rotating platform and patellofemoral joint · 7 cadaver knees,fixed and mobile tibial components...
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PATHOGENIE DES ACCIDENTS ROTULIENS
Alignement femoro-tibial incorrectComposants inadaptés (trochlée)Mauvaise coupe rotulienneMauvaise adaptation entre les composants femoral & tibialHyper-rotation interne du plateau tibial
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
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
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
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
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
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
THE MOBILE POLYETHYLENE COMPONENT ENSURES
AUTOMATIC ALIGNMENT OF THE EXTENSOR APPARATUS
WHATEVER THE POSITION OF THE KNEE