Differential Diagnoses for Medial and Lateral Epicondylitis
When evaluating elbow pain localized to the epicondyles, you must systematically exclude other pathologies that can mimic epicondylitis, as the differential diagnosis is broad and includes osseous, soft tissue, cartilaginous, and nerve-related abnormalities 1.
Lateral Epicondylitis (Tennis Elbow) Differentials
Primary Considerations:
- Radial tunnel syndrome - Compression of the posterior interosseous nerve; distinguished by pain 4-5 cm distal to lateral epicondyle, worsened by resisted supination with elbow extended
- Posterior interosseous nerve entrapment - Pain radiates down forearm, weakness in finger/thumb extension without sensory loss
- Radiocapitellar arthritis - Pain with forearm rotation, crepitus, limited range of motion
- Osteochondral lesions of capitellum - More common in throwing athletes and adolescents; mechanical symptoms may be present
- Lateral collateral ligament injury - Posterolateral rotatory instability, history of trauma or repetitive valgus stress 2
- Cervical radiculopathy (C6-C7) - Neck pain, dermatomal sensory changes, proximal radiation of symptoms 3
Additional Pathologies to Exclude:
- Intra-articular loose bodies
- Heterotopic ossification
- Occult fractures (radial head, capitellum)
- Synovial abnormalities (plica, synovitis)
- Referred pain from shoulder pathology 1
Medial Epicondylitis (Golfer's Elbow) Differentials
Primary Considerations:
- Ulnar collateral ligament (UCL) injury - Critical in overhead throwers; valgus instability, positive milking maneuver, pain with valgus stress 2, 3
- Cubital tunnel syndrome - Ulnar nerve compression; paresthesias in ring/small fingers, positive Tinel's sign at cubital tunnel, intrinsic hand weakness 1, 3
- Ulnar neuritis - Similar to cubital tunnel but may be dynamic; symptoms with elbow flexion
- Medial collateral ligament sprain - History of acute valgus stress or chronic overload
- Cervical radiculopathy (C7-C8) - Neck symptoms, dermatomal distribution, proximal radiation 3
Additional Pathologies to Exclude:
- Distal triceps pathology (altered anatomy, tendinopathy)
- Medial epicondyle avulsion fracture (especially post-trauma)
- "Little League elbow" in children - Medial epicondyle apophysitis or avulsion; critical to identify in skeletally immature patients 3
- Elbow osteoarthritis with medial joint involvement
- Flexor-pronator muscle strain (acute vs. chronic)
- Valgus extension overload syndrome (posterior medial impingement)
- Referred pain from shoulder or wrist 3
Clinical Approach to Differentiation
Key Examination Findings:
For lateral epicondylitis, look for:
- Maximal tenderness 1 cm distal and anterior to lateral epicondyle
- Pain with resisted wrist extension (Cozen's test) and middle finger extension
- Pain with resisted supination
- Normal neurological examination
For medial epicondylitis, look for:
- Tenderness at or just distal to medial epicondyle
- Pain with resisted wrist flexion and forearm pronation (reverse Cozen's test)
- Mandatory ulnar nerve examination - Tinel's sign, intrinsic muscle strength, two-point discrimination 3
- Valgus stress testing if UCL injury suspected
Red Flags Requiring Further Investigation:
- Mechanical symptoms (locking, catching) → suspect intra-articular pathology
- Neurological deficits → nerve compression or radiculopathy
- History of significant trauma → fracture or ligament rupture
- Night pain or rest pain → consider infection, tumor, or severe inflammatory process
- Bilateral involvement → systemic inflammatory condition
- Failure to respond to 6 months of appropriate conservative treatment → consider alternative diagnosis 4
Imaging Strategy
Initial radiographs are mandatory to exclude osseous pathology (fractures, arthritis, loose bodies, heterotopic ossification, soft tissue calcification) 1.
For suspected soft tissue or ligamentous injury with normal radiographs, ultrasound or MRI without contrast are equivalent next steps 2. Ultrasound offers dynamic assessment and is particularly useful for UCL evaluation with stress maneuvers (96% sensitivity for UCL tears) 2.
Electromyography is indicated when nerve symptoms are present to differentiate radiculopathy from peripheral nerve entrapment 1.
Common Pitfalls
- Assuming all lateral elbow pain is tennis elbow - Radial tunnel syndrome is frequently misdiagnosed as lateral epicondylitis; key distinction is location of maximal tenderness
- Missing concomitant ulnar nerve pathology with medial epicondylitis - Always examine the ulnar nerve; cubital tunnel syndrome coexists in a significant proportion of cases 3
- Overlooking UCL injury in overhead athletes - Medial elbow pain in throwers is UCL injury until proven otherwise
- Failing to examine the cervical spine - Radiculopathy can refer pain to either epicondyle
- Not recognizing bilateral epicondylar involvement - Though rare, simultaneous lateral and medial epicondylitis can occur in the same elbow 5
- Repeated corticosteroid injections without reassessment - If symptoms persist after 2-3 injections, reconsider the diagnosis 5