The investigation of the effect of humeral head depressor muscle co-activation training on functional outcomes in patients undergoing arthroscopic shoulder surgery after medium-sized rotator cuff muscle tear

Several clinical trials have investigated the effects of the humeral head depressor muscle co-activation training on glenohumeral joint dysfunction. However, evidence is still lacking to support the efficacy of this program for the patients undergoing arthroscopic rotator cuff repair (ARCR) after medium-sized rotator cuff (RC) muscle tear. In this context, the aim of this study was to evaluate the effects of humeral head depressor muscle co-activation training on functional outcomes in patients undergoing ARCR after medium-sized RC muscle tear. Twenty-seven individuals were included in this study. One participant was excluded from the study before randomization. A total of twenty-six participants were randomly divided into two groups as the treatment group (n=13) and control group (n=13). Conservative training of both groups were conducted by the same researcher. In addition to the conservative program, humeral head depressor muscle co-activation training for teres major, latissimus dorsi and pectoralis major muscles was performed for the treatment group. The EMG-Biofeedback (Chattanooga Group Inc., Chattanooga, TN), a neuromuscular-based training tool, was used for co-activation training. Co-activation of these muscles was requested during glenohumeral joint exercises. Participants were assessed in terms of pain (Visual Analog Scale), range of motion (Universal Goniometer), and functional scores (Disabilities of the Arm, Shoulder, and Hand Questionnaire; Revised Oxford Shoulder Score; Modified Constant-Murley Score; Western Ontario Rotator Cuff Index) both pre- and post-treatment blindly to the groups. Due to the some problems during the follow-up period, 24 participants were analyzed. Both programs were found to be effective in the intra-group comparisons in terms of all measurements (p<.05). In terms of time and group*time interactions, the improvement in examined variables were greater in the treatment group compared to the control group except internal rotation range of motion (p<.05). Humeral head depressor muscle co-activation training is an effective choice in the treatment of the patients undergoing ARCR after medium-sized RC muscle tear according to the results of this study. Decrease of net abduction torque and increase of glenohumeral contact force improve functional scores.