This is a follow-up extension study to determine duration of treatment effect and assess long-term safety and response to re-treatment with PPS in participants with knee OA pain who completed the parent study study (PARA_OA_002).~Study PARA_OA_006 consists of Follow-up Part 1 and Part 2 and a Treatment Part~Eligible participants will be enrolled in Study PARA_OA_006 at the completion of the parent study and will enter the 6-month Follow-up Part 1. At the end of Follow-up Part 1, participants will begin the Treatment Part of the study, continue to Follow-up Part 2, or end the study depending on the treatment received in the parent study, their response to treatment during the parent study, and/or their response status at the end of the Follow-up Part 1~Participants in the Treatment Part will be administered twice weekly subcutaneous (SC) injections for 6 weeks:~The PPS dose regimen will be 1 of the 3 dose regimens evaluated in Stage 1 of the parent study and selected by the independent data monitoring committee (DMC).~Placebo will be 0.9% w/v sodium chloride injection.~The maximum duration of study participation will be approximately:~28 weeks for participants who complete Follow-up Part 1 and are not eligible to continue to Follow-up Part 2 or the Treatment Part~56 weeks for participants who complete Follow-up Part 1 and the Treatment Part~68 weeks for participants who complete Follow-up Part 1, Follow-up Part 2 up to Week 40, and the Treatment Part~80 weeks for participants who complete Follow-up Parts 1 and 2 or Follow-up Part 1, Follow-up Part 2 up to Week 52 and the Treatment Part
The purpose of this study is to measure the duration of treatment effect and response to re-treatment with subcutaneous injections of pentosan polysulfate sodium (PPS) compared with placebo in adult participants with knee osteoarthritis (OA) pain.~Study details include:~The study duration will be up to 28, 56, 68, or 80 weeks depending on treatment received in the parent study and response to treatment.~If participating in the Treatment Part of the study:~The treatment duration will be up to 6 weeks~The visit frequency will be twice weekly during the Treatment Period.