The knee joint joins the thigh with the leg and consists of two articulations: one between the femur and tibia, and one between the femur and patella. It is the largest and most complicated joint in the human body. The knee is a mobile trocho-ginglymus (i.e. a pivotal hinge joint), which permits flexion and extension as well as a slight medial and lateral rotation[WP,unvetted]. [ http://en.wikipedia.org/wiki/Knee ]