Comparison of efficacy of single PRP injection with placebo and multiple PRP injection in the treatment of rotator cuff syndrome: A double-blind randomized controlled trial

Objective: In our study, we aimed to evaluate the efficacy of subacromial single PRP injection versus placebo and multiple PRP injections on pain, quality of life, shoulder function and muscle strength in the treatment of patients with shoulder pain who have rotator cuff tendinopathy and/or partial tear of the supraspinatus. Materials and Methods: A total of 80 patients with rotator cuff syndrome, aged 29-65 years, 27 patients in the sham PRP+exercise group, 26 patients in the single PRP+exercise group and 27 patients in the multiple PRP+exercise group were included in the study. Patients were randomly divided into three groups. The single PRP group received four ml of PRP injection into the subacromial space under ultrasound guidance once, and the multiple PRP group received four ml of PRP injection into the subacromial space under ultrasound guidance twice at three-week intervals. For the sham PRP group, the same amount of blood was collected and the same waiting time was given, but four ml of 0.9% saline was injected into the subacromial space under ultrasound guidance with the same method. All injectors were covered with non-transparent tape to ensure blinding. All groups were taught a physiotherapy programme including standard shoulder ROM, stretching and strengthening exercises by an experienced physiotherapist and were asked to perform at least 20 min every day. Demographic data of the patients were recorded. The evaluation parameters included symptom duration, passive and active shoulder range of motion (ROM), Visual Analogue Scale (VAS), Constant Murley Score (C-MS), Shoulder Pain and Disability Index (OADI), SF-36 Quality of Life Assessment Questionnaire and peak torque muscle strength measurement at 120, 180 and 210 degrees of velocity in internal and external rotation of the shoulder with isokinetic dynamometer. The evaluations were performed before treatment (T0), four weeks after treatment (T1) and 12 weeks after treatment (T2). Results: The mean age of the study participants was 49.26±9.37 years, 44 (55%) were female and 36 (45%) were male. In all three treatment groups, there were significant statistical differences in active ROM, VAS, C-MS and OADI scores at 4 weeks (T1) and 12 weeks (T2) post-treatment compared to pretreatment (T0) (p<0.05), but the improvement in the single PRP and multiple PRP groups was more significant at 4 weeks (T1) and 12 weeks (T2) post-treatment compared to the sham PRP group (p<0.05). In the sham PRP group, a significant statistical difference was found in SF-36 physical function, physical role limitation, emotional role limitation, social function and pain sub-parameters at the 12th week (T2) post-treatment control compared to pretreatment (T0) (p<0.05). In the single PRP and multiple PRP groups, significant improvement was observed in all sub-parameters of SF-36 at 4 weeks (T1) and 12 weeks (T2) post-treatment compared to pretreatment (T0) (p<0.05). In the intergroup evaluation, it was observed that the improvement in all sub-parameters of SF-36 was more significant in the single PRP and multiple PRP groups compared to the sham PRP group (p<0.05), but no significant statistical difference was found between the single PRP and multiple PRP groups (p>0.05). In muscle strength assessment with isokinetic dynamometer, external rotation 120°/sec, 180°/sec and 210°/sec peak torque measurements in sham PRP group, internal rotation 120°/sec, 210°/sec, external rotation 120°/sec, 180°/sec and 210°/sec peak torque measurements in single PRP group, In the multiple PRP group, a significant statistical difference was found in peak torque measurements of all isokinetic sub-parameters (internal rotation 120°/sec, 180°/sec and 210°/sec, external rotation 120°/sec, 180°/sec and 210°/sec) (p<0,05). In the intergroup comparison of muscle strength with isokinetic dynamometer, a more significant improvement was observed in the internal rotation 180°/sec and 210°/sec peak torque measurements in the multiple PRP group compared to the sham PRP group at the 12th week (T2) control (p<0.05). External rotation 120°/sec peak torque measurements at the 12th week (T2) control showed more significant improvement in single PRP and multiple PRP groups compared to sham PRP group (p<0.05). Conclusion: In rotator cuff syndrome, ultrasound-guided single PRP injection into the subacromial space and multiple PRP injections administered twice three weeks apart significantly improve pain, range of motion, functionality and quality of life in the short and medium term compared to placebo. Single and multiple PRP injections are more effective than placebo in increasing muscle strength assessed by isokinetic dynamometer in the medium term. Keywords: Rotator cuff syndrome, PRP injection, Supraspinatus muscle, Subacromial bursa