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.