Mid‐frequency electrical muscle stimulation during immobilization may prevent early deltoid muscle atrophy and promote early strength recovery after arthroscopic rotator cuff repair

Abstract Purpose To evaluate the effect of mid‐frequency electrical muscle stimulation (MFEMS) applied to the deltoid muscle during immobilization period on preventing muscle atrophy and enhancing strength and function after arthroscopic rotator cuff repair (ARCR). Methods Patients were divided into two groups: 45 underwent ARCR using the MFEMS device during the immobilisation period after surgery (MFEMS group) and 43 underwent ARCR without using the MFEMS device (control group). The same rehabilitation protocol was applied to both groups except for MFEMS administration. Magnetic resonance imaging (MRI) was checked three times preoperatively, at the brace‐weaning period (when the MFEMS treatment was finished), and at 6 months after surgery. The change of deltoid muscle volume from MRI was measured using in‐house developed software. Pain visual analogue scale (VAS), range of motion (ROM), shoulder strength ratios and various functional scores were evaluated at each follow‐up until 12 months, and the healing failure rate was assessed. Results At the brace‐weaning period, significantly different deltoid volume changes were observed (0.42% muscle volume decrease in the MFEMS group vs. 10.66% decrease in the control group, p = 0.009). In addition, the strength ratios of the abductor at 3 months (0.70 ± 0.15 vs. 0.63 + 0.16) were significantly higher in the MFEMS group compared with the control group (all p = 0.039). Further, the Constant score was significantly higher in the MFEMS group (87.89 vs. 84.26; p = 0.041). There were no differences in the pain VAS, shoulder ROM or healing failure rate (three in the MFEMS group and four in the control group) between groups (all p > 0.05). Conclusions The application of the MFEMS during immobilization period after ARCR effectively prevented early post‐operative deltoid muscle atrophy and accelerated early recovery of shoulder muscle strength. However, its long‐term impact on functional outcomes remains unclear and warrants further investigation. Level of Evidence Level III, retrospective comparative study.