Femoral rotational alignment using the tibial shaft axis in total knee arthroplasty

The capability of determining femoral component rotation by using a posterior femoral condyle resection made perpendicular to the longitudinal tibial shaft axis in posterior cruciate retaining total knee arthroplasty was evaluated. From 100 consecutive cases, 54 used the femoral posterior condyle axis and 46 used an extramedullary alignment rod based on the tibial shaft axis. Seventy-two percent of total knee arthroplasties using the posterior condyle axis required lateral release versus 28% using the tibial shaft axis. Patellar fracture occurred in 7% using the posterior condyle axis versus none using the tibial shaft axis. Two patients had both techniques in opposite knees. Using computed tomography, the posterior condyle axis method gave a posterior condyle angle of 5 degrees and 4 degrees compared with the transepicondylar axis, whereas the tibial shaft axis technique measured 0 degrees and 1 degree. The posterior condyle resection using the tibial shaft axis restores the anatomic patellofemoral relationships, minimizing patellofemoral complications.