The effect of trochlear design on patellofemoral shear and compressive forces in total knee arthroplasty.

Biomechanical testing was performed on 5 cadaveric knees to evaluate the effect of patellofemoral design on shear and compressive force at the patellar component-bone interface. Three patellofemoral designs with identical tibiofemoral articular surfaces were tested. The knees were tested under dynamic loading conditions from 0 degree to 100 degrees flexion. A transducer that measured 3 orthogonal force components was mounted between the patellar component and the patella. The combination of an oval dome patella with a 2-mm deeper trochlear groove and associated increased femoral resection was compared with a biconcave patella with standard trochlea and normal femoral resection. Alignment of the trochlear groove in 7 degrees valgus (anatomic) decreased medial-lateral shear by 10% to symmetric trochlear groove alignment.