The three bones that comprise the knee joint are the femur (thigh bone), the tibia (shinbone) and the patella (kneecap). The knee may be described as a modified hinge joint, similar to the hinge on a door. However, the knee not only bends back and forth like a hinge, it has a complex rotational component that occurs with flexion and extension of the knee.
The knee is a major weight-bearing joint that is held together by muscles, ligaments and other important soft tissues. Cartilage is the material inside the joint that provides shock absorption to the knee during weight-bearing activities such as walking or stair climbing.
The knee can be divided into three compartments:
- the medial compartment
- the lateral compartment
- the patello-femoral compartment