Tennis elbow, also known as lateral epicondylitis, is an enthesopathy (attachment point disease) of the origin of the extensor carpi radialis brevis on the lateral epicondyle. It causes pain and tenderness over the lateral epicondyle. Tennis elbow is idiopathic, meaning its precise cause is unknown. It likely involves tendinosis, an overuse injury of the local tendon. It is typically associated with work or sports – classically racquet sports (including paddle sports) – but many people with the condition are not participants in these activities. The diagnosis is based on the symptoms and examination. Medical imaging is not commonly used. Untreated enthesopathy usually resolves in 1–2 years. Treating the symptoms and pain involves medications such as NSAIDs or acetaminophen, a wrist brace, or a strap over the upper forearm. Corticosteroid injections as treatment are not common.
Signs and symptoms Patients typically feel pain or burning around the outer part of the elbow (lateral epicondyle of the humerus), which can move down the forearm and sometimes up to the upper arm. The pain is worsened by activities that involve wrist extension, such as gripping objects. Pain intensity varies from mild to severe and can be intermittent or constant, significantly impacting daily life. Patients also commonly report grip weakness and difficulty lifting.
Terminology The term "tennis elbow" is widely used (although informal), but the condition affects non-tennis players. In the 21st century, the growth of pickleball participation led to the term, pickleball elbow. Historically, the medical term "lateral epicondylitis" was most commonly used for the condition, but "itis" implies inflammation, and the condition is not typically an inflammation. It is also referred to as enthesopathy of the extensor carpi radialis origin. Because histological findings reveal noninflammatory tissue, the terms "lateral elbow tendinopathy" and "tendinosis" are used clinically. In 2019, a group of international experts suggested that "lateral elbow tendinopathy" was the most appropriate terminology, although an injury at an attachment point (or enthesia) is typically called an enthesopathy.
Causes
The exact cause of lateral epicondylitis remains unclear. However, it is often linked to repetitive microtrauma resulting from excessive gripping, wrist extension, radial deviation, and/or forearm supination. Traditionally, people have speculated that tennis elbow is a type of repetitive strain injury resulting from tendon overuse and failed healing of the tendon, but there is no evidence of injury or repair, and misinterpretation of painful activities as a source of damage is common.
Pathophysiology The extensor carpi radialis brevis (ECRB) is the most commonly affected muscle in lateral epicondylitis, along with other extensor carpal muscles. Due to its unique origin, the ECRB tendon is prone to abrasion during elbow movements, leading to repetitive microtrauma, and interpretation that tennis elbow is a mechanical overuse injury. Lateral epicondylitis was initially considered an inflammatory process, although there is no clear evidence of inflammation. Therefore, the disorder is more appropriately referred to as tendinosis or tendinopopathy. Tendinosis is a degenerative condition involving fibroblasts, abnormal collagen, and increased blood vessels. Repetitive stress causes microtears, scar tissue formation, and biomechanical changes, with worsening symptoms over time.
Clinical evaluation
Physical examination Diagnosis is based on symptoms and clinical signs that are discrete and characteristic. For example, the extension of the elbow and flexion of the wrist causes outer elbow pain. The physical examination usually reveals marked tenderness at the origin of the extensor carpi radialis brevis muscle from the lateral epicondyle (extensor carpi radialis brevis origin). Pain may worsen with resisted wrist extension, middle finger extension, and forearm supination with an extended elbow, although normal elbow movement is often maintained, even in severe cases.
Medical imaging Medical imaging is not necessary or helpful. Radiographs (X-rays) may demonstrate calcification where the extensor muscles attach to the lateral epicondyle. Longitudinal sonogram of the lateral elbow displays thickening and heterogeneity of the common extensor tendon that is consistent with tendinosis, as the ultrasound reveals calcifications, intrasubstance tears, and marked irregularity of the lateral epicondyle. Although the term "epicondylitis" is frequently used to describe this disorder, most histopathologic findings of studies have displayed no evidence of an acute, or a chronic inflammatory process. Histologic studies have demonstrated that this condition is the result of tendon degeneration, which replaces normal tissue with a disorganized arrangement of collagen. Colour Doppler ultrasound reveals structural tendon changes, with vascularity and hypo-echoic areas that correspond to the areas of pain in the extensor origin. Table of Clinical classification of lateral epicondylitis phases.
Prevention Activity modification is the best way to prevent the occurrence of lateral epicondylitis. Prevention can include avoiding extreme end range motions in extension and flexion, limit repetitive hand and wrist motions, and modification of heavy lifting with extended arms. Lifestyle factors such as smoking, alcohol drinking, and dietary habits are known to influence the prognosis of various medical conditions. Smokers showed a higher chance of developing lateral epicondylitis compared to non-smokers. Current research indicates that alcohol intake is not significantly associated with lateral epicondylitis.
Treatment
Non-operative treatment There is no standard method for treating tennis elbow. Non-operative treatment resolves 90% of symptomatic lateral epicondylitis. Nonoperative care usually includes activity modification, physical therapy, non-steroidal anti-inflammatory medications, bracing, extracorporeal shock-wave therapy, and acupuncture. Modifying activity and avoiding overuse are key to treatment. Lifting with the palm up and avoiding palm-down movements can shift strain from the lateral to the medial epicondyle, easing pain. Following the RICE method (rest, ice, compression, elevation) can help relieve pain initially.
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