A PLACEBO-CONTROLLED DOUBLE-BLIND TRIAL TO EVALUATE THE EFFECTIVENESSOF PULSED SHORT-WAVE THERAPY FOR OSTEOARTHRITIC HIP AND KNEE PAIN

The aim of this study was to investigate the effectiveness of pulsed s hort wave (PSW) in the relief of pain in osteoarthritis of the hip and knee. Ninety-two patients, mean age 63 years, (34 men and 58 women) w ere randomly allocated to one of three groups: (1) Active PSW, using t he dosage found in a pilot study to be non-significantly most effectiv e, (2) Placebo PSW, (3) No treatment control group. Nine sessions of t reatment were provided over a 3-week period, each application lasting for 15 min. The machine was modified by the manufacturers so that the therapist was able to administer the treatment and carry out assessmen ts without being aware of the treatment allocation. Outcome measures i ncluded sensory and affective pain diary reports averaged over days an d weeks, self-reported benefit and the General Health Questionnaire. A nalysis of variance with repeated measures over time was used to find out if the active treatment had a specific effect, incremental to the placebo effect. There were no significant differences between the acti ve and placebo groups over time. According to the pain diary reports, both active and placebo groups tended to improve slightly during treat ment, but worsened after its withdrawal. Patients who were given the p lacebo application tended to report more benefit than those who had th e active treatment, although this did not quite reach statistical sign ificance (P < 0.06). Patients who were not on a waiting list for surge ry did significantly better over time than those who were (P < 0.03), There were no significant differences between the groups over time for the other outcome variables, Any treatment effect on this patient pop ulation appears to have been largely placebo-mediated. No evidence was found therefore for the specific effectiveness of PSW for treatment o f osteoarthritic hip or knee pain.