What causes elbow tendonitis, particularly in individuals between the ages of 30 and 50 who may have underlying conditions such as rheumatoid arthritis or gout?

Elbow Tendonitis Etiology

Elbow tendonitis is fundamentally caused by repetitive overuse leading to degenerative tendinopathy (tendinosis), not inflammation, despite the common misnomer "tendonitis." 1, 2

Primary Mechanism

The condition develops through repetitive loading and overuse that causes microscopic tears and failed tendon healing at the tendon-bone junction, resulting in collagen fiber disorientation and structural weakness rather than an inflammatory process. 2, 3

• The pathoanatomy is specifically "angiofibroblastic tendinosis"—a degenerative, non-inflammatory process affecting the extensor carpi radialis brevis-extensor digitorum communis complex laterally. 3
• Tensile overload disrupts normal collagen alignment and production, leading to progressive structural weakness. 2

Specific Activities and Risk Factors

Repetitive wrist extension, radial deviation, and forearm supination are the primary causative movements. 4

• Activities requiring repetitive wrist flexion and extension are the main culprits, including racquet sports (hence "tennis elbow") and occupational tasks. 1, 4
• Lateral epicondylosis is 7-10 times more common than medial epicondylosis and involves the dominant arm 75% of the time. 1
• The condition affects men and women equally and is most common after age 40. 1, 4

Contributing Biomechanical Factors

Improper technique, equipment issues, and muscle imbalances contribute to development beyond simple overuse. 2

• The osteotendinous junction where tendon inserts into bone is particularly vulnerable to overuse injury. 2
• Gradual, increasing load-related stress coinciding with increased activity intensity is the typical pattern. 2

Age-Related Considerations

For the 30-50 age group specifically mentioned in your question, the peak incidence occurs after age 40, placing this demographic at highest risk. 1, 4

Underlying Conditions

Rheumatoid arthritis and gout can cause elbow pain but represent distinct pathologies from overuse tendinopathy. 5

• When multiple symptomatic tendons are present, this should alert you to evaluate for rheumatic disease rather than simple overuse tendinopathy. 1
• Rheumatoid arthritis causes inflammatory arthritis of the elbow joint itself, not the degenerative tendinopathy seen in tennis elbow. 5
• These conditions require different treatment approaches focused on the underlying systemic disease rather than local tendon rehabilitation. 5

Important Clinical Distinction

The term "epicondylitis" is a misnomer—while acute inflammatory tendinopathies exist, most patients presenting to primary care have chronic degenerative conditions that should be labeled "tendinosis" or "tendinopathy." 2

• By the time patients present with prolonged symptoms, acute inflammation has typically subsided and been replaced by collagen degeneration. 1
• This distinction is critical because anti-inflammatory treatments may provide symptomatic relief but do not address the underlying degenerative pathology. 2

Medication-Related Etiology

Fluoroquinolone antibiotics increase the risk of tendinopathy, with an adjusted relative risk of 3.7 for Achilles tendinitis and 1.3 for other tendinitis types. 1

• Risk is highest in patients over 60 years, especially with concurrent corticosteroid use (relative risk 6.2). 1
• Symptoms typically occur within one week of fluoroquinolone exposure (median 6 days). 1