ObjectiveTo evaluate the clinical effectiveness and safety of platelet-rich plasma (PRP) in the arthroscopic repair of full-thickness rotator cuff injury.MethodsRelevant randomized controlled trials were identified from Cochrane Library, PubMed, Embase, China Biology Medicine Database, Chongqing VIP Database, China National Knowledge Infrastructure, and Wanfang Database (from the dates of establishment to September 2020). A systematic review was performed to compare the short-term and mid-term retear rates, the scores of the University of California at Los Angeles (UCLA) Shoulder Rating Scale, and the scores of Visual Analogue Scale (VAS) between the two groups. Analyses were conducted using RevMan 5.2.0 software.ResultsNine studies with low heterogeneity were included in the meta-analysis involving 610 cases (305 in the PRP group and 305 in the control group). There were significant differences in the short-term retear rate [relative risk (RR)=0.29, 95% confidence interval (CI) (0.13, 0.65), P=0.003], the short-term and the mid-term UCLA scores [standardized mean difference (SMD)=0.35, 95%CI (0.14, 0.56), P=0.000 9; SMD=0.87, 95%CI (0.53, 1.21), P<0.000 01], the short-term and the mid-term VAS scores [SMD=−0.29, 95%CI (−0.51, −0.07), P=0.009; SMD=−0.35, 95%CI (−0.66, −0.03), P=0.03] between the two groups. There was no significant difference in the mid-term retear rate [RR=0.88, 95%CI (0.48, 1.63), P=0.69] or complication rate [RR=1.40, 95%CI (0.78, 2.54), P=0.26] between the two groups.ConclusionsPRP injection can effectively improve the clinical outcomes following arthroscopic repair of full-thickness rotator cuff tears, thus reducing the short-term retear rate, alleviating pain, and improving patients’ shoulder function.