The investigators hypothesized that lidocain injection is as effective as corticosteroid injection in management of tennis elbow, and if so, it may replace corticosteroid injection in the management of tennis elbow.

Lateral epicondylitis or tennis elbow is a tendinopathy of the common extensor origin of the lateral elbow, and is estimated to have an annual incidence of 1-3%. It is characterized by tenderness over the lateral epicondyle of the humerus, normal range of motion, and pain on resisted extension of the wrist or fingers. Symptoms can persist for between 6 months and 2 years but usually resolve within 12 months. Although tennis elbow is often self-limited, around 20% of cases are refractory to conservative care. Tennis elbow is now thought to be non-inflammatory, and the pathologies are characterized by collagen degeneration, fibroblast proliferation, mucoid degeneration, and neovascularization.

Treatment of tennis elbow includes relative rest, physical therapy (therapeutic exercise, massage, therapeutic ultrasound, lower power laser, etc.), analgesics, non-steroidal anti-inflammatory drugs, glyceryl trinitrate patches, injection therapy (corticosteroid, hyaluronan gel, botulinum toxin, and autologous platelet-rich plasma), shock wave therapy, and even surgery. Previous studies showed corticosteroid injection is effective in the short term, but is harmful in the long-term, and is more likely to have a recurrence. In consideration of a degenerative lesion in tennis elbow, corticosteroid injection may be not an ideal agent. Although plate-rich plasma injection showed promising results, the high cost limited its widespread clinical use. Since local lidocain injection is commonly used in the management of myofascial pain syndrome, it might be effective in the treatment of tendinopathy like tennis elbow. The purpose of this study is to compare the effect of corticosteroid injection and lidocain injection in the treatment of tennis elbow. The investigators hypothesized that lidocain injection is as effective as corticosteroid injection in management of tennis elbow, and if so, it may replace corticosteroid injection in the management of tennis elbow.

Inclusion Criteria:

• Between 20 and 75 years of age, with lateral elbow pain ≥4 in pain VAS for at least 1 month
• Reproducibility of pain by 2 or more of the following tests: palpation of the lateral epicondyle and/or the common extensor origin of the elbow; resisted wrist extension (dorsiflexion) and pronation with the elbow in extension
• Pain reproduced by static stretching of the pronated wrist in palmar flexion with the elbow in extension.

Exclusion Criteria:

• not fulfill inclusion criteria