Tennis Elbow (Lateral Epicondylitis)

Lateral epicondylitis anatomy showing inflammation at the lateral epicondyle and common extensor aponeurosis

Definition & Anatomy

Tennis elbow is a painful degenerative condition at the origin of the extensor carpi radialis brevis (ECRB) on the lateral epicondyle of the humerus. Despite the name, fewer than 5% of patients actually play tennis — it is far more common in manual workers (prevalence approaching 14.5% in the workforce), and arises from repetitive activities such as turning screws, using a wrench, gardening, or assembly line work.

Rosen's Emergency Medicine, 10th ed.
Roberts and Hedges' Clinical Procedures in Emergency Medicine

Pathophysiology

Although "epicondylitis" implies inflammation, histological examination consistently shows angiofibroblastic hyperplasia (also called angiofibroblastic tendinosis) — a degenerative process with a paucity of acute inflammatory cells. It is now better classified as a tendinopathy rather than true tendinitis.

Miller's Review of Orthopaedics, 9th ed.

Clinical Features

Symptoms:

Dull ache along the lateral aspect of the elbow, over the lateral epicondyle or radiohumeral joint
Pain exacerbated by grasping, twisting, wrist extension or supination

Examination findings:

Tenderness just distal (5–10 mm) to the lateral epicondyle, at the ECRB origin
Cozen's test (resisted wrist extension with forearm stabilized) — reproduces lateral epicondyle pain; sensitivity ~74%, poor specificity
Maudsley's test (resisted extension of the middle finger with elbow in extension) — reproduces pain at the lateral epicondyle; sensitivity ~54%, also poor specificity
Rosen's Emergency Medicine; Bailey and Love's Short Practice of Surgery, 28th ed.

Investigations

Plain radiographs: Usually normal; ~20% show tendon calcification or reactive exostosis at the epicondyle tip. Useful to exclude fractures in atypical or prolonged cases.
MRI: Characteristic findings described but not indicated emergently.
Differential diagnosis: Posterior interosseous nerve entrapment, radiohumeral bursitis, plica lesions, synovitis, chondromalacia, osteochondral defects.

Management

Conservative (first-line)

Measure	Notes
Activity modification	Avoid inciting activities
RICE + immobilization	Sling initially; analgesics
NSAIDs	Useful for analgesia, not anti-inflammatory effect per se
Physical therapy	Stretching, strengthening; superior to corticosteroid at 6 weeks and beyond
Counterforce brace	May reduce tendon load

Corticosteroid Injection

Provides short-term pain relief (superior to NSAIDs and physiotherapy for the first 6 weeks)
After 6 weeks, physical therapy becomes more effective
Do not inject directly into the tendon — corticosteroids weaken collagen
Avoid subcutaneous injection (risk of skin depigmentation/atrophy)
No clear long-term benefit — Miller's Review of Orthopaedics notes "no clear benefit from corticosteroid injection" overall

Emerging / Other Treatments

Platelet-rich plasma (PRP): Growing evidence; recent meta-analyses (2025) suggest PRP may outperform corticosteroid for longer-term outcomes in tendinopathy (PMID 40200209)
Extracorporeal shockwave therapy (ESWT): Systematic review (2024) suggests ESWT is at least comparable to corticosteroid injection for chronic lateral epicondylitis (PMID 39198038)
Dry needling: Updated meta-analysis (2024) supports therapeutic benefit (PMID 38484834)

Surgery

Reserved for recalcitrant cases failing prolonged conservative management (typically >6 months). Open and arthroscopic approaches show equivalent results. The procedure involves debridement/release of the ECRB origin.

Miller's Review of Orthopaedics, 9th ed.

Summary

Feature	Detail
Site	Lateral epicondyle (ECRB origin)
Pathology	Angiofibroblastic tendinosis (degenerative)
Key test	Cozen's / Maudsley's
First-line Rx	Activity modification, PT, NSAIDs
Injection	Short-term benefit only
Surgery	Last resort for recalcitrant cases

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