ISAKOS: 2019 Congress in Cancun, Mexico
ISAKOS

2019 ISAKOS Biennial Congress ePoster #1847

 

Variations in Glenoid Bony Morphology May Predict Recurrent Instability After Arthroscopic Bankart Repair

Ravi S. Vaswani, MD, Pittsburgh, PA UNITED STATES
Andrew Sheean, MD, San Antonio, TX UNITED STATES
Gregory Gasbarro, MD, Pittsburgh, PA UNITED STATES
Christopher Como, BSE, Pittsburgh, PA UNITED STATES
Elan J. Golan, MD, Pittsburgh, PA UNITED STATES
Mitchell Fourman, MD, Pittsburgh, PA UNITED STATES
Andrew Wilmot, MD, Pittsburgh, PA UNITED STATES
Camilo Borrero, MD, Pittsburgh, PA UNITED STATES
Albert Lin, MD, Pittsburgh, PA UNITED STATES

UPMC, Pittsburgh, PA, UNITED STATES

FDA Status Not Applicable

Summary

Variations in bony morphology may help predict recurrent instability after shoulder stabilization.

Abstract

Introduction

The risk factors that lead to failure of bony Bankart stabilization are not completely understood. Variations in bony anatomy may be a significant risk factor for failure of stabilization surgery and could help explain the etiology of recurrent dislocations. Identifying these variations could help guide surgical decision making. The aim of this study was to develop

Method

to quantify bony morphology and measure glenoid and humeral head volume on MRI to identify risk factors for failure after Bankart repair. We hypothesized that the ratio of humeral head to glenoid volume and radius of curvature would be greater in patients who failed stabilization surgery.

Methods

This was a retrospective case-control study was performed of 289 patients from 2005-2015. Inclusion criteria were primary anterior arthroscopic shoulder stabilization, no prior shoulder surgery, and traumatic etiology. Exclusion criteria were posterior labral pathology, multidirectional instability, connective tissue disorder, or concomitant rotator cuff pathology. Surgical failure was defined as a redislocation event and these cases were compared 1:2 to an age- and sex-matched control without recurrent instability. Demographic data was obtained by chart review. Pre-operative MR arthrograms were analyzed by two trained reviewers. Vitrea software was utilized to measure humeral head and glenoid volume and radius of curvature on axial, coronal, and sagittal T1 sequences to obtain a three-dimensional model from which the volume was measured. Fisher exact and the student t test were used for statistical analysis with significant defined as p < 0.05.

Results

109 patients met the inclusion criteria. 36 patients (cases) experienced a redislocation event (12%) with an average follow-up of 30.3 months. There was no difference between groups with regard to age (p = 0.99), sex (p = 1.00), contact sports (p = 0.79), overhead athletes (p = 0.19), or throwers (p = 0.34). Lateral decubitus positioning (p = 0.12) and number of anchors for repair (p = 0.95) were also similar. The humeral head (67.8 ml vs 62.3 ml, p =0.13) and glenoid volume (13.7 ml vs 13.0 ml, p=0.42) were similar between the two groups, as was the ratio of the two (5.1 vs 4.9, p=0.30). The ratio of the radius of curvature of the humeral head to the glenoid was similar between the two groups (1.1 vs 1.1, p=0.11). The radius of curvature of the glenoid was the glenoid was slightly larger in the case group compared to the control group (23.8 vs 22.6, p=0.02).

Conclusion

In this study we present a novel method of quantifying the bony morphology that can help surgeons identify risk factors for redislocation after Bankart repair. The results show that glenoid size may predispose patients to failure of surgical stabilization.