Summary

Equivalent outcomes may be anticipated with arthroscopic Bankart repair performed in the BC or LD position.

Abstract

Introduction

There are no studies that directly compare beach chair (BC) versus lateral decubitus (LD) position for anterior instability. In the only systematic review evaluating BC vs. LD, bone loss is not accounted for in the recurrence rate. The purpose of this is to identify predictors of shoulder instability recurrence and revision after anterior 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 641 arthroscopic Bankart stabilizations 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 anterior capsulolabral repair. Patients were excluded if concomitant labral repair and/or Remplissage procedures were 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 perfect circle technique on the sagittal en-face MRI as well as for bipolar lesions according to the on/off-track method of Diagacomo et al. Glenoid bone loss was grouped into three categories: <5%, 5-13.5%, and >13.5%. The primary outcomes of interest were recurrent instability and revision stabilization. Recurrent instability was defined as the presence of a recurrent subluxation and or dislocation event and/or the presence of a positive apprehension. Multivariable logistic regression models were used to assess the relationships of outcomes with age, position, glenoid bone loss group, and track.

Results

A total of 641 shoulders with a mean age of 22.3 years (SD 4.45) underwent isolated arthroscopic Bankart repair and were followed for a mean 6 years. The overall one-year recurrent instability and revisions rates were 3.3% (21/641) and 2.8% (18/641), respectively. At one-year, recurrent instability was observed in 2.3% (11/487) and 6.5% (10/154) of BC and LD shoulders. The five-year recurrent instability and revision rates were 15.7% (60/383) and 12.8% (49/383). At five-years, recurrent instability was observed in 16.4% (48/293) and 13.3% (12/90) of BC and LD shoulders.

When adjusted for age, position, and bone loss group, multivariable logistic regression modeling demonstrated surgical position was not associated with risk of recurrent instability after one-year (OR for LD vs BC = 1.39; p=0.56) and five-year (OR for LD vs BC=1.32, p=0.43) follow-up time periods. However, after five-year follow-up younger age at index surgery was independently associated with higher risk of recurrent instability: OR = 1.73 per SD (4.1 years) decrease in age (P<0.03)

After one-year and five-year follow-up time periods, surgical position results were similar in a separate multivariable logistic regression model of revision surgery as the dependent variable, when adjusted for age, branch, bone loss group, and track. After five year follow-up, only younger age at time of index surgery remained an independent risk factor for revision: OR 1.68 per SD (4.1 years) decrease in age (P<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 anterior shoulder instability in a high demand population in either the BC or LD position. In multivariable analysis, younger age, but not surgical position, was an independent risk factor for recurrence.