knee joint

The knee joint is a synovial joint that connects three bones; the femur, tibia and patella. It is a complex hinge joint composed of two articulations; the tibiofemoral joint and patellofemoral joint. The tibiofemoral joint is an articulation between the tibia and the femur, while the patellofemoral joint is an articulation between the patella and the femur.
The knee joint is the largest and arguably the most stressed joint in the body. The arrangement of the bones in the joint provides a fulcrum that translates the actions of the flexor and extensor muscles of the knee. The arrangement of the extracapsular and intracapsular and ligaments, as well as extensions of muscles that cross the joint, provide the much needed stability that counters the considerable biomechanical stress brought upon the joint. As a hinged joint, the knee joint mostly allows movement along one axis in terms of flexion and extension of the knee in the sagittal plane. It also allows slight medial rotation during flexion and the last stage of extension of the knee, as well as lateral rotation when “unlocking” the knee.