Hill-Sachs Lesion Size Is Not Associated With Chronicity of Anterior Shoulder Instability But Is Larger After Anterior Shoulder Dislocation Versus Subluxation.

PURPOSE: To evaluate preoperative factors associated with Hill-Sachs lesion (HSL) size at the time of imaging, including chronicity, number, and type (dislocation vs subluxation) of prior anterior shoulder instability events. METHODS: All patients undergoing arthroscopic Bankart repair between 2007 and 2023 were retrospectively reviewed. Exclusion criteria included age <14 years, revision surgery, glenoid bone loss >20%, unavailable magnetic resonance imaging, and lack of HSL. Patients were grouped based on chronicity of instability (acute ≤6 months vs chronic >6 months), 1 versus multiple prior instability events, and dislocation versus subluxation. HSL width and length were measured on axial and sagittal magnetic resonance imaging, respectively. HSL area (recorded in mm2) was calculated as HSL width time length. Imaging variables were compared between groups, and multivariable regression evaluated predictors of larger HSL area and smaller distance to dislocation (DTD). Significance was set to P < .050. RESULTS: After exclusion criteria, 255 patients (age: 22 ± 8 years; 24% female) were included for analysis. There was no association between acute versus chronic anterior shoulder instability and HSL width (11.6 vs 12.4 mm; P = .196), length (16.4 vs 16.7 mm; P = .521), or area (201.6 vs 215.7 mm2; P = .154). Patients who experienced dislocation versus subluxation had larger HSL length (16.7 vs 13.4 mm; P < .001) and HSL area (201.9 vs 150.7mm2; P = .012). Female sex (B: -74.5; P = .001) and glenohumeral dislocation (B: 49.5; P = .037) were predictors of smaller and larger HSL area, respectively, whereas chronic anterior shoulder instability was a predictor of DTD < 8 mm (odds ratio: 2.2; P = .008). CONCLUSIONS: Chronic anterior shoulder instability did not influence HSL size at the time of imaging but was found to be a predictor of DTD < 8 mm. Conversely, glenohumeral dislocation was a significant predictor of larger HSL area. This indicates that HSL size may be influenced more by type of instability event, whereas DTD may be more influenced by chronicity of anterior shoulder instability. LEVEL OF EVIDENCE: Level III, retrospective cohort study.