Elbow Pain: Lateral Epicondylitis vs Radial Tunnel vs Cervical Radiculopathy
Upper Limb · 7 min read · Published 2025-11-15
Introduction
Lateral elbow pain is frequently diagnosed as "tennis elbow" (lateral epicondylitis). While this is the most common cause, two important differentials - radial tunnel syndrome and C6 cervical radiculopathy - can mimic or coexist with it. Failure to identify the correct diagnosis leads to failed treatment.
Lateral Epicondylitis (Tennis Elbow)
Pathology: Tendinopathy of the common extensor origin, primarily extensor carpi radialis brevis (ECRB), at the lateral epicondyle.
Pain location: Directly over or within 1–2cm of the lateral epicondyle.
Pain triggers: Gripping, wrist extension against resistance, lifting objects (especially with the palm down).
Examination:
- Point tenderness at the lateral epicondyle
- Pain with resisted wrist extension (Cozen's test)
- Pain with resisted middle finger extension (Maudsley's test - ECRB inserts near the 3rd metacarpal)
- Full, pain-free range of elbow motion
- Normal neurological exam
Radial Tunnel Syndrome
Pathology: Compression of the posterior interosseous nerve (PIN) within the radial tunnel - approximately 3–4 cm distal to the lateral epicondyle, as the nerve passes through the supinator muscle (arcade of Frohse).
Pain location: Distal and anterior to the lateral epicondyle. The maximum tenderness is over the radial tunnel, NOT the epicondyle itself.
Pain triggers: Similar to epicondylitis - resisted supination and wrist extension. However, the pain is deeper and more vague.
Examination:
- Tenderness 3–4cm distal to the lateral epicondyle (over the supinator muscle mass)
- Pain with resisted supination of the forearm
- Pain with resisted extension of the middle finger (Rule of Nines)
- No weakness initially (pain predominates; weakness appears in advanced cases/PIN syndrome)
- Night pain and aching are common
Key difference from epicondylitis: The point of maximum tenderness is DISTAL to the epicondyle, not at it.
C6 Cervical Radiculopathy
Pathology: Compression of the C6 nerve root, which innervates the wrist extensors and supplies sensation to the thumb and index finger.
Pain pattern: Neck pain radiating down the arm to the lateral elbow and forearm. May be confused with epicondylitis if the neck component is mild.
Examination:
- Neck pain or stiffness
- Spurling's test positive
- Weakness of biceps and/or wrist extensors (C6 myotome)
- Reduced biceps reflex
- Sensory changes in the thumb and index finger
- Elbow examination is normal (no tenderness at the epicondyle or radial tunnel)
Comparison
| Feature | Epicondylitis | Radial Tunnel | C6 Radiculopathy |
|---|---|---|---|
| Max tenderness | At epicondyle | 3–4cm distal | No local tenderness |
| Neck symptoms | No | No | Yes |
| Neurological signs | No | No (early) | Yes |
| Supination pain | Possible | Characteristic | No |
| Night symptoms | Mild | Common | Possible |
| Spurling's | Negative | Negative | Positive |
Clinical Pearl
Up to 5% of patients diagnosed with "tennis elbow" actually have radial tunnel syndrome. If a patient has failed standard epicondylitis treatment (rest, bracing, physiotherapy, injection) after 6–8 weeks, relocate the point of maximum tenderness - if it's distal to the epicondyle over the supinator, you've been treating the wrong diagnosis.
Summary
Tenderness at the epicondyle = lateral epicondylitis. Tenderness 3–4cm distal over the supinator = radial tunnel syndrome. Neck pain + arm radiation + reflex changes = C6 radiculopathy. Always palpate precisely - the location of tenderness is the diagnosis.
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