N°006 - July / August 2020
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Mechanical alignment alternatives: From anatomical to kinematic alignment in total knee arthroplasty
By Sébastien Lustig*, Elliot Sappey Marinier*, Frederic Sailhan**, Emmanuel Marchetti***, Pascal Duffiet****, David Benzaquen*****, Charles Rivière****** in category SURGICAL TECHNIQUE
* CHU Lyon Croix Rousse, Lyon, - ** Clinique ARAGO, Paris, - *** Médipôle, Lyon Villeurbanne **** Clinique DOMONT, - *****Clinique de l’UNION, Toulouse - ******MSK Lab, Imperial College London
Traditionally for the last 4 decades, the best outcome for a total knee arthroplasty (TKA) was seen with the mechanical alignment (MA) concept aiming for a neutral leg axis (180° mechanical femorotibial angle). At the same time, the MA technique aligns the femoral and tibial component frontally in 90° to the mechanical axis in order to create a femorotibial joint line perpendicular to the neutral mechanical axis. In the axial plane the femur component is aligned parallel to the transepicondylar axis, which is thought to be the best compromise for the flexion/extension axis of the native knee. For the axial alignment of the tibia component most surgeons used the tibia tubercle as the functional landmark to realign the MA TKA to the extensor mechanism.
The concept of MA was based on the assumption, that correcting all knees to neutral mechanical alignment, reduces the knee adduction moment and the forces on the implant, distributing them more evenly between the medial and lateral femorotibial compartments and thereby minimising the potential for accelerated polyethylene wear or early loosening. The MA concept systematically creates a knee implant that is supposedly ‘biomechanically advantageous’ but does not allow the surgeon to address the patient’s specific...
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