Lateral Epicondylitis: Tennis Elbow

What Is Lateral Epicondylitis?

Lateral epicondylitis, popularly known as "tennis elbow," is a painful condition that affects the wrist and finger extensor tendons at their insertion on the lateral epicondyle of the humerus — the bony prominence on the outer side of the elbow.

Despite the popular name, most patients with lateral epicondylitis do not play tennis. The condition is far more common in manual workers and professionals who perform repetitive wrist extension and gripping movements.

As with plantar fasciitis, the term "epicondylitis" (which suggests inflammation) is imprecise for the chronic phase. Histopathological studies show that the predominant process is degenerative tendinopathy (tendinosis), with disorganization of collagen fibers and neovascularization.

Epidemiology

Lateral epicondylitis affects 1-3% of the general population, with a peak incidence between ages 35 and 54. It is equally common in men and women in the general population, although among manual workers men are more affected. The dominant arm is involved in 75% of cases.

High-risk professions include plumbers, painters, carpenters, butchers, cooks, mechanics, and assembly-line workers. In sports, in addition to tennis, sports such as squash, badminton, and golf (top hand) are also risk factors.

Pathophysiology

The most frequently affected tendon is that of the extensor carpi radialis brevis (ECRB), which originates at the lateral epicondyle of the humerus. This tendon is vulnerable due to its anatomical position: during forearm extension and pronation, it is compressed against the radial head.

Pathological Process

Repetitive overload causes microtears at the origin of the ECRB. In the acute phase, an inflammatory response occurs with release of prostaglandins and cytokines. If the overload persists without adequate recovery time, the process evolves to tendinosis.

In tendinosis, disorganized collagen fibers, increased ground substance, neovascularization with neoinnervation (new blood vessels accompanied by new sensory nerves), and absence of inflammatory cells are observed. This neovascularization may be a source of pain, since the new nerves accompanying the vessels transmit nociceptive signals.

The angiofibroblastic degeneration described by Nirschl — with fragmented collagen fibers, immature fibroblasts, and vascular granulation tissue — is the classic histopathological finding of chronic lateral epicondylitis.

Symptoms

Symptoms generally develop gradually, without a clear traumatic event. Pain is the main symptom, located on the lateral aspect of the elbow.

Diagnosis

Diagnosis is clinical in the vast majority of cases. Specific provocative tests reproduce the pain and confirm the diagnosis with high accuracy.

Radial Tunnel Syndrome

Radial tunnel syndrome results from compression of the posterior interosseous nerve (deep branch of the radial nerve) in the radial tunnel, a passage between the muscular planes of the proximal forearm. It is frequently confused with lateral epicondylitis, since both cause pain in the lateral elbow region. The fundamental difference is anatomical and clinical: in radial tunnel syndrome, pain is located 3-5 cm more distal to the epicondyle (over the radial head), and palpation over the arcade of Frohse reproduces pain with specificity.

The most useful diagnostic test is resisted middle-finger extension (Maudsley's test), which compresses the posterior interosseous nerve and produces pain distal to the epicondyle — different from epicondylitis, where pain is at the epicondyle itself. Electromyography may be normal or show subtle conduction delay. Treatment includes surgical decompression in refractory cases, after failure of conservative treatment for 3-6 months.

Medial Epicondylitis

Medial epicondylitis ("golfer's elbow") is the medial counterpart of lateral epicondylitis, affecting the origin of the wrist flexor and pronator muscles at the medial epicondyle. The anatomical distinction is direct: pain is on the inner aspect of the elbow, not the outer. However, some patients present with simultaneous involvement of both epicondyles, especially manual workers with high repetitive demand.

Provocative tests distinguish the two conditions accurately: in medial epicondylitis, pain is reproduced by resisted wrist flexion with the elbow extended (golfer's elbow test) and by resisted pronation; in lateral epicondylitis, by resisted extension and supination. Medial epicondylitis has a stronger association with ulnar nerve neuropathy (present in 40-60% of cases), requiring specific evaluation of ulnar function.

Elbow Arthropathy

Elbow osteoarthritis can cause lateral pain that simulates epicondylitis, especially when it involves the radiocapitellar joint. The picture is distinguished by the presence of joint range-of-motion limitation (full extension frequently impossible), audible and palpable crepitus during movements, and, in advanced forms, visible joint deformity. Pain is diffuse and related to any elbow movement, not just resisted wrist extension.

Plain X-ray of the elbow in anteroposterior and lateral views reveals joint-space narrowing, osteophytes, and intra-articular loose bodies. Computed tomography assesses bone changes in greater detail, while MRI is useful for evaluating associated cartilage and ligament lesions. Conservative treatment includes analgesia, physical therapy, and, in advanced cases, arthroplasty or resection arthroplasty.

C6/C7 Radiculopathy

Cervical radiculopathy at the C6 and C7 levels can refer pain along the forearm and lateral elbow, mimicking lateral epicondylitis. Clinical distinction is based on the presence of cervical symptoms (neck pain or stiffness, pain radiating from the neck to the arm), paresthesias in a specific dermatome (C6: thumb and index finger; C7: middle finger), and altered reflexes (C6: brachioradialis reflex; C7: triceps reflex).

The Spurling test — foraminal compression with ipsilateral cervical inclination — reproduces radicular pain and guides diagnosis. In doubtful cases, electromyography differentiates peripheral injury (epicondylitis with possible local neuropathy) from cervical radicular injury. It is essential to rule out radiculopathy before indicating local invasive treatments (injections) for epicondylitis, in order not to mask a condition requiring specific treatment.

Olecranon Bursitis

Olecranon bursitis — inflammation of the bursa between the olecranon and the skin — is easily distinguished from lateral epicondylitis by its posterior location and by the presence of visible, fluctuant swelling at the tip of the elbow. When large, it can cause pain that radiates laterally, creating some diagnostic confusion. Palpation shows fluid fluctuation directly over the olecranon, without pain on passive elbow movement within normal ranges.

Bursitis can be aseptic (traumatic or from repetitive microstress on supports) or septic (infectious), and it is essential to distinguish the two. A tense, erythematous, hot bursa with fever points to infection and requires diagnostic puncture with fluid analysis. Aseptic bursitis responds well to compression, mechanical protection, and, occasionally, aspiration. Antibiotic therapy is reserved for proven infectious cases.

Treatments

Conservative treatment is effective in most cases, with a resolution rate of 80-95% at 12 months. The keys to treatment are load modification and progressive exercise.

Eccentric Exercise

Eccentric exercise of the wrist extensors is the treatment with the highest level of evidence. With the forearm pronated on a table, the patient holds a light weight (0.5-1 kg) and slowly lowers the wrist into flexion (eccentric phase), returning to the starting position with the help of the other hand. Perform 3 sets of 15 repetitions, twice a day.

The mechanism of eccentric exercise involves stimulation of type I collagen synthesis, realignment of tendon fibers, reduction of pathological neovascularization, and gradual strengthening of the musculotendinous unit.

Load progression should be gradual: increase the weight only when the exercise can be performed without significant pain (up to 3/10 on the pain scale is acceptable).

Acupuncture as Treatment

Acupuncture has been studied as adjuvant therapy in lateral epicondylitis. A Cochrane review (Green et al., 2002, subsequently updated) reported that acupuncture may provide short-term pain relief (2-8 weeks) compared with controls, with evidence quality limited by the number and size of available trials.

Mechanisms include inhibition of local nociceptive transmission, reduction of pro-inflammatory cytokines in peritendinous tissue, improved local blood flow, and release of growth factors that may favor tendon healing.

Acupuncture may be especially useful in the early phases of treatment, when pain prevents adequate performance of eccentric exercises. By reducing pain, it allows faster progression of the rehabilitation program.

Prognosis

Lateral epicondylitis is a self-limited condition in most cases. About 80-90% of patients improve with conservative treatment within 12 months. The recurrence rate is approximately 8-15%, especially when occupational factors are not modified.

Myths and Facts

When to Seek Medical Help