Arthroscopic stabilization for atraumatic shoulder instability: minimum two-year outcomes

Background: Atraumatic shoulder instability (type II glenohumeral instability) poses a unique challenge in management, with limited historical evidence supporting surgical intervention. This study evaluates outcomes of arthroscopic inferior capsular shift for type II instability in a specialized tertiary unit. Methods: A retrospective analysis of 72 shoulders in 70 patients undergoing arthroscopic inferior capsular shift between 2013 and 2017 was conducted. Inclusion criteria included atraumatic recurrent instability with a minimum follow-up of two years. Patients with traumatic or structural instability were excluded. Pre-operative and post-operative patient-reported outcome measures, recurrence rates, and predictors of recurrence were analyzed. Results: The cohort had a mean age of 27.4 years and included 46 females. At a mean follow-up of 2.7 years, significant improvements were observed in pain scores (7.3-2.7), Stanmore Percentage Of Normal Shoulder Assessment (43.8%-71.6%), and Oxford Shoulder Scores (29.6-39.1). Despite these improvements, 39% of patients reported recurrent instability, with 8.5% requiring revision surgery. Recurrence was more common in females and patients under 30 years of age, while hypermobility (Beighton score ≥5) was not predictive of outcome. Discussion and Conclusion: Arthroscopic inferior capsular shift demonstrated substantial functional and pain improvements but was associated with a higher-than-expected instability recurrence rate. Predictors of recurrence included younger age and female gender. These findings highlight the need for patient-specific surgical decision-making and thorough pre-operative counseling. Arthroscopic inferior capsular shift has been shown to be effective for improving pain and function in type II instability in patients recalcitrant to other management options. Despite this, patients should be counseled regarding the elevated risk of recurrence, especially younger females under 30 years.