Bony Bankart lesions exceeding 20% of glenoid width are common and show gender-based anatomical differences: A radiological study of 239 patients.

INTRODUCTION/

OBJECTIVES

Bony Bankart lesions are anterior glenoid rim fractures associated with anterior shoulder dislocation and can increase the risk of recurrent instability, particularly in cases of fragment resorption or malpositioned healing. Despite their clinical significance, few large-scale radiological studies have detailed the fragment characteristics, displacement patterns, and associated bipolar lesions. The objective of this study was to describe fragment morphology, displacement, and related shoulder parameters using computed tomography (CT) imaging.

METHODS

This retrospective cohort study included 239 patients with isolated bony Bankart injuries identified via the Swedish Fracture Register between 2012 and 2019. All patients underwent CT imaging. Standardized linear measurement techniques were used to assess fragment size, displacement (inferior migration, diastasis, and step-off), Hill-Sachs lesion characteristics, glenoid version, and glenohumeral subluxation index.

RESULTS

The mean bony Bankart fragment size was 6.5 ​mm, representing 21.8% of the glenoid width. While absolute fragment size was similar between sexes, it accounted for a significantly larger portion of the glenoid surface in females (p ​= ​0.008). Fragment displacement parameters showed no sex-based differences. Hill-Sachs lesions were present in 61% of patients and were significantly larger in males (p ​= ​0.007), though relative to humeral head diameter, differences were not significant. A consistent ratio of glenoid-to-humeral head diameter (∼66-67%) was observed across sexes.

CONCLUSION

Bony Bankart lesions frequently involve more than 20% of the anterior glenoid, particularly in female patients due to anatomical size differences. CT-based linear measurements provide valuable data for analyzing clinically significant critical bone loss in cases of bony Bankart injuries. The consistent glenoid-to-humeral head diameter ratio may aid surgical planning in shoulder reconstructive procedures.

LEVEL OF EVIDENCE: Level IV, diagnostic study.