- Discussion:
- mechanical axis refers to the angle formed by a line drawn from the center of the femoral head to the medial tibial spine and a
line drawn from the medial tibial spine and the center of the ankle joint;
- this should not be confused w/ the wt bearing axis which runs from the center of the femoral head to the center of the ankle;
- w/ optimal alignment, the mechanism axis will form a straight line (overlapping the wt bearing axis)
- mechanical axis passes thru the three demensional anatomic center of knee;
- therefore, it also defines neutral alignment in every plane and is not subject to projectional variation;
- because hips are more widely separated than the knees and ankles, the mechanical axis is in 3 degrees of valgus from the true vertical
axis of body, which extends from center of gravity to the ground