Impact of platelet-rich plasma (PRP) intra-articular injection on functioning and kinematic analysis in knee osteoarthritis patients: A prospective observational study

Purpose Osteoarthritis (OA) is a degenerative joint disease primarily affecting elderly, with the knee being the most involved joint. Platelet-Rich Plasma (PRP) therapy has shown promise in OA management. Our study aimed to descriptively characterize changes over time in performance, pain, stiffness, and function among patients with knee OA undergoing a combined PRP and physiotherapy protocol. Methods This study included patients over 50 years of age with a Kellgren-Lawrence II-III grade of OA. The intervention involved three PRP injections and rehabilitation cycles. Outcomes assessed functional capacity with six minutes walking test (6MWT) and the time-up-and-go (TUG), via an inertial motion unit. OA clinical severity was assessed through Western Ontario and McMaster University Osteoarthritis Index (WOMAC), Numerical Rating Scale (NRS), and EuroQol Visual Analogue Scale (EQ-VAS). Results We included 64 patients (males/females = 23/41), of whom 42 had complete data across T0–T4. WOMAC and NRS scores decreased during the early follow-up period, reaching their lowest values at T2, followed by progressive increases at T3 and T4. TUG showed a significant overall change over time, although no consecutive comparison remained significant after correction for multiple comparisons. No significant changes over time were observed in 6MWT or gait-related outcomes. Conclusions Under the combined PRP and physiotherapy protocol, early changes in pain and function were observed, followed by a partial reversal at later follow-ups. No statistically significant changes over time were observed in 6MWT or gait-related outcomes. Given the uncontrolled single-arm design, these findings are descriptive and cannot establish the effectiveness or specific contribution of PRP. Further controlled studies are required.