Elbow Dislocation

Excerpt

The elbow is among the most common large joints to dislocate. Dislocations may be isolated, involve damage to static supportive structures of the elbow, and may even cause fractures about the elbow. Because of this, it is important to recognize elbow dislocations and know the appropriate management to avoid any complications.

Simply put, the elbow is the articulation between the distal humerus with the proximal ulna and radius. The distal humerus contains the trochlea medially and capitulum laterally. Three separate articulations comprise the elbow. The medial aspect of the elbow includes the ulnotrochlear joint, which is primarily responsible for flexion and extension. The lateral radiocapitellar joint and the proximal radioulnar joint are mainly responsible for pronation and supination. This anatomy creates a combination of a hinge joint and a pivot joint.

The anatomy of the ulna allows two articulations and serves as an area of attachment for many structures. The greater sigmoid notch of the ulna creates the ulnotrochlear joint, and the lesser sigmoid notch creates the proximal radioulnar joint. The proximal anterior surface of the ulna also contains the coronoid process. The anteromedial facet (called the sublime tubercle) creates the insertion point for the medial collateral ligament, specifically, the anterior bundle. The anterior band of the medial collateral ligament is a basic structure for valgus stability of the elbow.

The elbow is generally stable due to the congruity articular surfaces. It is further supported by static supporting structures, including the collateral ligaments on the medial and lateral side of the elbow and the joint capsule. Dynamic stabilizers of the joints are composed of the surrounding musculature.

The vascular anatomy of the elbow is composed of a few structures. The brachial artery is a central component of the anterior elbow and eventually divides into the radial and ulnar artery in the proximal forearm. The radial and ulnar artery, along with the brachial and the deep brachial artery, comprise an intricate anastomosis of vessels around the elbow, including the radial and ulnar collateral arteries and the radial and ulnar recurrent arteries.

There are many nerves that exist around the elbow, and whose function can be compromised by an elbow dislocation. The radial nerve runs in the posterior compartment of the arm in the radial groove of the humerus and wraps laterally to its position near the elbow, where it is anterior to the lateral epicondyle. It then divides into a superficial and deep branch, the deep branch giving rise to the posterior interosseus nerve after it has passed through the heads of the supinator muscle. The median nerve runs in the medial bicipital groove of the arm along with the brachial artery, passing over the brachial artery and under the bicipital aponeurosis near the elbow, staying medial to the brachial artery. The anterior interosseus nerve is a terminal branch of the median nerve after it passes through the heads of the pronator teres, giving rise to the motor function a majority of the deep flexor compartment of the forearm. The ulnar nerve lies in the medial arm, and near the elbow, passes just posterior to the medial epicondyle of the humerus.