Beach Chair and Lateral Decubitus Positions for Anterior Shoulder Stabilization Surgery

Abstract

The purpose of the present study was to assess patient and baseline operative repair variables utilized in the primary arthroscopic repair for anterior shoulder instability surgeries performed in the beach chair [BC] and lateral decubitus [LD] positions. It was hypothesized (1) that there would be more frequent anchor placement inferiorly on the glenoid when surgery was performed in the LD position and that (2) labrum tear characteristics would be similar between LD and BC positioning groups. The present study is a cross-sectional analysis of a large, multicenter prospective cohort study, the Multicenter Orthopaedic Outcomes Network (MOON) Shoulder Group. Participants ≥12 years of age that underwent primary arthroscopic anterior shoulder stabilization surgery were queried from November 2012 through May 2019 for inclusion. Participants with workers’ compensation were not eligible for enrollment; participants with concomitant rotator cuff repair, isolated superior labrum anterior-posterior (SLAP) tears, or concomitant open and arthroscopic procedures were excluded. Patients were prospectively enrolled and demographic characteristics were collected at baseline for the BC and LD groups. The following baseline repair variables were collected for the BC and LD cohorts, respectively: labrum tear characteristics; anchor number and location of placement (Figure 1); and placement of an anchor at the lowest inferior position. Study data was managed using Research Electronic Data Capture (REDCap). Continuous variables were assessed utilizing mean ±standard deviation; median (min.-max.) was used for distributions that were not normal. Between group comparisons were conducted utilizing the Wilcoxon Rank Sum Test. Sub-stratification analyses were conducted (1) excluding patients with concomitant SLAP repairs and (2) excluding repairs extending into the posterior quadrant. All statistical analyses were performed using SAS software version 9.4 (SAS Institute, Inc., Cary, NC). The BC position (357, 58.1%) was more common vs. the LD position (257, 41.9%). The length of the labrum tears documented were greater for patients having surgery in the LD [median: 126.0º (range: 36-270º) vs. BC [median: 108.0º (range: 18-270º)], p<0.01]. The number of anchors used for labral tears in the inferior quadrant) differed significantly across patient groups, with ≥ 2 anchors placed inferiorly more often in the LD position [BC; 80 (22.4%) vs. LD; 140 (54.5%), p<0.01]. The LD position was associated with more frequent placement of an anchor at the 6 o’clock position on the glenoid [(LD 137, 53.3%) vs. BC position (74, 20.7%) p<0.01]. Sub-stratification analyses excluding participants with (1) concomitant SLAP repairs and (2) repairs extending into the posterior quadrant supported the number and location of anchors placed as well as anchor placement at the lowest inferior position (all p<0.01). The median length of the labral tear documented in the LD position was longer than that documented in the BC position. This could represent more extensive tear patterns or possibly improved visualization in LD positioning. Patients undergoing anterior instability arthroscopic surgery in the LD position more frequently had ≥ 2 anchors in the inferior quadrant and a 6 o’clock anchor placed.