Acromion Morphology Is Associated With Failure of Arthroscopic Posterior Capsulolabral Repair

Posterior shoulder instability has recently been linked to a higher and flatter acromion. However, the effect of acromial morphology on surgical outcomes has not been evaluated.

To evaluate differences in acromial morphology between patients undergoing primary and revision arthroscopic stabilization for posterior shoulder instability.

Case-control study; Level of evidence, 3.

A series of patients who underwent either primary or revision arthroscopic stabilization for posterior shoulder instability between 2001 and 2022 were identified. Revision patients were matched to nonrevision patients based on age, sex, and sport. Comparisons of patient characteristics and acromial and glenoid morphology were done between groups using previously described magnetic resonance imaging parameters, including posterior acromial tilt (PAT), anterior acromial coverage (AAC), posterior acromial coverage (PAC), and posterior acromial height (PAH). Glenoid bone loss and glenoid version were also evaluated. Continuous variables were compared between groups using a 2-tailed Student t test.

A total of 37 patients who underwent revision posterior shoulder stabilization during the study period were identified and matched to 37 patients who underwent primary posterior shoulder stabilization. The mean ages of the primary and revision patients at the time of initial surgery were 21.5 ± 4.8 years (range, 13-35 years) and 19.6 ± 6.1 years (range, 12-45 years), respectively (P = .95). Men comprised 54% of each group. The mean PAT in the primary and revision groups was 51.6° and 53.7° (P = .32), while the mean PAH was 10 mm and 13.5 mm (P = .04), respectively. The mean AAC in the primary and revision groups was 4.44° and 7.10° (P = .20), while the mean PAC was 72.1° and 63.3°± 8.11° (P = .08), respectively. No difference was found in the glenoid version (6.22° in the primary group vs 8.08° in the revision group; P = .06). The mean glenoid bone loss was 0.57% (range, 0%-8.9%) in the primary group and 1.4% (range, 0%-5.8%) in the revision group (P = .02).

A higher acromion was associated with requiring revision of previous arthroscopic posterior capsulolabral repair. PAT and coverage were not significantly different between patients undergoing primary versus revision repair. There was no significant difference in glenoid version between groups. Although the amount was small, glenoid bone loss was statistically higher in the revision group.