validatesthe epicondylar axisand the tibial tubercle

as excellent landmarks to asses rotation

Femoral component should bealigned to

the epicondylar axisand tibial component should

be aligned18° from the tibial tubercle

18°

THE MOBILE POLYETHYLENE COMPONENT ENSURES

AUTOMATIC ALIGNMENT OF THE EXTENSOR APPARATUS

WHATEVER THE POSITION OF THE KNEE