Lateral and medial epicondylitis are common causes of elbow pain and dysfunction. The appropriate management of epicondylitis is based on an understanding of the natural history as well as the anatomic, biochemical, and biomechanical principles underlying the condition. Management should always start with nonsurgical treatment, which is typically successful. Surgical treatment is reserved for recalcitrant and chronic cases that have exhausted nonoperative measures over a prolonged period of time. Treatment options are tailored to individual patients depending on professional and recreational demands and activities.

Lateral epicondylitis is the most common cause of elbow pain, and is noted to occur up to 10 times more commonly than medial epicondylitis, with an equal prevalence among male and female patients. Risk factors for developing lateral epicondylitis include advancing age, smoking, obesity, heavy lifting, and repetitive motion use. Although the diagnosis carries the eponym “tennis elbow,” tennis itself is actually the cause in very few cases of lateral epicondylitis. Nevertheless, it is common among tennis and other racquet sport players and affects 20% to 50%, with increased frequency noted among amateur or recreational players. The pathology predominantly involves the extensor carpi radialis brevis (ECRB) origin and occasionally the extensor digitorum communis (EDC).

Medial epicondylitis tends to affect patients in the fourth and fifth decades of life, usually affecting the dominant extremity, with an equal prevalence in males and females. Similar to lateral epicondylitis, medial epicondylitis results from repetitive stress in the setting of chronic inflammation. The pathology is found in the flexor pronator mass, particularly the pronator teres, flexor carpi radialis, palmaris longus, and sometimes the flexor carpi ulnaris (FCU) and flexor digitorum superficialis. Medial epicondylitis has earned the eponym “golfer’s elbow,” but can be seen in athletes and nonathletes alike.

Since epicondylitis was first described in the late 19th century, multiple theories have been proposed to explain the pathologic process. The current understanding is that epicondylitis represents microtearing of the medial or lateral tendons at their origin. A subsequent healing response is marred by vascular infiltration and changes in the normal structure of the musculotendinous junction. Nirschl and Pettrone (1979) described both the gross and histologic appearance of the pathologic process. They described the gross appearance of the tissue as a grayish amorphous substance. On a histologic level, the normal collagen architecture of the tissue is disrupted, with immature vascular invasion noted with a background surprisingly bereft of chronic and acute inflammatory cells. In the chronic setting, this leads to tendon degeneration that is described as “angiofibroblastic hyperplasia.” Stage 1 represents the early portion of the process, with acute inflammation and no architectural changes. Stage 2 has pathologic changes, with angiofibroblastic invasion, but integrity of the tendon is maintained. In stage 3, the structure of the tendon becomes altered; stage 4 marks the addition of fibrosis or calcification, as in a chronic setting. The term “tendonitis” is a confusing term that can be a misnomer in describing the pathologic process, especially in the chronic setting. Although inflammatory cells can be present, the pathologic specimen is not marked by a typical inflammatory presentation, but rather by an abundance of fibroblasts, vascular hyperplasia, and collagen lacking normal structure.

The accurate diagnosis of medial and lateral epicondylitis depends on a thorough, but focused, history and physical. Chronicity of symptoms, location of symptoms, type of pain, exacerbating activities, associated paresthesias, and muscle weakness must be addressed. History of sports or other resisted and repetitive activities that could explain the inciting event should be noted.

Medial epicondylitis is associated with pain along the medial epicondyle made worse with resisted forearm pronation or wrist flexion. Placing the elbow in an extended position provides maximal physiologic stretch to the tendons being assessed. Tenderness is more pronounced just distal and anterior to the medial epicondyle over the attachment of the flexor carpi radialis and pronator teres.

The ulnar nerve should be assessed both for subluxation and reproducible symptoms of paresthesia. A Tinel’s test or elbow flexion test may also be used to assess for ulnar nerve compression or irritation. The medial ulnar collateral ligament is evaluated with the moving valgus stress test and milking maneuver to rule it out as a source of medial-sided elbow pain.

Examination of the lateral elbow may elicit pain with palpation directly distal and slightly anterior to the epicondyle. Specific examination maneuvers include resisted wrist extension and resisted long finger extension. These maneuvers are typically more painful with the elbow extended than flexed. To rule out other causes of lateral elbow pain, the radiocapitellar joint should be palpated for arthritic pain and crepitus or snapping plica syndrome. The radial tunnel should also be palpated for tenderness.

In most cases of epicondylitis, plain radiographs are normal. Some patients have lateral epicondylar spurring or calcification. MRI scans are not necessary for diagnosis or treatment of epicondylitis. An MRI, however, may be used to rule out other pathology such as collateral ligament injury or plica if the diagnosis is unclear. Diagnostic ultrasound can show thickening and hypoechoic tendon origin or even small fluid collections.

Nonsurgical treatment is the mainstay of management of lateral and medial epicondylitis. A thorough review of randomized controlled trials regarding nonsurgical treatment of lateral epicondylitis demonstrates a high rate of long term success with nonsurgical treatment. Surgical treatment of medial and lateral epicondylitis is often reserved for recalcitrant cases, typically after 6 to 12 months of nonsurgical treatment. Less than 10% of patients with epicondylitis fail to improve with nonsurgical treatment and ultimately require surgical intervention.