Glenohumeral arthrosis in anterior instability before and after surgical treatment: incidence and contributing factors.

BACKGROUND Few large series of arthropathy related to anterior glenohumeral instability are available in the orthopaedic literature, preventing analysis of the incidence and the risk factors of preoperative and postoperative glenohumeral arthritis. HYPOTHESIS Anterior stabilization surgery influences the risk factors of glenohumeral arthritis. STUDY DESIGN Retrospective review. METHODS There were 570 patients who underwent an instability procedure. Clinical and radiographic preoperative data were collected for these patients. Arthritis was evaluated preoperatively and postoperatively with the Samilson classification. The mean age at surgery was 31.9 years. Follow-up averaged 6.5 years. RESULTS The preoperative incidence of arthritis was 9.2%. Arthritic risk factors were older age at the initial dislocation and at surgery, increased length of time from the initial dislocation until surgery, and the presence of osseous glenoid rim lesions. Postoperative arthritis in patients without any preoperative arthritis occurred in 19.7% and was correlated with older age at the initial dislocation and at surgery, increased number of dislocations, and longer follow-up. Decreased external rotation at latest follow-up correlated with arthritis, although whether this was the cause or the effect was unclear. CONCLUSIONS Similar factors contribute to preoperative and postoperative arthritis in patients with anterior glenohumeral instability, suggesting that surgery does not influence the risk factors of arthritis. Although decreased external rotation with the arm at side statistically correlated with arthritis in this study, the authors were unable to establish this as an effectual relationship because nearly all patients with glenohumeral osteoarthritis, whether instability related or not, have decreased external rotation.