Abstract
Tennis elbow (also known as lateral epicondylitis) is caused by repetitive microtrauma to the extensor tendons of the forearm. The pathophysiology of tennis elbow initially involves microtearing at the origin of the extensor carpi radialis and extensor carpi ulnaris. Secondary inflammation may become chronic as a result of continued overuse or misuse of the extensors of the forearm. Coexistent bursitis, arthritis, or gout may perpetuate the pain and disability of tennis elbow.
The most common nidus of pain from tennis elbow is the bony origin of the extensor tendon of the extensor carpi radialis brevis at the anterior facet of the lateral epicondyle. Less commonly, tennis elbow pain originates from the origin of the extensor carpi radialis longus at the supracondylar crest; rarely, it originates more distally, at the point where the extensor carpi radialis brevis overlies the radial head. Radial tunnel syndrome and, occasionally, C6-7 radiculopathy can mimic tennis elbow.
Keywords
tennis elbow, lateral epicondylitis, radial nerve entrapment, radial tunnel syndrome, ultrasound guided injection, nonsteroidal antiinflammatory drugs, diagnostic ultrasonography, tennis elbow test
ICD-10 CODE M77.10
The Clinical Syndrome
Tennis elbow (also known as lateral epicondylitis) is caused by repetitive microtrauma to the extensor tendons of the forearm. The pathophysiology of tennis elbow initially involves microtearing at the origin of the extensor carpi radialis and extensor carpi ulnaris. Secondary inflammation may become chronic as a result of continued overuse or misuse of the extensors of the forearm. Coexistent bursitis, arthritis, or gout may perpetuate the pain and disability of tennis elbow.
The most common nidus of pain from tennis elbow is the bony origin of the extensor tendon of the extensor carpi radialis brevis at the anterior facet of the lateral epicondyle. Less commonly, tennis elbow pain originates from the origin of the extensor carpi radialis longus at the supracondylar crest; rarely, it originates more distally, at the point where the extensor carpi radialis brevis overlies the radial head. The olecranon bursa lies in the posterior aspect of the elbow joint and may also become inflamed (bursitis) as a result of direct trauma to the joint or its overuse. Other bursae susceptible to the development of bursitis lie between the insertion of the biceps and the head of the radius, as well as in the antecubital and cubital areas.
Tennis elbow occurs in individuals engaged in repetitive activities such as hand grasping (e.g., shaking hands) or high-torque wrist turning (e.g., scooping ice cream) ( Fig. 38.1 ). Tennis players develop tennis elbow by two different mechanisms: (1) increased pressure grip strain as a result of playing with a too heavy racket, and (2) making backhand shots with a leading shoulder and elbow rather than keeping the shoulder and elbow parallel to the net. Other racket sports players are also susceptible to the development of tennis elbow.
Signs and Symptoms
The pain of tennis elbow is localized to the region of the lateral epicondyle. This pain is constant and is made worse with active contraction of the wrist. Patients note the inability to hold a coffee cup or use a hammer. Sleep disturbance is common. On physical examination, tenderness is elicited along the extensor tendons at or just below the lateral epicondyle. Many patients with tennis elbow exhibit a bandlike thickening within the affected extensor tendons. Elbow range of motion is normal, but grip strength on the affected side is diminished. Patients with tennis elbow have a positive tennis elbow test result. This test is performed by stabilizing the patient’s forearm and then having the patient clench his or her fist and actively extend the wrist. The examiner then attempts to force the wrist into flexion ( Fig. 38.2 ). Sudden severe pain is highly suggestive of tennis elbow.
Testing
Electromyography can help distinguish cervical radiculopathy and radial tunnel syndrome from tennis elbow. Plain radiographs should be obtained in all patients who present with elbow pain to rule out joint mice and other occult bony disease. Ultrasound imaging will help quantify the extent of tendinopathy and identify other occult causes of the patient’s pain symptomatology ( Fig. 38.3 ). Based on the patient’s clinical presentation, additional testing may be warranted, including a complete blood count, uric acid level, erythrocyte sedimentation rate, and antinuclear antibody testing. Magnetic resonance imaging of the elbow is indicated if joint instability is suspected or if the symptoms of tennis elbow persist ( Fig. 38.4 ). The injection technique ( Fig. 38.5 ) described later serves as both a diagnostic and a therapeutic maneuver.
