What is the likely diagnosis for a patient experiencing pain on the posterior lateral aspect of the elbow joint radiating to the thumb?

Diagnosis: Lateral Epicondylitis (Tennis Elbow)

The clinical presentation of pain on the posterior lateral aspect of the elbow radiating to the thumb is most consistent with lateral epicondylitis, a degenerative tendinopathy of the common extensor origin, particularly affecting the extensor carpi radialis brevis tendon. 1

Clinical Presentation and Pathophysiology

• Lateral epicondylitis results from repetitive wrist extension, radial deviation, and forearm supination causing degenerative changes at the common extensor origin. 1
• The condition affects men and women equally, most commonly after age 40, and involves the dominant arm in 75% of cases. 2, 1
• Pain radiating toward the thumb follows the anatomic distribution of the extensor carpi radialis brevis and longus tendons. 1

Diagnostic Workup

Begin with plain radiographs of the elbow as the most appropriate initial imaging study to rule out other causes of elbow pain. 2, 1

Initial Imaging

• Standard elbow radiographs can identify intra-articular bodies, heterotopic ossification, osteochondral lesions, soft tissue calcification, occult fractures, and osteoarthritis. 1
• Comparison views of the contralateral elbow are often useful. 1

Advanced Imaging (If Radiographs Normal)

• MRI without IV contrast or ultrasound are equivalent alternatives for suspected tendon degeneration or tear when radiographs are normal or indeterminate. 2, 1
• MRI demonstrates 76% sensitivity and 50% specificity for tendon pathology. 2
• Ultrasound shows 64.52% sensitivity and 85.19% specificity for common extensor tendon tears. 2

Red Flags Requiring Further Evaluation

• Night pain or pain at rest suggests inflammatory or neoplastic process. 1
• Mechanical symptoms (locking, catching) suggest intra-articular pathology. 1
• Neurologic symptoms warrant EMG and nerve conduction studies to evaluate for posterior interosseous nerve syndrome or radial tunnel syndrome. 1

Treatment Algorithm

First-Line Conservative Management (80% recover within 3-6 months)

Begin with relative rest, activity modification, and eccentric strengthening exercises as the foundation of treatment. 1

Core Interventions

• Relative rest and activity modification to reduce repetitive loading of the damaged tendon. 1, 3
• Eccentric strengthening exercises to promote tendon healing and increase strength. 1, 3
• Cryotherapy (ice application) for 10-minute periods for acute pain relief. 1, 3
• Progressive stretching exercises for wrist extensors. 1

Adjunctive Therapies

• NSAIDs provide short-term pain relief but do not affect long-term outcomes. 2, 1, 3
• Counterforce bracing (tennis elbow brace) may improve function during daily activities, though evidence is limited. 1, 3
• Deep transverse friction massage to reduce pain. 1, 3
• Manual joint mobilization combined with exercise therapy is more effective than exercise alone. 1

Second-Line Treatment

Corticosteroid injections are more effective than NSAIDs in the acute phase but do not change long-term outcomes—use judiciously for short-term relief only. 2, 1, 3

Common Pitfalls

• Avoid relying solely on corticosteroid injections, as they provide only temporary relief without addressing underlying tendon degeneration. 2, 1
• Do not skip activity modification and eccentric exercises, which are the most evidence-based interventions for long-term recovery. 1
• Extracorporeal shock wave therapy has demonstrated mixed benefit and should not be considered first-line. 2

Surgical Referral

If pain persists despite 3-6 months of well-managed conservative treatment, refer to orthopedic surgery for evaluation. 2

• Surgical techniques include excision of abnormal tendon tissue and longitudinal tenotomies to release areas of scarring and fibrosis. 2
• Both open and arthroscopic methods are acceptable with excellent results. 4
• Surgery should only be used as a last resort in severe, recalcitrant cases. 5, 6