What is the recommended approach for diagnosing tennis elbow (lateral epicondylitis) in a middle-aged patient with a history of repetitive wrist and forearm movements, presenting with lateral elbow pain and limited wrist and forearm range of motion?

How to Diagnose Tennis Elbow

Tennis elbow (lateral epicondylitis) is diagnosed primarily through clinical examination—specifically by eliciting tenderness directly over the lateral epicondyle combined with pain on resisted wrist extension—with plain radiographs of the elbow as the initial imaging study to exclude other pathology. 1, 2

Clinical Diagnosis

Key History Elements

• Repetitive wrist extension against resistance is the hallmark causative movement pattern, particularly in occupational activities involving repetitive forearm pronation/supination, computer use, or racquet sports 3, 2
• Patients typically report lateral elbow pain exacerbated by specific activities such as shaking hands, opening doors, or gripping with the wrist extended 3, 4
• The condition affects adults aged 40 and older and involves the dominant arm 75% of the time 3, 2
• Most cases arise from occupational stress rather than sports, despite the "tennis elbow" nomenclature 5

Physical Examination Findings

• Tenderness on direct palpation over the lateral epicondyle is the cardinal physical finding 2, 4
• Pain reproduced by resisted wrist extension with the elbow extended confirms the diagnosis 2, 4
• Weakened grip strength is commonly present 4
• Pain occurs during activities requiring wrist stabilization in extension while the elbow is straight 3

Critical Differential Diagnoses to Exclude

A thorough understanding of alternative diagnoses is imperative to prevent unnecessary testing 4:

• Radial nerve entrapment (posterior interosseous nerve syndrome) 1
• Inflammatory or arthritic conditions of the elbow joint 5
• Intra-articular pathology (osteochondral lesions, loose bodies) 1
• Occult stress fractures or other bone abnormalities 1

Imaging Approach

Initial Imaging

Plain radiographs of the elbow are usually appropriate as the initial imaging study for chronic elbow pain, including suspected tennis elbow 1. While radiographs are often normal in lateral epicondylosis, they may demonstrate:

• Soft tissue calcification at the common extensor origin 2
• Exclusion of other bony pathology 2

Advanced Imaging (When Indicated)

MRI or ultrasound should be reserved for specific clinical scenarios rather than routine diagnosis 2:

• Diagnosis remains unclear after clinical examination and radiographs 2
• Symptoms fail conservative treatment after 3-6 months 2
• Surgical intervention is being contemplated 2
• Need to demonstrate extent of tendon degeneration or exclude alternative diagnoses 2

According to the American College of Radiology, MRI elbow without IV contrast or CT elbow without IV contrast is usually appropriate as the next imaging study when radiographs are normal or nonspecific and occult pathology is suspected 1. However, for tennis elbow specifically, this advanced imaging is not routinely necessary for diagnosis.

Common Diagnostic Pitfalls

Avoid Over-Imaging

The diagnosis of tennis elbow is clinical, not radiographic 2, 4. Ordering MRI or ultrasound before attempting conservative management for 3-6 months represents unnecessary healthcare utilization, as approximately 80% of patients fully recover with conservative treatment alone 2.

Recognize Atypical Presentations

• While lateral epicondylitis is 7 to 10 times more common than medial epicondylitis, don't overlook medial pathology in patients with medial-sided symptoms 2
• Consider nerve entrapment syndromes when symptoms don't fit the classic pattern, as MRI can evaluate radial nerve, median nerve, and other entrapment syndromes 1

Understand the Pathophysiology

Tennis elbow represents a degenerative tendinopathy (epicondylosis) rather than an inflammatory process (epicondylitis), though the latter term persists in common usage 2, 4. This distinction matters for treatment selection, as the condition involves microtrauma at the common extensor origin rather than acute inflammation 3.