To investigate the early clinical effect of delayed intraarticular injection of platelet-rich plasma (PRP) for the treatment of rotator cuff tears after repair.

Ninety patients with rotator cuff tears were selected from May 2021 to December 2022 in Yancheng NO.1 People’s Hospital. According to random number table, the patients were divided into three groups: the delayed single-injection group (single-injection group), the delayed multiple-injection group (multiple-injection group) and the control group, 30 cases in each group. All the patients underwent single-row rotator cuff repair with small to large full-thickness rotator cuff tears. All three groups of patients took the same rehabilitation program after surgery. The single-injection group received a single dose intra-articular injection of PRP one month after arthroscopic surgery. The multiple-injection group received intra-articular injection of PRP once a week for three consecutive weeks at one month postoperatively, while the control group received a single dose intraarticular injection of PRP at the end of arthroscopic surgery. Visual analogue scale (VAS), Constant-Murley score (CMS) and University of California Los Angeles shoulder score (UCLA) were recorded before and three, six,12 months after arthroscopic surgery. The results were statistically analyzed by repeated measurement variance analysis. Any adverse event during follow-up was record. The rotator cuff retear rates were evaluated 12 months after surgery by MRI.

All the patients were followed up. There were no statistically significant differences in VAS, CMS or UCLA scores among the three groups before surgery (F=0.077, 0.185, 1.269, all P>0.05). The VAS scores of the three groups after surgery were lower than those before surgery, and the CMS and UCLA scores after surgery were higher than those before surgery; VAS scores at three, six and 12 months after surgery in the multiple-injection group were significantly lower than those in the control group (I-J=-0.933, -0.700, -0.833, all P<0.05); the CMS and UCLA scores at three, six and 12 months after surgery in the multiple-injection group were significantly higher than those in the control group (I-J=5.100, 4.367, 3.600, all P<0.05; I-J=4.367, 1.600, 3.300, all P<0.05). The CMS scores at six and 12 months and the UCLA scores at six and 12 months after surgery in the multiple-injection group were significantly higher than those in the single-injection group (I-J=2.533, 2.267, both P<0.05; I-J=2.933, 1.600, both P<0.05). No wound swelling, exudation, blood vessel and nerve injury occurred in the three groups. There was no statistically significant difference in the rate of rotator cuff retear among the three groups (P>0.05).

Delayed injection of PRP after rotator cuff repair is a safe and effective method in treatment of rotator cuff tears, which could relieve the postoperative pain and improve shoulder function.