The relationship between Hill-Sachs lesion and scapular morphology in anterior shoulder instability

Abstract Objective This study investigated the relationship between scapular morphological parameters (critical shoulder angle, glenoid inclination, and glenoid version) and Hill-Sachs lesion presence and size in anterior shoulder instability patients without critical glenoid bone loss (< 15%), using 3D computed tomography. Materials and methods Computed tomography (CT) images and arthroscopic records of 93 patients without critical glenoid bone loss who had anterior shoulder instability surgery were reviewed. 3D CT reconstructions were made using 3D Slicer software. Critical shoulder angle (CSA), glenoid inclination (GI), and glenoid version (GV) were measured, and their associations with HSL length (HSL-L), HSL width (HSL-W), HSL depth (HSL-D) and HSL area (HSL-A) were analyzed. Patients were grouped by HSL presence, and statistical analyses were conducted. Results HSLs were identified in 61 of 93 patients (32 HSL-negative). CSA was significantly higher in HSL-positive than HSL-negative patients (34.5 ± 2.9° vs 30.4 ± 1.7°, P < 0.001). Logistic regression showed CSA was independently associated with HSL presence ( P = 0.002; OR = 2.7). CSA above 32.1° showed 77.8% sensitivity and 83.7% specificity for HSL presence. CSA correlated with HSL-L and HSL-A, and GI positively correlated with HSL size parameters (HSL-L, HSL-W, HSL-D and HSL-A). HSL presence and size were independent of dislocation number, age, sex, and side. Conclusions HSL presence and size were associated with scapular morphology, with CSA independently predicting HSL presence at values above 32.1°. These findings apply to patients with anterior shoulder instability without critical glenoid bone loss (< 15%). CSA may serve as an ancillary parameter in stabilization surgery planning, particularly when choosing between Bankart repair and Bankart + remplissage.