Platelet-rich plasma versus hyaluronic acid injections for knee osteoarthritis: a propensity-score analysis

Background and Aims: Intra-articular injections of viscosupplements have been an option in the treatment of knee osteoarthritis. Platelet-rich plasma is an experimental treatment in osteoarthritis. Previous studies have shown that platelet-rich plasma reduces osteoarthritis symptoms in similar proportions as viscosupplements. The aim of this study was to compare platelet-rich plasma versus viscosupplements in terms of symptoms' relief and time to arthroplasty. Material and Methods: A total of 190 patients included in this retrospective study received either intra-articular injections of platelet-rich plasma (94 patients) or hyaluronic acid (86 patients) between January 2014 and October 2017. Western Ontario and McMaster Universities Osteoarthritis Index, Visual Analogue Scale, and range of motion were measured before injection, at 15 days, 6 months, 12 months, and at last follow-up. We compared outcomes between these two groups using propensity score analysis for risk adjustment in multivariate analysis and for one-to-one matching. Results: Hyaluronic acid-treated patients experienced a higher arthroplasty rate (36.0% vs 5.3%, p < 0.001), lower range of motion, worse Visual Analogue Scale and Western Ontario and McMaster Universities Osteoarthritis Index scores, and increased risk of any arthroplasty occurrence (log-rank < 0.001) than platelet-rich plasma patients. Cox proportional hazards analysis revealed a tendency to decrease the risk of knee arthroplasty for the patients treated by platelet-rich plasma (hazard ratio = 0.23, 95% confidence interval, 0.05-1.05, p = 0.058). When the treatment method was adjusted for propensity score in the propensity score-matched pairs (n = 78), we found that platelet-rich plasma group still showed significant improvement over the hyaluronic acid group in arthroplasty rate (12.8% vs 41.0%, p = 0.010), Visual Analogue Scale and Western Ontario and McMaster Universities Osteoarthritis Index scores, but not in the range of motion, during the mean follow-up of 16.7 months. Conclusion: Intra-articular injections of platelet-rich plasma associated with better outcomes than hyaluronic acid in knee osteoarthritis. Platelet-rich plasma might prolong the time to arthroplasty and provide a valid therapeutic option in selected patients with knee osteoarthritis not responding to conventional treatments. Further larger studies are needed to validate this promising treatment modality.