Risk factors of instability following reverse total shoulder arthroplasty in patients with no history of shoulder surgery.

Introduction: As its indications expand, reverse total shoulder arthroplasty (rTSA) utilization continues to increase. Though relatively uncommon, instability following rTSA can be associated with significant morbidity and need for subsequent revision and treatment. This case control study aims to characterize factors leading to instability after rTSA, especially in those with no previous shoulder surgery. Methods: 194 rTSAs performed within the study period with appropriate operative indications and follow-up were included. Risk factors used in analysis included age, gender, BMI, ASA class, Charlson comorbidity index (CCI), glenosphere, tray, and liner size. Data was analyzed using a hierarchical binary logistical regression to create a predictive model for instability. Results: Seven patients sustained a post-operative dislocation. Mean time to dislocation was 60.4 weeks. Five required open reduction with placement of either a larger humeral tray or polyethylene spacer. One required open reduction with osteophyte removal, and one was converted to a resection arthroplasty. Dislocators were more likely to have a larger BMI (p = 0.002), higher ASA classification (p = 0.09), and larger liner size (p = 0.01). Conclusion: This study demonstrates a large series of patients successfully treated with rTSA. Dislocations were an uncommon complication, but were clearly associated with higher patient BMI, ASA classification, and increased liner size.

Opioid requirements in primary versus revision reverse shoulder arthroplasty.

PURPOSE: The purpose of this study is to evaluate the inpatient pain medication use of patients who had a revision shoulder arthroplasty procedure performed and compare them to a cohort of patients who had a primary reverse total shoulder arthroplasty (rTSA) performed to determine whether revision shoulder arthroplasty requires more pain medication.. METHODS: A retrospective review was performed on patients undergoing revision arthroplasty (n = 75) and primary rTSA (n = 340). Inpatient medication records were reviewed to tabulate the visual analog pain (VAS) all narcotic medication use, and total morphine equivalent units (MEUs) were calculated for the duration of the inpatient stay. RESULTS: There was no significant difference between groups regarding age, sex, body mass index, Charlson Comorbidity Index, American Society of Anesthesiologists score, preoperative narcotic pain medication use, tobacco use, postoperative VAS scores or hospital length of stay. There were no predictors of total postoperative MEUs identified. Overall, patients in the revision arthroplasty group received significantly less total MEUs than those in the primary rTSA group, 134.96 MEUs vs. 69.79 MEUs, respectively (p < .0005). CONCLUSION: The perceived notion that revision shoulder arthroplasty is more painful may cause providers to be more inclined to increase narcotic use, or use more invasive pain control techniques. Based on these data, we found that revision shoulder arthroplasty did not require an increased opioid requirement, longer length of stay or increase VAS, suggesting that these patients can often be managed similarly to primary rTSA.