The elbow is a complex hinge joint, which allows flexion, extension and rotation of forearm. It is formed by the articulation between the bottom end of the humerus (the arm bone) and the ulna and radius (the two forearm bones). The elbow joint complex has three articulations. The first being the hinge joint formed between the humerus and the ulna called the humeroulnar joint, which allows us to bend and straighten our elbows. The second is the humeroradial joint between the radius and humerus, which again allows flexion and extension but is also involved in the more complex motion of turning the hand over so the palm faces up or down. This movement of the forearm is called supination (palm up) and pronation (palm down). The third is a pivot joint formed by the radius and ulna and is called the proximal radioulna joint and is essential for forearm rotation.
An extensive network of ligaments surrounding the joint capsule helps the elbow joint maintain its stability and resist mechanical stresses. The radial and ulnar collateral ligaments connect and maintain the position of the radius and ulna relative to the epicondyles of the humerus. The annular ligament of the elbow extends from the ulna around the head of the radius to hold the bones of the lower arm together. These ligaments allow for movement and stretching of the elbow while resisting dislocation of the bones.
The complex anatomy of elbow makes it vulnerable to overuse injuries causing micro-tears of the muscles that arise from the sides of the joint. This can lead to pain on the outside of the elbow (lateral epicondylitis or tennis elbow) or the inside of the elbow (medial epicondylitis or golfer’s elbow).
The joint is commonly injured when people fall on their outstretched hand or directly onto the tip of the elbow (the olecranon). In children the elbow tends to break just above the growing area at the bottom of the humerus, a so-called supracondylar fracture. Adults can break the bottom end of the arm bone, the head or neck of the radius bone or they can partially or fully dislocate the joint.
Common Elbow conditions:
- Tennis elbow
- Golfers elbow
- Locking or clicking elbow
- Distal biceps rupture
- Osteochondritis dessicans
- Posterior impingement
- Stiff elbow