OBJECTIVE Partial-thickness rotator cuff tears have a high prevalence in older people. Treatment for such tears remains controversial. Platelet-rich plasma has recently attracted attention for treating partial-thickness rotator cuff tears, due to its regenerative characteristics. However, the results of application of platelet-rich plasma in non-operative treatments are unclear. The aim of this review is to evaluate the effects on shoulder
function improvement and pain relief of platelet-rich plasma injection in partial-thickness rotator cuff tears, at different follow-up times (3-6 weeks, 8-12 weeks, and more than 24 weeks after treatment) compared with placebo or corticosteroids. DESIGN A systematic review and meta-analysis. METHODS Several databases, including PubMed, EMBASE, and Cochrane, were searched. Eleven studies met the inclusion criteria for the meta-analysis. The quality of research was evaluated using the Cochrane risk-of-bias tool. The effectiveness of platelet-rich plasma was calculated as the difference between baseline measurements and post-injection outcomes. The standardized mean difference was used to compare different outcome scales or questionnaire measurements. Statistical analysis was performed using Stata 15.0. RESULTS The analysis included 11 studies, with a total of 641 patients (318 treated with platelet-rich plasma and 323 controls). Compared with placebo, platelet-rich plasma exhibited significantly better effects on shoulder function improvement and pain relief at all 3 follow-up times. Compared with other conservative treatments, platelet-rich plasma exhibited significantly better effects on shoulder function and pain relief at 8-12 weeks and at more than 24 weeks after treatment. CONCLUSION This review showed positive effects on shoulder function improvement and pain relief of the use of platelet-rich plasma in treating partial-thickness rotator cuff tears, especially in relatively late stages of follow-up (more than 8 weeks) after treatment.