Poster 175: Beach Chair Versus Lateral Decubitus Positioning for Primary Arthroscopic Posterior Shoulder Stabilization

OBJECTIVES: There are no studies that directly compare beach chair (BC) versus lateral decubitus (LD) position for arthroscopic treatment of posterior instability. In the few systematic reviews evaluating BC vs. LD, no difference had been demonstrated in regard to recurrence and revision rates. Additionally, bone loss was not accounted for in the recurrence rate. The purpose of this study is to identify predictors of shoulder instability recurrence and revision after posterior shoulder stabilization surgery in a young, high demand population and evaluate surgical position and glenoid bone loss as independent predictors of the outcomes of interest, recurrence and revision at short- and mid- term follow-up. METHODS: A consecutive series of 147 arthroscopic posterior stabilization procedures were performed by sports medicine certified and fellowship trained orthopaedic surgeons from 2005-2019 in either the BC or LD position. Patients were included if they underwent an isolated primary arthroscopic posterior capsulolabral repair. Patients were excluded if concomitant anterior labral repair was performed at the time of surgery. Shoulders were additionally excluded if magnetic resonance imaging (MRI) was not available at the time of preoperative evaluation, or the patient was lost to follow up. All shoulders were evaluated for glenohumeral bone loss using the best-fit circle technique on the sagittal enface MRI. The primary outcomes of interest were recurrent instability and revision stabilization. Recurrent instability was defined as the presence of a recurrent pain limiting activities with physical exam consistent with recurrent posterior instability per clinical notes in the electronic medical record. Rates of recurrence and revision were calculated among the full cohort among patients with available 1-year or 5-year follow up. Patient and procedure characteristics were compared by BC or LD group using two sample t-tests or Chi-square tests. RESULTS: A total of 147 shoulders with a mean age of 22.6 years (4.82 SD) underwent isolated arthroscopic repair and were followed for a mean 6.93 (3.29 SD) years. The overall recurrent instability and revisions rates were 16% (23/147) and 12% (18/147), respectively. With respect to surgical position, there was no significant difference in recurrence or revision (p-value >0.05). With respect to patient age, anchor number, and bone loss there was no significant difference in recurrence or revision with respect to patient age (p-value >0.05). CONCLUSIONS: Among fellowship-trained orthopaedic surgeons, there was no difference in rates of recurrent instability and revision surgery after performing arthroscopic stabilization for isolated posterior shoulder instability in a high demand population in either the BC or LD position.