The effect of femoral component external rotation on tibial rotation in total knee arthroplasty

External rotation of the femoral component has been suggested as a means of improving patellar tracking in total knee arthroplasty (TKA), but this procedure may also affect the tibiofemoral joint. TKA was performed on five cadaveric knee specimens. Each specimen was tested with femoral component external rotations of 0.0/spl deg/, 2.5/spl deg/ and 5.0/spl deg/, and 6 DOF kinematics were measured. In three of the specimens, the tibial external rotation angle increased with femoral component rotation. The magnitude of the change was always less than the magnitude of the femoral rotation. Soft tissue constraints appear to override kinematic constraints imposed by femoral component rotation.