Muscles producing movement of the knee joint

The main movement of the knee joint is flexion and extension. With the knee in a semiflexed position and the foot off the ground, there is, in addition, medial and lateral rotation of the tibia with respect to the femur. If the feet are on the ground when the knees are flexed, the rotation at the knee joint is taken up by the femur, which rotates about a vertical axis, running approximately through the intercondylar eminence. This allows the upper part of the femur to move from side to side as in moving along sideways from one seat to another.

The movement between the patella and the pattelar surface of the femur must also be taken into account when considering the movements of the knee.