Platelet-rich plasma injection in the treatment of patellar tendinopathy: a systematic review and meta-analysis

Purpose The objective of the study was to assess the efficacy of autologous platelet-rich plasma (PRP) injections in the treatment of patellar tendinopathy. Methods The PubMed, MEDLINE, EMBASE, CINAHL, and Cochrane Central Register of Controlled Trials databases were searched for clinical trials which compared PRP injection with other 'active treatment' interventions ('Non-PRP' injection and 'No-injection' treatments) or 'No-active treatment' interventions. Randomized and non-randomized clinical trials that had been published up to 15 November 2021, were included in the meta-analysis. The primary outcome, pain relief, was measured on a 'visual analog scale.' Secondary outcomes were knee functional activities and quality of life (QoL). The PRISMA guidelines were followed throughout the study. Results Eight comparative studies were identified for inclusion in the meta-analysis. Assessment of these studies revealed that there were no significant differences in pain relief, functional outcomes, and QoL in the short, medium, and long term between PRP injection and Non-PRP injection interventions. Similarly, comparison of PRP injection to the No-active treatment intervention showed no differences in short- and medium-term pain relief. However, when PRP injection was compared to the No-injection treatment intervention extracorporeal shock wave therapy (ECWT), the former was found to be more effective in terms of pain relief in the medium term (mean difference [MD] - 1.50; 95% confidence interval [CI] - 2.72 to - 0.28) and long term (MD - 1.70; 95% CI, - 2.90 to - 0.50) and functional outcomes in the medium term (MD 13.0; 95% CI 3.01-22.99) and long term (MD 13.70; 95% CI 4.62-22.78). Conclusions In terms of pain relief and functional outcomes, the PRP injection did not provide significantly greater clinical benefit than Non-PRP injections in the treatment of patellar tendinopathy. However, in comparison with ESWT, there was a significant benefit in favor of PRP injection.