Elbow Dislocations

Anatomy

The elbow is one of the most complex joints in the body, consisting of three articulations: ulnotrochlear, radiocapitellar, and proximal radioulnar. Elbow flexion/extension occurs mainly at the ulnohumeral and radiocapitellar articulation, whereas forearm pronation/supination involves the radiocapitellar and proximal radioulnar articulation. Normal range of motion (ROM) of the elbow is approximately 150° of flexion to 0° of extension, 90° of forearm pronation, and 90° of forearm supination. The elbow provides attachment sites for various muscle groups and ligaments. The primary stabilizers of the elbow are the ulnotrochlear articulation, the medial collateral ligament (MCL), and the lateral collateral ligament (LCL). The radial head and surrounding muscle bundles make up the secondary stabilizers of the elbow. The elbow joint is extremely congruent and stable due to the specific pattern in which each bone contacts [Page 415]and conforms to other structures within the elbow. Due to the configuration of these interactions, elbow fractures and/or dislocations need to be treated to near-anatomic alignment; otherwise, there can be a high complication rate. Complications include loss of ROM, structural instability, nerve palsies, and muscular weakness.

Clinical Evaluation

Elbow dislocations on physical examination may have an obvious deformity, diffuse joint pain and swelling, decreased or painful ROM, and crepitus. The normal anatomic triangle that is formed by the radial head, lateral epicondyle, and distal lateral tip of the olecranon process is disrupted with elbow dislocations. Any athlete who sustains trauma to the upper extremity and presents with any of those signs or symptoms should be evaluated for the possibility of an elbow fracture or dislocation. With such injuries, the examining physician must also assess the entire upper extremity for associated injuries. The force from a FOOSH injury can be transmitted from the hand up to the clavicle.

Several major nerves and vessels that traverse the elbow can be damaged or tethered. The radial nerve courses over the lateral epicondyle and radial head. Radial nerve function can be tested with middle-finger extension and sensation over the dorsal aspect of the thumb. The ulnar nerve sits within the ulnar groove between the medial epicondyle and olecranon and can be tested with finger abduction/adduction and sensation over the little finger. The median nerve courses over the anteromedial aspect of the distal humerus and elbow joint. Decreased sensation at the tips of the index or middle finger and/or decreased pinch strength with the thumb and index finger can indicate a median nerve injury. The brachial artery can also be injured as it travels with the median nerve across the elbow, after which it branches into the radial and ulnar arteries. Angiography may be needed if distal pulses are absent or diminished compared with the contralateral limb. Vascular injuries and forearm compartment syndrome are rare but have devastating consequences if missed. Any patient with neurovascular compromise should prompt more urgent intervention and reduction or be transferred to a facility capable of providing such treatment.

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