Elbow & Common Disorders of the Elbow
The elbow joint acts as both a hinge and a swivel, providing a stable link for lifting, pushing, or gripping and for positioning the hand in space. The hinge is formed by the humeroulnar (trochleoulnar) and humeroradial (capitelloradial) articulations at the cubital joint. The humeroulnar is the principal joint, and the swivel is formed by the proximal radioulnar joint. These three joints share a common synovial cavity.
Stability of the elbow depends upon congruity of the articulating bones, anterior capsule, ligaments, and surrounding muscles.
The common flexor tendon of the elbow (pronator teres, flexor carpi radialis, palmaris longus, flexor digitorum superficialis, and flexor carpi ulnaris) takes origin from the medial epicondyle and supracondylar ridge of the humerus. The common extensor tendon (extensor carpi radialis longus and brevis, brachioradialis, extensor digitorum communis, extensor carpi ulnaris, and anconeus) originates from the lateral epicondyle, supracondylar ridge, and distal humerus. The biceps tendon crosses the elbow joint to insert into the radial tuberosity.
The ulnar nerve runs in a bony groove behind the medial epicondyle. The olecranon bursa, a subcutaneous cushion at the olecranon process, is synovially lined but is anatomically separate from the elbow joint
Full elbow extension, the neutral (anatomic) position, is defined as 0°.
With the elbow in full extension, there is normally a slight valgus angulation of the forearm with respect to the humerus. This angulation, referred to as the carrying angle, is due to the oblique shape of the trochlea and is normally ~5° to 10° in men and ~10° to 25° in women. This angle allows the forearms to clear the hips during the normal arm swing of ambulation and is important for carrying objects at the side, without requiring shoulder abduction. Excessive deviation of the forearm away from the body is referred to as cubitus valgus, and deviation of the forearm toward the body is called cubitus varus.
Normal elbow flexion is from 0° to 160°. Any deficit in full extension is referred to as a flexion contracture. The brachialis, biceps, and brachioradialis are the primary flexors of the elbow, and the large, powerful triceps and small, relatively weak anconeus are the extensors. A minimum total arc of elbow flexion–extension of ~100° is required for normal activities.
Elbow pain is commonly caused by a number of conditions that include periarticular (e.g. Olecranon bursitis, lateral and medial epicondylitis), articular (e.g. arthritis, gout and pseudogout, rheumatoid, psoriatic; osteoarthritis), bone (fracture and dislocation), or neurologic problems, (cubital tunnel syndrome, radiculopathy).
Evaluation of elbow pain focuses on answering three important questions: Is there evidence of major trauma or injury? Can symptoms and signs be adequately explained by a local problem confined to the elbow? Is there evidence of a more generalized articular process, of which the elbow is only a part, or a neurologic process with elbow symptoms referred from another site?
A helpful mnemonic for characterizing pain in almost any site OPQRST: O = onset, P = precipitating (and ameliorating) factors, Q = quality, R = radiation, S = severity, T = timing.
- The extensor surface of the elbow is one of the most common sites for rheumatoid nodules. It is also one of the most common sites of cutaneous psoriasis.
- Musculoskeletal complaints in patients with psoriasis raise the question of whether the patient might have psoriatic arthritis.
- The most clinically urgent problem involving the bursa is septic olecranon bursitis.
- Elbow joint swelling in the context of acute injury or major trauma should prompt a comprehensive orthopedic evaluation for fracture or dislocation
- Patients with lateral epicondylitis (tennis elbow), usually complain of localized pain and tenderness at the lateral epicondyle, often accompanied by a mild aching discomfort in the proximal forearm.
- Medial epicondylitis (golfer’s elbow) is far less common than lateral epicondylitis. Like tennis elbow, it also is not primarily an elbow problem; it relates instead to an overuse syndrome from repetitive strain of the common flexor tendon involved in both forearm pronation and wrist flexion.
- Cubital tunnel syndrome is due to entrapment of the ulnar nerve in its groove behind the medial epicondyle. It is characterized by medial elbow pain, paresthesia along the ulnar aspect of the forearm into the ring and little fingers.