Efficacy of platelet-rich plasma injection in the treatment of frozen shoulder: A systematic review and meta-analysis

BACKGROUND: Frozen shoulder (FS) is characterized by progressive shoulder pain and a limited range of motion. Recently, platelet-rich plasma (PRP) injection is a newly developed treatment option for patients with FS and its efficacy needs to be examined. OBJECTIVE: By conducting a systematic review and meta-analysis, this study attempted to evaluate the efficacy of PRP injection in the treatment of patients with FS. METHODS: PubMed, EMBASE, Web of Science, Elsevier, The Cochrane Library, WanFang Data and CNKI databases were searched up to May 31, 2020. This study included randomized controlled trials as well as prospective cohort studies. Two reviewers independently screened the title, abstract and full text in order to extract data from qualified studies. The main outcome was pain visual analogue score (VAS) while the secondary outcome was range of motion (ROM) of the shoulder joint that consists of four parts: internal rotation, flexion, external rotation and abduction. RESULTES: Three randomized controlled trials and one prospective cohort study met the inclusion criteria. Accordingly, a total of 359 cases were analyzed and followed up to 3 months. The control group included corticosteroids (CS), ultrasound therapy, and stellate ganglion block. Compared to other groups, VAS was statistically significant after 1 month and 3 months of treatment (SMD: -0.46, 95% CI: -0.75 to -0.18, P = 0.002; I-2 = 43.2%), (SMD: -0.87, 95% CI: -1.23 to -0.50, P = 0.00, I-2 = 61.9%). Compared to the control group, only flexion of the patients treated with PRP demonstrated no significant improvement at 1 month, whereas internal rotation, flexion, external rotation and abduction of the shoulder were found to be improved following 3 months of treatment. CONCLUSIONS: The corresponding findings illustrate that compared to other non-operative treatments, local injection of PRP can effectively improve pain and shoulder motion in patients with FS. However, due to the short follow-up time and limitations regarding the quantity and quality of studies, the above conclusions require further elucidation by performing additional high-quality studies.