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.