Risk Factors for Recurrent Anterior Shoulder Instability after Arthroscopic Stabilization in Adolescent Athletes

Abstract

Objectives: Arthroscopic stabilization has become the preferred surgery for adolescent athletes with anterior instability without significant bone loss. Although successful for most patients, 10-40% will experience recurrent instability. The purpose of the current study was to compare a consecutive series of patients who had failed an arthroscopic stabilization to an age and gender matched cohort of patients who had no evidence of recurrent instability with a goal of identifying risk factors for future instability. Methods: A retrospective review was undertaken of all patients undergoing an arthroscopic shoulder stabilization for anterior instability between 2009 and 2016. Patients over the age of 18 years and those with underlying syndromes affecting the musculoskeletal system were excluded. Two patient cohorts were identified: (1) Patients with recurrent instability (frank dislocations or subluxations) after their arthroscopic stabilization; (2) An age and gender matched cohort of patients with no recurrent instability at a minimum of 2 years follow-up from surgery. Patient demographic, injury, radiographic, and surgical variables were recorded. In particular, bone loss measurements were performed on both the glenoid and humerus, and Hill-Sachs lesions were classified as “on-track” or ”off-track”. Variables at p<0.10 on univariate analysis were entered into a binary logistic multivariate regression analysis. Results: 35 patients were identified that failed an arthroscopic stabilization at a mean of 1.2 ± 1.0 years after their index surgery. A separate age and gender matched cohort of 35 patients was also identified with no symptoms of recurrent instability. Univariate analysis identified the following 4 risk factors for recurrent instability (glenoid bone loss > 10%, glenoid retroversion < 5◦, skeletal immaturity, and patients with more than one pre-surgical instability event). Collision sport participation, the presence and size of a Hill-Sachs deformity, and the glenoid track were not predictive of failure. Multivariate regression analysis revealed that loss of glenoid retroversion, skeletal immaturity, and a greater number of prior instability events best predicted future recurrence with two risk factors having a 3x increased risk and patients with all three risk factors having a 4x increased risk of recurrent instability after arthroscopic stabilization. Conclusion: Anterior glenoid bone loss, glenoid version, skeletal immaturity, and multiple pre-operative instability events are risk factors for failed arthroscopic stabilization in adolescent athletes with anterior instability. In the setting of multiple risk factors, patients and families should be counselled of the increased odds of surgical failure and other forms of surgical stabilization may need to be considered.