Treatment Effects of Subcutaneous Injections of Pentosan Polysulfate Sodium vs Placebo in Participants With Knee OA Pain

The purpose of this study is to measure the change in pain and function with subcutaneous injections of pentosan polysulfate sodium (PPS) compared with subcutaneous injections of placebo in participants with knee osteoarthritis pain. Study details include: * The study duration will be up to 31 weeks per participant * The treatment duration will be 6 weeks. * The visit frequency will be twice weekly during treatment. * The visit frequency will be every 4 weeks during the follow-up period.