Effect of Glenoid Version and Width on Outcomes of Arthroscopic Posterior Shoulder Stabilization

Abstract

Background: Despite an increased awareness of the condition, the diagnosis, classification, and treatment of recurrent posterior shoulder instability remain challenging. No clear relationship has been established between glenohumeral morphologic characteristics and the risk for posterior shoulder instability or with outcomes after treatment. Purpose: To examine the structure of the glenoid in a large series of athletic patients with symptomatic unidirectional posterior instability and to correlate these findings with the objective and subjective clinical outcome of arthroscopic posterior capsulolabral repair. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 118 magnetic resonance arthrograms of athletes with unidirectional recurrent posterior shoulder instability treated with an arthroscopic posterior capsulolabral repair were reviewed, and measurements of glenoid labral, chondral, and bone version and labral and bone width were performed. The patients were evaluated preoperatively and postoperatively with the American Shoulder and Elbow Surgeons (ASES) scoring system and with standardized subjective pain and stability scales. Results: The mean glenoid labral, chondral, and bone versions were 10.8°, 10.1°, and 9.5°, respectively. The mean labral width was 30.9 mm and the mean bone width 28.9 mm. Patients with wider and more retroverted glenoid bone had better mean preoperative pain and ASES scores than did those with narrow and more anteverted glenoid bone. At final postoperative follow-up, patients with wider glenoids continued to have better pain and ASES scores and decreased risk of failure. In contrast, no significant differences in outcome scores were detected among subjects with regard to glenoid bone version. There was no correlation between chondral and labral width or version with any outcome measure preoperatively or postoperatively. Thirteen patients had unsuccessful initial capsulolabral repairs (ASES scores <60 and stability scores ≥6), demonstrating a 3.0-mm smaller overall labral width and 3° less labral retroversion but no bony version differences when compared with the successful cohort. Conclusion: Although higher glenoid retroversion was noted in this patient population as compared with previous studies in normal populations, there were no significant differences in outcomes after treatment among subjects with regard to glenoid version. However, increased glenoid width did predict better outcomes after posterior capsulolabral repair.