Cross-education effects on shoulder rotator muscle strength and function after shoulder stabilization surgery: a randomized controlled trial

Hypothesis This study aimed to investigate the effects of cross education (CE) on rotator cuff (RC) muscle strength recovery and shoulder function in patients who underwent arthroscopic anterior shoulder stabilization surgery. Methods Twenty-eight patients who underwent shoulder stabilization surgery were included in the study (age, 25 ± 6 years; body mass index, 24.8 ± 3.6 kg/m2). The patients were randomly divided into either the CE group (n = 14) or the control group (n = 14). All patients received a standardized rehabilitation program until the end of the 12th postoperative week. The CE group also received isokinetic training of the nonoperative shoulder focusing on the RC muscles (twice a week, 3 sets of 10 repetitions). RC muscle strength was measured preoperatively and at 3 and 6 months postoperatively using an isokinetic dynamometer at 60°/s and 180°/s angular velocities. Shoulder function was assessed with the Closed Kinetic Chain Upper Extremity Stability Test and Y-Balance Test–Upper Quarter. Analyses of covariance were used for the statistical analyses. Results At 6 months postoperatively, at 60°/s angular velocity, there was higher internal rotator strength in the CE group (P = .02) and similar external rotator strength (P = .62) between the groups. At 180°/s angular velocity, both internal rotator strength (P = .04) and external rotator strength (P = .02) were higher in the CE group. The Closed Kinetic Chain Upper Extremity Stability Test (P = .47), Y-Balance Test–Upper Quarter (P = .95), and Western Ontario Shoulder Instability Index (P = .12) scores were similar between the groups at 6 months after surgery. Conclusions CE in the early period of postoperative rehabilitation following stabilization surgery improves RC strength recovery. However, it has no effect on functional outcomes. Integrating a CE program into the postoperative rehabilitation protocol may help to improve dynamic shoulder stability but not functional capacity. This study aimed to investigate the effects of cross education (CE) on rotator cuff (RC) muscle strength recovery and shoulder function in patients who underwent arthroscopic anterior shoulder stabilization surgery. Twenty-eight patients who underwent shoulder stabilization surgery were included in the study (age, 25 ± 6 years; body mass index, 24.8 ± 3.6 kg/m2). The patients were randomly divided into either the CE group (n = 14) or the control group (n = 14). All patients received a standardized rehabilitation program until the end of the 12th postoperative week. The CE group also received isokinetic training of the nonoperative shoulder focusing on the RC muscles (twice a week, 3 sets of 10 repetitions). RC muscle strength was measured preoperatively and at 3 and 6 months postoperatively using an isokinetic dynamometer at 60°/s and 180°/s angular velocities. Shoulder function was assessed with the Closed Kinetic Chain Upper Extremity Stability Test and Y-Balance Test–Upper Quarter. Analyses of covariance were used for the statistical analyses. At 6 months postoperatively, at 60°/s angular velocity, there was higher internal rotator strength in the CE group (P = .02) and similar external rotator strength (P = .62) between the groups. At 180°/s angular velocity, both internal rotator strength (P = .04) and external rotator strength (P = .02) were higher in the CE group. The Closed Kinetic Chain Upper Extremity Stability Test (P = .47), Y-Balance Test–Upper Quarter (P = .95), and Western Ontario Shoulder Instability Index (P = .12) scores were similar between the groups at 6 months after surgery. CE in the early period of postoperative rehabilitation following stabilization surgery improves RC strength recovery. However, it has no effect on functional outcomes. Integrating a CE program into the postoperative rehabilitation protocol may help to improve dynamic shoulder stability but not functional capacity.