Surface electromyographic evaluation of scapular dyskinesia in patients with rotator cuff tears

Wang Xuepeng; He Yong

doi:10.12307/2026.096

Abstract：BACKGROUND:Rotator cuff tears are a prevalent condition affecting the shoulder joint,which can substantially diminish a patient's quality of life.Surface electromyography is a diagnostic technique that captures the electrophysiological signals of muscles during movement.Most of its studies have focused on special populations such as athletes and hemiplegic patients,but its use in patients with rotator cuff tears is still rare. OBJECTIVE:To compare the differences in the movement patterns of the muscles around the scapula between normal subjects and patients with rotator cuff tears using surface electromyography and to investigate the pathogenetic mechanisms of scapular dyskinesia in patients with rotator cuff tears,thereby providing a basis for the establishment of clinical rehabilitation protocol. METHODS:From September 2021 to February 2023,40 patients with rotator cuff tears who met the enrolled criteria at Guanghua Hospital affiliated to Shanghai University of Chinese Medicine were included in the trial group,and a control group without shoulder disease(n=40)was set.Demographic and clinical data were obtained using surface electromyography.Using the maximal voluntary isometric contraction(MVIC)method,the%MVIC of the upper trapezius,middle trapezius,lower trapezius,and serratus anterior muscles was measured during shoulder flexion,abduction,and external rotation at the side.Each movement was tested thrice,and the average%MVIC ratios of upper trapezius/lower trapezius,upper trapezius/middle trapezius,and upper trapezius/serratus anterior were calculated for intergroup comparison. RESULTS AND CONCLUSION:Compared with the control group,the trial group showed significantly higher%MVIC ratios of upper trapezius/lower trapezius,upper trapezius/middle trapezius,and upper trapezius/serratus anterior during shoulder flexion,abduction,and external rotation at the side(all P<0.05).To conclude,the mechanism of scapular dyskinesis in patients with rotator cuff tears may involve overactivation of the trapezius and serratus anterior muscles,resulting in movement imbalance.