Summary
The aim of this study was to investigate the prevalence of Hill-Sachs lesions and bony Bankart lesions in both dislocation and subluxation.Hill-Sachs lesions were observed in approximately 74.5% of subluxation, and bony Bankart lesions were observed in 33.9% of dislocation.
Abstract
Purpose
While shoulder dislocation requires manual reduction, shoulder subluxation has been classically defined as one that does not require a manual reduction maneuver. It is well known that bony defects of the glenoid and the humeral head are common injuries associated with anterior shoulder instability, but there are few reports comparing the prevalence of these lesions between dislocation and subluxation. The aim of this study was to investigate the prevalence of Hill-Sachs lesions and bony Bankart lesions in both dislocation and subluxation.
Method
The subjects were 180 shoulders of patients who visited our hospital due to shoulder dislocation or subluxation and underwent 3D-CT imaging. Subluxation was defined as one that does not require a manual reduction maneuver. The presence of Hill-Sachs lesions and bony Bankart lesions was evaluated using CT imaging, and the incidence rates and associations between the two lesions were investigated in three groups: dislocation-only (dislocation group), subluxation-only (subluxation group), and mixed dislocation and subluxation (mixed group). Statistical analysis was conducted using cross-tabulation of binary variables and trichotomous variables with multiple comparisons.
Result: In total, the dislocation group accounted for 56 shoulders (31.1%), the subluxation group for 98 shoulders (54.4%), and the mixed group for 26 shoulders (14.4%). Hill-Sachs lesions were observed in 148 shoulders (82.2%), and bony Bankart lesions in 66 shoulders (36.7%). The both lesions was seen in 57 shoulders (31.6%), while neither both lesion was observed in 23 shoulders (12.7%). Hill-Sachs lesions were present in 51 shoulders (91.1%) in the dislocation group, 73 shoulders (74.5%) in the subluxation group, and 24 shoulders (92.3%) in the mixed group. Bony Bankart lesions were found in 19 shoulders (33.9%) in the dislocation group, 31 shoulders (31.6%) in the subluxation group, and 16 shoulders (61.5%) in the mixed group. Significant differences were observed in the incidence of Hill-Sachs lesions between the dislocation group and the subluxation group, but no significant difference was observed between the mixed group and the other two groups. Regarding bony Bankart lesions, a significant difference was observed between the subluxation group and the mixed group, but no significant difference was observed between the dislocation group and the other two groups.
Discussion
Hill-Sachs lesions are believed to occur primarily in cases of complete dislocation, and in this study, they were significantly more prevalent in the dislocation group (91.1%). However, they were also observed in approximately 74.5% of the subluxation group. Bony Bankart lesions are commonly associated with subluxation, but no significant difference was observed between the dislocation and subluxation groups.
Conclusion
Hill-Sachs lesions were observed in approximately 74.5% of subluxation, and bony Bankart lesions were observed in 33.9% of dislocation.