To correct deformities outside the knee joint without causing instability during a total knee replacement, the surgeon must consider both the shape of the bones and the proper alignment of the mechanical axis. The knee should be stabilized in a neutral horizontal or perpendicular joint line by aligning the prosthetic femur and tibia normally. This can be achieved by adjusting the resection of the medial femoral condyle or lateral tibial plateau to create an horizontal joint line in extension.

1. How to correct extraarticular deformity without causing instabilty ? Jean-Louis BRIARD

3. Consider shape of the bones + + (reference to the mechanical axis)