Platelet-rich plasma for knee osteoarthritis: a systematic review and meta-analysis of structural outcomes

To assess the impact of platelet-rich plasma (PRP) on imaging-based structural outcomes in patients with knee osteoarthritis (OA).

PubMed, Embase, and the Cochrane Library were systematically searched for randomized controlled trials (RCTs) published up to May 2026 evaluating imaging-based structural effects of PRP in knee OA. Risk ratio (RR) was used to evaluate binary outcomes and standardized mean differences (SMDs) or mean differences (MDs) for continuous endpoints, with 95% confidence intervals (CIs).

A total of 12 RCTs involving 1,200 patients were included. PRP was associated with greater improvement in patellofemoral cartilage thickness/volume compared with control treatments (SMD 0.94; 95% CI, 0.53 to 1.34), whereas no significant differences were observed for medial tibial cartilage thickness/volume or cartilage defect progression. Magnetic resonance imaging (MRI)-based structural scores showed no between-group differences in Whole-Organ Magnetic Resonance Imaging Score (WORMS) osteophytes or subchondral cysts, although PRP demonstrated a significant reduction in bone marrow edema (SMD - 0.40; 95% CI, - 0.71 to - 0.09). Synovitis did not differ overall between groups (SMD - 0.22; 95% CI, - 0.43 to 0.00).

In this systematic review and meta-analysis, PRP demonstrated limited and inconsistent effects on imaging-based structural outcomes in knee OA, and did not confer significant and consistent benefits in medial tibial cartilage measurements, cartilage defect progression, synovitis, or most WORMS domains. The favorable findings observed for patellofemoral cartilage and bone marrow edema should be interpreted with caution. Thus, the findings do not provide clear evidence supporting PRP as a structural disease-modifying treatment, and additional high-quality RCTs using standardized imaging endpoints are warranted.