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

Abstract

To investigate the effects of cross-education on RC muscle strength recovery and shoulder function in patients with arthroscopic anterior shoulder stabilization surgery. Twenty-eight patients with shoulder stabilization surgery were included in the study (age: 25±6 years and body-mass index: 24.8±3.6 kg/m2). The patients were randomly divided into either cross-education (n=14) or control (n=14) groups. All patients received a standardized rehabilitation program until the end of the postoperative 12th week. The cross-education group also received an isokinetic training with the non-operated shoulder focusing on the RC muscles (twice a week, 3 sets of 10 repetitions). RC muscle strength was measured preoperatively and three, and six months postoperatively using an isokinetic dynamometer at 60°/sec and 180°/sec angular velocities. Shoulder function was assessed with Closed Kinetic Chain Upper Extremity Stability Test (CKCUEST) and Y-balance Test for Upper Quarter (YBT-UQ). Analyses of covariance were used for the statistical analyses. At the postoperative six months and at 60°/sec angular velocity, there was higher IR strength in the cross-education group (p=0.02) and similar ER strength (p=0.62) between the groups. At 180°/sec angular velocity, both IR (p=0.04) and ER (p=0.02) strength were higher in the cross-education group. The CKCUEST (p=0.47), YBT-UQ (p=0.95) and WOSI (p=0.12) scores were similar between the groups at six months after the surgery. Cross-education in the early periods of the postoperative rehabilitation following the stabilization surgery improves the RC strength recovery. However, it has no effects on the functional outcomes. Integrating the cross-education program to the postoperative rehabilitation may help to improve dynamic shoulder stability but not the functional capacity.