The FEMUR POINT OF ROTATION can be selected as which of the following?

• A. Knee center
• B. Posterior medial condyle
• C. Both knee center or posterior medial condyle
• D. Ankle center

Answer: (C)

Think about how the femur’s rotation during knee movement is modeled. You need a reference point on the femur that serves as the anchor for its hinge-like rotation. Two common, valid choices are the knee center and the posterior medial condyle. The knee center is a convenient, overall reference that represents the joint’s central location, while the posterior medial condyle is a reliable anatomical landmark that lines up with the posterior aspect of the femur where the knee’s flexion-extension motion is effectively guided. Depending on the measurement method or imaging data you have, either can be used to define the femur’s point of rotation. The ankle center isn’t appropriate because it lies far from the knee and does not accurately reflect the femur’s rotation. Therefore, selecting either the knee center or the posterior medial condyle is acceptable.