Predictive factors of intraoperative conversion to reverse total shoulder arthroplasty in patients with primary glenohumeral arthritis.

Background: Many factors play a role in decision making for arthroplasty type in patients with glenohumeral osteoarthritis (GHOA). The purpose of this study was to evaluate preoperative and intraoperative factors that might predict the need for reverse total shoulder arthroplasty (rTSA) vs. anatomic total shoulder arthroplasty (aTSA) for patients with primary GHOA. Secondarily, American Shoulder and Elbow Surgeons (ASES) were compared. Methods: Patients with primary GHOA indicated for aTSA vs. rTSA were identified. Preoperative records were reviewed for demographics, range of motion, rotator cuff strength, and glenoid morphology. Operative reports were assessed to identify intraoperatively rotator cuff pathology and glenoid deficiency. ASES scores at 2 years postoperative were collected. Results: One hundred eleven patients were included from 2018 to 2021. Ninety-four patients underwent aTSA, while 17 were intraoperatively converted to rTSA. There were no significant differences in age, body mass index, or preoperative Walch classification between cohorts. rTSA patients had significantly decreased preoperative external rotation ( Conclusion: Many patients with primary GHOA are well-served with aTSA. However, there are patients with primary GHOA in which rTSA may be ideal given rotator cuff deficiency or glenoid defects felt to limit aTSA glenoid component placement. This study highlights the need for preoperative external rotation and intraoperative evaluation of rotator cuff integrity and glenoid bone stock.