Poster 170: First-Time Anterior Shoulder Instability Events in Subluxators versus Dislocators: A Comparison of Clinical Presentation,Extent of Injury,and Revision

Abstract

Objectives:

The objective of this study was to characterize epidemiology and postoperative outcomes in subluxators and dislocators after a first-time anterior instability (FTAI) event. We hypothesized that subluxators would have a milder clinical presentation, lesser degree of pathology on imaging, and fewer anchors placed intraoperatively in comparison to dislocators.

Methods:

Surgically managed FTAI patients from a single institution between 2013-2020 were included. Exclusion criteria included multidirectional instability and recurrent instability. Demographics and surgical details were retrospectively collected. Instability was categorized into dislocation, in which another person reduced the shoulder, or subluxation, in which there was no documentation of another person reducing the shoulder. Labral tear location was determined using the clock method and labral tear size was determined by assigning 1 point to each hour around the clock for a maximum value of 12.

Results:

146 patients (97 subluxators, 79 dislocators) were available for analysis. There were no significant differences in baseline demographics. Rates of bony Bankarts were equivalent, but Hill-Sachs lesions were reported more in dislocators (88.1% vs. 52.6%, p<0.001). Table 1. Preoperative and postoperative ROM and strength was equivalent between cohorts. There was no difference in either labral total tear size or incidence of concomitant posterior or superior labrum tears. There was no difference in the number of anchors used, although remplissage was performed more in dislocators (18.9% for dislocators vs. 6.0%, p = 0.002). Revision rates were not significantly different between cohorts.

Conclusions:

Subluxators and dislocators had similar clinical presentations with no difference in the extent of injury except for greater frequency of Hill-Sachs lesions in dislocators with similar surgical outcomes. Given comparable injury characteristics, a tendency to bias subluxation events as “less severe” should be reconsidered. Further investigations may be necessary to determine demographic and anatomic predictive risk factors that influence outcomes between these two populations.