What is the root cause of tennis elbow?

Root Cause of Tennis Elbow

Tennis elbow (lateral epicondylitis) is primarily caused by overuse leading to tendon degeneration rather than inflammation, resulting in a degenerative tendinopathy at the origin of the forearm extensor muscles. 1, 2

Pathophysiology

• Tennis elbow is fundamentally a degenerative tendinopathy, not an inflammatory condition, despite the common misnomer "tendonitis" 1
• The condition affects the origin of the forearm extensor muscle mass, particularly the extensor carpi radialis brevis-extensor digitorum communis complex 3
• Repetitive loading and overuse lead to microscopic tears and failed tendon healing at the lateral epicondyle 1, 3
• The pathoanatomy is characterized by "angiofibroblastic tendinosis" - degenerative changes in the tendon tissue rather than active inflammation 3

Contributing Factors

• Repetitive motions during athletic activities (particularly racquet sports) or occupational tasks are the primary triggers 4
• The condition develops through gradual, increasing load-related localized pain coinciding with increased activity 1
• Biomechanical factors such as improper technique, equipment issues, or muscle imbalances can contribute to the development of tennis elbow 2
• Tensile overload of the tendon disrupts normal collagen alignment and production, leading to structural weakness 2

Anatomical Considerations

• Tennis elbow affects the osteotendinous junction where the tendon inserts into bone, which is particularly vulnerable to overuse injury 1
• The tendon structure (composed of densely arranged collagen fibers, elastin, and proteoglycans) becomes disrupted with repeated stress 1
• The condition primarily involves the lateral epicondyle, though similar pathology can affect the medial epicondyle (golfer's elbow) 5

Common Misconceptions

• The term "epicondylitis" incorrectly implies inflammation, when the condition is primarily degenerative in nature 1
• While acute inflammatory tendinopathies exist, most cases seen in primary care represent chronic degenerative conditions that should be labeled as "tendinosis" or "tendinopathy" 1
• Anti-inflammatory treatments may provide symptomatic relief but do not address the underlying degenerative pathology 2

Clinical Implications

• Understanding the degenerative nature of tennis elbow explains why treatments focused solely on reducing inflammation often fail to provide long-term relief 2
• Effective treatment must address the underlying tendon degeneration through controlled loading and progressive strengthening 2
• Eccentric strengthening exercises are particularly beneficial as they promote tendon healing and guide normal alignment of newly formed collagen fibers 2
• Corticosteroid injections, while providing short-term relief, may actually inhibit healing and reduce tendon tensile strength 2

Diagnostic Considerations

• Diagnosis is primarily clinical, based on lateral elbow pain during twisting and gripping activities 6
• Tenderness at the lateral epicondyle, exacerbated by stress testing of the forearm extensors, is a hallmark finding 6
• Imaging is typically not necessary for diagnosis but may help rule out other causes of elbow pain 1