Biomechanics of the elbow joint

The biomechanics of the elbow joint is complex. The humerus, radius and ulna articulate with each other to allow positioning of the hand within a sphere defined by the shoulder movement and the length of the arm. This motion is controlled by the muscles that cross the joint and also act as secondary elbow joint stabilisers. Primary stability is provided by the osseous and ligamentous anatomy. The radial head and the coronoid process is important osseous stabilizers. The anterior part of the medial collateral ligament and the lateral collateral ligament is important ligamentous stabilizers. The joints in the upper extremity is often described as non-weightbearing, however the elbow is a load bearing joint with a biomechanical disadvantage of the long lever arm of forces applied through the hand, a relatively small joint surface area and short lever arm for ligaments and muscles to counterbalance. In this chapter we will focus on the clinical implications of the kinematics and biomechanics of the different parts of the elbow joint.