Effects of platelet-rich plasma combined with exercise therapy for one year on knee osteoarthritis: retrospective cohort study

Background Platelet-rich plasma (PRP) is a promising treatment for knee osteoarthritis (OA). However, exercise therapy and activities of daily living (ADL) guidance are recommended as core treatments in the Osteoarthritis Research Society International (OARSI) guidelines. However, the effects of PRP combined with exercise therapy are not fully understood. This study aimed to clarify the effectiveness of this treatment. Methods We assigned patients diagnosed with knee OA and treated between January 2021 and December 2022 to groups who underwent PRP + exercise (PE), PRP (P), or exercise (E) therapy. Outcomes were evaluated using Knee Injury and Osteoarthritis Outcome Scores (KOOS) before, and 1, 3, and 12 months after treatment. Within-group comparisons according to the time of each score were statistically assessed using a one-way analysis of variance, then differences were analyzed using Bonferroni multiple comparisons p < 0.05). Treatment responses were determined using Outcome Measures in Rheumatology (OMERACT)-OARSI Responder criteria. Results Pre-treatment KOOS did not significantly differ among the groups. Pain in the PE group improved within 1 month, symptoms, ADL, and quality of life (QOL) improved after 3, months and continued for 12 months. Pain and symptoms improved in the P group within 1 month, but ADLs and the QOL did not significantly change. Pain improved after 3 months in the E group and ADL, and QOL improved by 12 months. The response among the groups was the highest for the PE, with 50.0% at 1 and 3 months, and 65.0% at 12 months. Conclusions Therapy with PRP immediately relieved pain, whereas exercise conferred late, but enduring effects. Combining PRP with exercise conferred synergistic advantages that persisted for up to 12 months.