Risk factors associated with intraoperative complications in primary shoulder arthroplasty

Background and purpose - Increasing numbers of shoulder arthroplasty are performed internationally. The predictors of intraoperative complications when implanting primary shoulder replacements are unknown. We determined the incidence of intraoperative complications during primary shoulder arthroplasty using the National Joint Registry of England, Wales, Northern Ireland and the Isle of Man (NJR), and analyzed the associated risk factors for complications. Patients and methods - NJR data on primary shoulder arthroplasty were scrutinized for intraoperative complications. 2 analyses were performed: the first examined the incidence and predictors of any recorded complication; the second examined the incidence and predictors for intraoperative fractures specifically. Analysis of risk factors was performed using multivariable binary logistic regression modeling. Results - 12,559 primary shoulder arthroplasties were recorded, with an intraoperative complication rate of 2.5%, the majority being fractures (1.6% overall). The incidence of all complications was lower in men (RR vs. women =0.63 (95% CI 0.47-0.84)). Patients undergoing surgery for avascular necrosis (RR =2.3 (1.3-4.2)) or trauma sequelae (RR =1.6 (1.2-2.7)) had a higher risk of complications compared with OA. Patients undergoing a stemmed hemiarthroplasty (RR =1.8 (1.2-2.5)) and reverse shoulder arthroplasty (RR 1.6 (1.1-2.5)) had a higher risk of complications compared with total shoulder arthroplasty. The incidence of all complications was less in patients undergoing resurfacing arthroplasty (vs. total shoulder arthroplasty (RR 0.42 (0.24-0.73)) and when performing the superior approach (vs. deltopectoral (RR 0.56 (0.39-0.80)). Interpretation - This is the first study to use a national data set to examine risk factors for intraoperative complications during all types of primary shoulder arthroplasty, and identifies several previously unrecognized risk factors, such as surgical approach.