Abstract
Purpose
The presence of a Hill-Sachs lesion is a major contributor to failure of surgical intervention following anterior shoulder dislocation. The relationship between lesion size, measured on pre-operative MRI, and risk of recurrent instability after surgery has not previously been defined.
Hypothesis: We hypothesized that the size of Hill-Sachs lesions on pre-op MRI would be greater among patients who failed soft tissue stabilization when compared to patients who did not fail. We also hypothesized that the existence of a glenoid lesion would lead to failure with smaller Hill-Sachs lesions.
Method
Nested case-control analysis of 114 patients was performed to evaluate incidence of failure after soft tissue stabilization. Successful follow-up of at least 24 months was made with 91 patients (80%). Patients with recurrent instability after surgery were compared to randomly selected age and sex matched controls in a 1:1 ratio. Pre-operative sagittal and axial MRI series were analyzed for presence of Hill-Sachs lesions, and maximum edge-to-edge length and depth as well as location of the lesion related to the bicipital groove (axial) and humeral shaft (sagittal) were measured.
Results
Of 91 patients included in analysis, 77 (84.6%) had identifiable Hill-Sachs lesions. 32 patients (35.2%) suffered from failure of soft tissue stabilization (redislocation 22.0%; subjective instability 13.2%). Ten of these patients (11.0%) underwent further surgery. When comparing the age and sex matched failure and control groups, statistically significant differences in unadjusted data were found for axial edge-to-edge length (p = 0.01), axial depth (p = 0.01), and sagittal edge-to-edge length (p = 0.04), with larger sized lesions found in the failure group (Figure 1). Differences trended towards significant for sagittal depth and angle from the bicipital groove.
Conclusion
In this retrospective case-control study, humeral head defect size was positively correlated with recurrent instability after soft-tissue stabilization. Larger Hill-Sachs lesions, as measured on pre-op MRI, were found in patients who failure surgical intervention when compared to patients who did not fail. These data and future studies may help determine pre-operative clinical guidelines for the treatment of anterior shoulder dislocation.
