Joost Peerbooms

68 Chapter 5 score (VAS) for pain (0, no pain; 100 maximum pain possible). Lateral epicondylitis was defined as pain over the lateral epicondyle on direct palpation and pain in that area during resisted wrist extension. All affected elbows were screened with radiography and all proved to be normal, except for some calcifications of the common extensor origin. Sonography and magnetic resonance imaging were not standardly used. Patients had a clinical diagnosis of lateral epicondylitis, or lateral elbow pain increased by pressure on the lateral epicondyle and during resisted extension of the wrist. All patients suffered for more than 6 months. Before 6 months of the trial, they were treated with cast immobilization, injections with corticosteroids, or physiotherapy. Exclusion criteria were as follows: age less than 18 years, pregnancy, history of carpal tunnel syndrome or cervical radiculopathy, and systemic disorders such as diabetes, rheumatoid arthritis, and hepatitis. Also, patients were excluded if they had been treated for lateral epicondylitis with surgical intervention or with a corticosteroid injection in the past 6 months. The primary endpoint was a 25% reduction in the VAS score or DASH Outcome Measure score (DASH: Disabilities of the Arm, Shoulder, and Hand) without a reintervention after 1 year. In the current study, we tested the hypothesis that the injection of concentrated autologous platelets increases the healing of patients with tendinitis compared with those treated with a steroid injection. Statistical data were collected to determine the power of both groups. Successful treatment in the PRP group was determined by using the results of Mishra and Pavelko. 10 In this study, 93% of the patients with chronic lateral epicondylitis that received PRP were considered successful-that is, with more than a 25% decrease in pain. Successful treatment in the control group was determined by using the results of Hay and colleagues, 6 who studied the effect of corticosteroid injections for chronic lateral epicondylitis. Full recovery or decrease in complaints without complications was seen in 65% of the patients in the corticosteroid group. With a bilateral alpha of .05 and a power of 90% (p1 = .93 and p2 = .65), 42 patients per group are necessary to measure the difference with the Chi-square test. To correct for the patients who were lost to follow-up, we included a minimum of 50 patients in each group. The Medical Ethical Committee and the National and Institutional Review Board approved the study. Randomization Randomization was performed after patients were deemed eligible and had provided informed consent. Patients were randomly allocated to the concentrated autologous platelet group (PRP group) or the corticosteroid group (control group). A computer using block randomization of 10 patients was used to create a randomization schedule. Treatment assignments (placed in sequentially numbered opaque envelopes) were assigned by the trial managers, who also arranged the facilities needed for the procedure.