ABSTRACT
The joints function to orient and direct motion and applied forces. A typical synovial joint is the union of two adjacent bones, whose ends are coated with a cushion of smooth, shock-absorbent hyaline cartilage. Normally, loads are transmitted through these cartilage coatings, without the adjacent bone surfaces ever touching. Joints bearing high loads are usually reinforced by cartilage discs or plates (e.g. between vertebrae in the back, in the knee, at the ulnar border of the wrist, or the the acromio-clavicular joint in the shoulder; Allan 1998).
