Dynamic Anterior Stabilization Shows Glenohumeral Kinematics Closer to Native Motion to Isolated Bankart Repair: A Dual Fluoroscopic Imaging Study.

Abstract

To evaluate the effects of Bankart repair (BR) augmented with dynamic anterior stabilization (DAS) on in vivo glenohumeral kinematics in the treatment of anterior shoulder instability (ASI) and to determine its comparative effectiveness with isolated BR. Patients who underwent either BR alone (BR group) or BR augmented with DAS (DAS group) for treating ASI patients with <15% glenoid bone loss between May 2021 and December 2022 were enrolled. At 2-year follow-up, in vivo glenohumeral kinematics were quantified using a dual-fluoroscopic imaging system during the apprehension test and scapular abduction. Glenohumeral translations in the superior-inferior (S-I) and anterior-posterior (A-P) directions were compared between operative and contralateral shoulders. Eight patients were included in each BR and DAS group for final analysis, with comparable baseline characteristics between groups. During the apprehension test, the humeral head in BR shoulders were positioned significantly more anterior than that in contralateral shoulders during high external rotation angles of 80° (1.15 mm vs. -0.56 mm, P = .012) and 90° (1.81 mm vs. -0.27 mm, P = .001). In the DAS group, no significant differences were detected between bilateral shoulders in A-P translations at any external rotation angles (all P > .169). During scapular abduction, neither group showed significant inter-shoulder differences in A-P or S-I translations (all P > .262). For ASI patients with subcritical glenoid bone loss, isolated BR failed to restore kinematics to normal, as evidenced by the residual anterior humeral translation during terminal external rotation of the apprehension test. With additional DAS augmentation, the kinematic profile more closely approximated native shoulder motion, characterized by more centered A-P translation and preserved physiologic S-I movement. DAS augmentation produced favorable changes in select glenohumeral kinematic parameters, suggesting a potential biomechanical benefit when added to BR. Long-term investigations are required to determine whether these early kinematic findings translate into improved clinical outcomes.