Background: Several forms of conservative treatment have been the focus of many recent studies in knee osteoarthritis (OA). Among these techniques, the application of pulsed shortwave (PSW) treatment has been widely used, but the optimal dose and application time have not been well established. Objective The purposes of this study were: (1) evaluate the effect of PSW treatment in different doses and (2) to compare low-dose and high-dose PSW groups with control and placebo groups. Design This was a randomized clinical trial. Setting The study was conducted in the physical therapy department of 2 large urban hospitals. Patients One hundred twenty-one women (mean age=60 years, SD=9) with a diagnosis of knee OA participated in the study.
Intervention and measurements: Participants were distributed randomly into 4 groups: 35 participants did not receive any treatment (control group), 23 received a placebo treatment, 32 received low-dose PSW treatment (power of 14.5 W, treatment duration of 19 minutes, and total energy of 17 kJ), and 31 received high-dose PSW treatment (power of 14.5 W, treatment duration of 38 minutes, and total energy of 33 kJ). An 11-point numerical pain rating scale and the Knee Osteoarthritis Outcome Score were used to assess pain and function in 3 stages: at initial evaluation (pretreatment), immediately after treatment, and at 12-month follow-up.
Results: The 4 groups were homogeneous prior to treatment with respect to demographics, pain, and functional scale data. The results demonstrated the short-term effectiveness of the PSW at low and high doses in patients with knee OA. Both treatment groups showed a significant reduction in pain and improvement in function compared with the control and placebo groups (effect size: range=20.0-23.4 for the low-dose PSW group and range=15.7-16.5 for the high-dose PSW group). There were no differences in results between PSW doses, although a low dose of PSW appeared to be more effective in the long term. Limitations These results were achieved without physical exercise, which could have positively influenced the results.
Conclusions: Pulsed shortwave treatment is an effective method for pain relief and improvement of function and quality of life in the short term in women with knee OA. On the basis of the results, application of PSW treatment is recommended in the female population with knee OA. However, conclusions regarding the 12-month follow-up should be analyzed carefully due to the high dropout rate.
Trial registration: ClinicalTrials.gov NCT01331174.