What Is Tennis Elbow and Why Won't It Go Away?

Anatomy of the Lateral Elbow

The lateral epicondyle of the humerus is the bony prominence on the outer aspect of the elbow that serves as the common origin for the wrist and finger extensor muscles. The extensor carpi radialis brevis (ECRB) is the most clinically significant of these muscles — its tendon originates from the anterior face of the lateral epicondyle and is subject to the highest compressive and tensile forces during wrist extension and gripping activities, making it the primary site of pathology in lateral epicondylalgia. The extensor digitorum communis, extensor carpi radialis longus, and extensor carpi ulnaris also originate in this region and may contribute to symptom generation in more widespread presentations.

What Is Lateral Epicondylalgia?

The contemporary preferred term for "tennis elbow" is lateral epicondylalgia — a name that reflects its clinical character (pain at the lateral epicondyle) without the misleading implication of acute inflammation that "epicondylitis" carries. As with plantar fasciitis, histological analysis of biopsied tissue from lateral epicondylalgia presentations consistently demonstrates angiofibroblastic degeneration — disordered collagen, hypercellularity, and neovascularisation — without the inflammatory cell infiltration that defines true inflammatory tendinopathy. It is a degenerative condition of the ECRB enthesis driven by cumulative load exceeding the tissue's adaptive capacity.

Despite its name, only approximately 5% of cases occur in tennis players. The majority of presentations involve workers performing repetitive gripping, wrist extension, and forearm rotation tasks — plumbers, carpenters, office workers with sustained mouse use, chefs, and manual labourers are disproportionately represented.

Why Does It Persist?

Lateral epicondylalgia is notorious for its clinical stubbornness — population-based studies report that up to 20% of cases remain symptomatic at one year without appropriate treatment, and many patients experience intermittent recurrence over months to years. Several factors contribute to this persistence. First, the ECRB is loaded with virtually every gripping and wrist-loading activity of daily life, making true relative rest difficult to achieve. Second, the avascular zone of the ECRB enthesis has a limited intrinsic healing capacity relative to the continuous mechanical demand placed on it. Third, many patients receive treatments (cortisone injections, repeated stretching, anti-inflammatory medications) that provide short-term symptom relief without addressing the underlying degenerative tendon pathology — creating a cycle of apparent recovery followed by recurrence. Fourth, central sensitisation develops in a proportion of chronic presentations, meaning that the pain system has become sensitised beyond what peripheral tendon pathology alone would generate.

Clinical Diagnosis

Diagnosis is clinical. The diagnostic triad is: localised tenderness over the lateral epicondyle (specifically at the ECRB origin, 1–2cm distal to the epicondyle apex); pain reproduced by resisted wrist extension with the elbow extended; and pain reproduced by resisted middle finger extension (the Maudsley test). Grip strength is typically reduced on the affected side, and grip testing in elbow extension reproduces or worsens pain. Differential diagnoses to consider include radial tunnel syndrome (which presents with pain 3–4cm distal to the lateral epicondyle over the radial tunnel, without the resisted extension provocation), posterior interosseous nerve entrapment, and referred pain from the cervical spine (which should be assessed in all lateral elbow presentations).

Evidence-Based Management

The most evidence-supported management programme combines load management, progressive tendon loading, manual therapy, and education. Load management identifies and modifies the specific activities driving the load-capacity mismatch — grip load, wrist extension volume, forearm rotation — while maintaining conditioning. Progressive loading using isometric wrist extension (immediate analgesic effect and stimulus for adaptation) progressing to isotonic and then functional loading is the primary rehabilitation intervention. Manual therapy — soft tissue release to the extensor muscle belly, cervical and thoracic mobilisation, and wrist manipulation — provides adjunctive pain relief and addresses contributing neural and joint factors. Dry needling to the ECRB and common extensor origin reduces myofascial hypertonicity and has evidence for direct tendinopathy management. Lateral elbow bracing (counterforce strap) reduces peak force at the ECRB origin during gripping and provides useful symptomatic support during activity.

What Doesn't Work

Several widely used interventions for lateral epicondylalgia have poor long-term evidence. Corticosteroid injection produces the best short-term outcomes of any intervention but the worst outcomes at 12 months — its use should be reserved for cases where short-term pain relief is required to enable rehabilitation engagement, not as a standalone treatment. Prolonged rest without progressive reloading allows symptom settlement but does not drive tendon adaptation, and symptoms reliably return on resumption of loading. Repetitive stretching of the extensor tendon in isolation, without progressive loading, does not stimulate structural repair. Platelet-rich plasma (PRP) injection has generated significant commercial interest but randomised controlled trial evidence does not consistently demonstrate superiority over saline injection or exercise alone.