BIOMECHANICS OF THE ELBOW AND FOREARM

The elbow joint functions as a link between the shoulder and wrist providing an exceptional amount of stability and motion. The elbow joint should not be considered a simple hinge joint; rather there are important out-of-plane motions that affect implant design and surgical reconstruction of the elbow. Forearm rotation, which occurs as the radius wraps around the ulna, guided by the soft tissues at the wrist and elbow joints, also contributes to upper extremity mobility. Force transmission in the forearm is a complex interaction of the radius, ulna, and interosseous membrane. Forces at the wrist affect the transmission of force through the forearm to the elbow joint. During some activities, forces at the elbow joint can reach several times body weight. These motion, stability, and force interactions allow for the forearm's function. It should be recognized that an event at the elbow joint affects the forearm and the wrist, and conversely injury or disease at the wrist joint can affect the elbow.