2022, Vol. 26 ›› Issue (6): 848-852
Finite element analysis of the effect of femoral component rotation on patellofemoral joint contact pressure in total knee arthroplasty
Patellofemoral joint complications are common after total knee arthroplasty. Rotational malalignment of the femoral component will affect the consistency of the patellofemoral joint, thus causing the changes of contact pressure and kinematics of the patellofemoral joint.
To study the changes of patellofemoral joint contact pressure during knee flexion when femoral component was placed at different rotation angles by means of finite element analysis.
The three-dimensional models of the knee joint were developed according to the CT and MRI scanning data of right knee of the volunteer. The femoral component was placed from 6° internal rotation to 9° external rotation (external rotation 3°, 6°, 9°, rotation 0°, internal rotation 3°, 6°) relative to the surgical transepicondylar axis (the line between the medial femoral condyle groove and the most prominent point of the lateral femoral condyle) in 3° increments, while tibial component was 0° rotated relative to the Akagi (the line between the medial edge of the patellar tendon and the center of the posterior cruciate ligament) during the total knee arthroplasty. The finite element models of the knee were established by meshing the three-dimensional models. The patellofemoral joint contact pressure of each knee joint model was obtained during the flexion.
(1) The patellofemoral joint contact pressure increased in all groups during the knee flexion. The contact pressure in the group of 3° external rotation femoral component was lower than that of 0° rotation group. The contact pressure of patellofemoral joint increased with the increase of external rotation degree of component when the degree of femoral component external rotation was greater than 3°. The contact pressures in the group of 3° internal rotation of femoral component and the group of 6° internal rotation were significantly higher than those of the other groups, and the highest was in the 6° internal group. (2) Results showed that during the total knee arthroplasty, 3° external rotation of femoral component relative to surgical transepicondylar axis may reduce the patellofemoral joint contact pressure, while excessive external rotation femoral component may lead to the increase of patellofemoral joint contact pressure. The internal rotation of femoral component should be avoided during the total knee arthroplasty. The imbalance of greater than 3° internal rotation may lead to the increase of patellofemoral joint contact pressure and increase the risk of prosthesis wear and knee pain.
knee, patellofemoral joint, total knee arthroplasty, finite element, femoral component, rotational alignment, contact pressure, biomechanics