Study design: Randomized clinical trial. Objective: To evaluate the effect of PSW treatment in different doses and to compare to the control and placebo group.

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 short wave has been widely used, but the optimal dose and application time still have not been well established.

Methods: One hundred and twenty-one females (average ± sd age, 60 ± 9 years), with a diagnosis of knee OA were distributed randomly into 4 groups: 35 patients who did not receive any treatment (control), 23 patients in the placebo group, 32 patients in the low dose PSW group (14.5W, 19 minutes and 17KJ), and 31 patients in the high dose PSW group (14.5W, 38 minutes and 33KJ). An 11-point numerical pain rating scale (NPRS) and "Knee Osteoarthritis Outcome Score" (KOOS) were used to assess pain and function in 3 stages: initial evaluation (pre-treatment), immediately after post-treatment, and a 12-month follow up.

Results: The 4 groups were homogeneous prior to treatment with respect to demographics, pain, and functional scales data. We demonstrated the short-term effectiveness of the PSW at low or high doses in patients with knee OA. Both treatment groups showed significant improvement in pain and function when compared to the control and placebo groups (P<0.05). There were no differences between PSW doses, despite the fact that a low dose of PSW seems to be more effective in the long term.

Conclusion: The PSW is an effective method for pain relief, functionality, and quality of life improvement in females with knee osteoarthritis in the short-term. On the basis of our results, we recommend PSW application 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.

Inclusion Criteria:

• The female subjects were included if they were over 40 with knee primary grade II or III OA, based on Gupta et al radiographic criteria2, and joint or anterior knee pain for at least 3 months.

Exclusion Criteria:

• We excluded patients with a history of surgery or any invasive procedure of the affected knee, physical therapy for knee injuries or any medication that had changed in the last 3 months, other diseases changing function, and patients who presented any contraindication for PSW application, especially metallic implants, pacemakers, lack of sensitivity, or tumor.