Objective: To determine the effectiveness of low-energy extracorporeal shock wave therapy (ESWT) in the treatment of previously untreated lateral epicondylitis.
Design: Randomized double-blind (patient and outcome assessor) controlled trial with power to show a clinically important difference in success rate between groups at the 0.05 level. Block randomization was stratified by unilateral or bilateral epicondylitis.
Setting: Community study at the University of Calgary.
Participants: Participants were recruited by poster advertisements in physicians' offices, fitness and sports centers, and postsecondary education institutions, and by e-mail to faculty and staff at those institutions. Inclusion criteria were tenderness over the lateral epicondyle and common extensor origin tendons that worsened with resisted wrist extension and hand grip and with elbow extension, forearm pronation, and wrist palmar flexion; presence of lateral epicondylitis for > or =3 weeks and <1 year; willingness to discontinue bracing; and age > or =18 years. Participants (mean age, 46 years; mean duration of symptoms, 21 weeks; 62% men) were informed that the purpose of the study was to compare 2 different treatment protocols.
Intervention: After telephone screening eligible persons were examined by 1 physician. All 60 participants were taught a single forearm extensor stretch (4 repetitions held for 20 seconds, 4 times per day). Persons in the active ESWT were assigned to 3 treatments, 1 per week for 3 weeks. In each session, 2000 pulses of 0.03 to 0.17 mJ/mm2, depending on the participant's pain tolerance, were administered. The sham treatment group was administered the lowest dose buffered by an air pad, on the same schedule.
Main outcome measures: The main outcome measure was treatment success or failure. Success was defined as > or =50% relief of pain overall from baseline, measured on a 10-cm visual analogue scale, with a maximum pain score of 4.0 cm, and no use of pain medication for lateral epicondylitis for 2 weeks before the 8-week evaluation. Bilaterally affected patients had to fulfill the success criteria for both arms. Change in quality of life and pain-free grip strength were also evaluated. Analysis was by intention to treat, including 4 patients (7%) lost to follow-up.
Main results: The proportions of treatment successes in the sham ESWT and the active ESWT were 31% and 39% (P = 0.533). Mean differences pretreatment to posttreatment in median overall pain scores for the more painful elbow were a reduction of 0.9 cm (SD, 0.4; 95% CI, 0.1-1.8) for the sham ESWT group compared with a reduction of 1.5 cm (SD, 0.5; CI, 0.5-2.4) for the active treatment group. Changes in pain-free grip strength and minimal changes for both groups in quality of life did not differ between groups.
Conclusions: Low-dose ESWT did not have a clinically important effect in reducing pain, improving quality of life, or increasing pain-free grip strength in middle-aged patients with previously untreated unilateral or bilateral lateral epicondylitis.