Comparison of Core Muscle Asymmetry Using Spine Balance 3D in Patients with Arthroscopic Shoulder Surgery: A STROBE-Compliant Cross-Sectional Study

Background and Objectives: Joint immobilization after shoulder surgery can cause an imbalance in the periscapular muscles and affect the kinetic chain throughout the body. There is a difference in core muscle stability because of the asymmetry of the lower extremity muscles. However, the difference due to the asymmetry of the upper-extremity muscles has not been studied extensively. The purpose of this study is to investigate the effect of joint immobilization on the symmetry of the core muscles involved in proximal stability for distal mobility. Materials and Methods: Fifty-five patients who underwent arthroscopic shoulder surgery participated in this study. Core muscle asymmetry (CMA) was measured using a body tilt device. The evaluation variables were analyzed according to the surgical site based on the direction of the core muscle ratio and core muscle state ratio. Results: No differences in CMA were found based on the surgical site (p > 0.05). As a result of the additional subanalysis, significant differences in sex and postoperative day were established (p < 0.05). CMA was low during the intensive postoperative rehabilitation period. However, sex-related differences were greater in males than in females. Conclusions: The clinical results suggest that core muscle training is necessary to reduce CMA during rehabilitation after the immobilization period has elapsed.