Summary

Younger age, significant bone loss (either on the glenoid or humeral side), SLAP tear, and ligamentous laxity increase the likelihood of failure following an arthroscopic revision anterior stabilization.

Abstract

Introduction

Individuals that fail arthroscopic revision anterior stabilization (ARAS) procedures of the shoulder represent a unique and challenging patient population. To date, there have been few large studies that have investigated revision failure rates or identified variables that can influence clinical outcomes.[1] This study aims to determine the risk factors for recurrent shoulder instability following ARAS. We hypothesized that male gender, younger age, participation in contact sports, significant glenoid and/or humeral bone loss, ligamentous laxity, and worker’s compensation would increase the risk of revision failure.

Methods

Following Institutional Review Board approval, a retrospective chart review from January 1, 2005 to December 31, 2014 was performed to identify patients who underwent ARAS. Patients with posterior instability, multidirectional instability, or those that underwent concomitant rotator cuff repair were excluded. Failures were defined as recurrent dislocation or subluxation. Glenoid and humeral head bone loss was evaluated using the T1-weighted magnetic resonance arthrogram sequences. On oblique sagittal images, the best-fit circle method was used to measure glenoid bone loss. The Rowe scoring system was used on axial images to gauge humeral bone loss.[2] Chi-square test and logistic regression were used to assess the association between potential risk factors and revision failure.

Results

Overall 65 patients [age at revision = 26.1 (range, 15 – 57), 44 male] met inclusion criteria for this study. The mean follow-up time was 56.4 months. Failure following ARAS was seen in 27 patients (42%) with a mean time to failure of 27.2 months. Statistically significant predictors of failure included age less than 22 years (OR = 2.80, p = 0.045), glenoid bone loss (OR = 5.20, p = 0.004), humeral head bone loss OR = 3.87, p = 0.016), SLAP tear (OR = 3.67, p = 0.024), and ligamentous laxity (OR = 3.88, p = 0.024). Male gender, contact sports, and workers’ compensation were not identified as risk factors for failure.

Discussion

The failure rate following ARAS in this is study is higher than the 12.7% currently reported in the literature.[1] Younger patients with bone defects (glenoid and/or humeral) were are at a higher risk of failure after revision surgery. A possible explanation is that the loss of the glenoid surface reduces its concavity and arc length, contributing to instability. From the humeral perspective, increasing size of Hill-Sachs lesions has been shown to decrease the resistance to dislocation and our findings are also consistent with the recent concepts of “off-track” lesions.[3, 4] The risk factors identified in our study highlight the importance of patient selection when considering arthroscopic versus open stabilization in the revision setting.
References: [1] Abouali et al. Arthroscopy. 2013;29:1572-78. [2] Rowe et al. JBJS. 1984;66(2):159-68. [3] Kaar et al. Am J Sports Med. 2010;38(3):594-99. [4] Giacomo et al. Arthroscopy. 2014;30(1):90-8.