Lateral Elbow Tendinopathy (Tennis Elbow)

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Lateral Elbow Tendinopathy

Lateral Elbow Tendinopathy (LET), commonly known as tennis elbow or lateral epicondylitis, is a chronic overuse injury affecting the tendons of the lateral elbow. Recent research suggests that “epicondylitis” is a misnomer, as the condition more accurately represents chronic tendinosis. Microscopic examination has revealed angiofibroblastic degeneration rather than inflammation, indicating degenerative changes at the site of the tendon injury. Studies also highlight that the extensor carpi radialis brevis (ECRB) tendon is the primary site of involvement, making it a key structure in the pathophysiology of lateral elbow tendinopathy. Other terms for this condition include elbow tendinosis, elbow tendonitis, and lateral epicondylalgia.

Although often associated with tennis, only 5% to 10% of reported cases involve tennis players. The condition is more prevalent among manual laborers and individuals engaging in repetitive forearm activities. LET affects 1% to 3% of the adult population annually, occurs equally in both sexes and is most commonly seen in individuals in their 40s and 50s. It predominantly affects the dominant arm, reflecting the repetitive nature of activities that place stress on the extensor tendons of the forearm.

The mechanism of injury involves repetitive wrist motions that subject the muscles and tendons to rapid, forceful lengthening under load (eccentric contraction). This repetitive stress can lead to microtears in the tendon fibers, particularly in areas where the tissue is already vulnerable. Once the initial injury occurs, engaging in strenuous or exaggerated movements further exacerbates the condition by causing additional damage to the degenerative or disorganized tissue. This cycle of strain, damage, and attempted healing without sufficient recovery can perpetuate the condition, leading to chronic tendinopathy.

• Lateral elbow pain ranging from mild discomfort to severe, debilitating pain
• Severe cases may involve pain radiating down the posterior forearm
• Gradual, insidious onset, often without a specific triggering event
• Pain worsens with repetitive wrist or elbow activities (e.g., playing tennis, using tools like screwdrivers)
• Relief with rest, with symptoms diminishing when activity is reduced
• Severe pain can interfere with routine tasks (e.g., lifting objects, typing) and may disrupt sleep at night

• Localized tenderness just distal to and over the lateral epicondyle
• Pain exacerbated by active wrist extension and passive wrist flexion
• Positive Cozen’s test: Pain reproduced with resisted wrist extension while palpating the lateral epicondyle
• Positive Maudsley’s test: Pain elicited with resisted extension of the middle finger
• Positive Mill’s test: Pain triggered by passive wrist flexion with the elbow extended, stretching the extensor tendons

In most cases, clinical diagnosis based on history and physical examination is sufficient to initiate management. Imaging is usually unnecessary unless there are atypical findings or the condition is unresponsive to conservative treatment. However, diagnostic ultrasound can provide valuable insights by visualizing the extent of tendon thickening, degeneration, or tears. Additionally, plain radiography may help rule out bone or joint pathologies such as osteoarthritis or calcification around the lateral epicondyle, which could contribute to or mimic symptoms of lateral elbow tendinopathy.

The following are examples of “red flags” for patients presenting with elbow pain:

• History of a significant injury
• Severe pain
• Unrelenting pain
• Nocturnal pain or pain at rest
• Fever
• Deformity
• Large joint swelling
• Significant loss of range of motion
• Significant neurological impairment
• Severe tenderness on palpation or severe pain with any examination procedure

If any “red flags” are identified during history taking and clinical examination, referral for urgent medical evaluation and further investigation is warranted.

Differential Diagnosis of Lateral Elbow and Lateral Forearm Pain

Lateral Elbow Tendinopathy (LET)

• A degenerative condition of the extensor tendons, primarily affecting the extensor carpi radialis brevis (ECRB).
• Presents with pain and tenderness over the lateral epicondyle, often exacerbated by wrist extension and gripping activities. Cozen’s, Maudsley’s, Mill’s and resisted Supination tests cause pain directly over the lateral epicondyle.

Radial Tunnel Syndrome

• A neuropathic condition caused by compression of the posterior interosseous nerve as it passes through the radial tunnel.
• Symptoms include tenderness on palpation over the radial tunnel in the forearm, often mistaken for LET. Pain worsens with forearm rotation and elbow extension.  Resisted Supination, Cozen’s, and Maudsley’s tests cause pain in the proximal forearm in the region of the radial tunnel.

Radiohumeral Joint Dysfunction

• Involves mechanical issues within the radiohumeral joint, such as joint subluxation or arthropathy.
• Pain is localized over the joint, with stiffness and discomfort during forearm rotation (supination/pronation).

Lateral Collateral Ligament Sprain

• Caused by trauma or overuse, leading to instability and pain on the outer side of the elbow.
• Presents with tenderness over the ligament, aggravated by valgus stress testing of the elbow.

Myofascial Pain Syndrome

• Involves trigger points in muscles such as the supinator and brachioradialis, which refer pain to the lateral elbow or forearm.
• Palpation of these muscles may reproduce referred pain patterns, differentiating it from tendinopathy or nerve-related conditions.

Cervical Radiculopathy

• Caused by nerve root compression in the cervical spine, most often at C6 or C7, leading to radiating pain into the elbow and forearm.
• Symptoms may include numbness, tingling, or weakness along with the pain.