What is the effect of postoperative scapular fracture on outcomes of reverse shoulder arthroplasty?

Background: Postoperative scapular fracture is a common complication after reverse shoulder arthroplasty (RSA). The purpose of this study was to determine its effect on RSA patient outcomes. Methods: A retrospective, case-control study of 25 nonoperatively treated postoperative scapular fractures after RSA were analyzed with a minimum 2-year follow-up from surgery and 1-year follow-up from fracture. Eligible patients were matched 1:4 to a control group for age, sex, follow-up time, surgery indication, and primary operation vs revision. Outcome measures, including American Shoulder and Elbow Surgeons (ASES) score and range of motion, were compared between fracture cases and controls. Also analyzed were radiographic features, including fracture location (acromion vs scapular spine) and healing. Results: Incidence of scapular fracture after RSA in this series was 3.1%. Fractures occurred from 1 to 94 months postoperatively. The revision rate was higher in the fracture group (8% vs 2%) but did not reach statistical significance (P = .18). Fracture patients had improved (δASES, 21) but inferior clinical outcomes, with a postoperative ASES score of 58.0 compared with 74.2 (P ≤ .001). Change in range of motion also diminished in the fracture group, with a mean gain of 26° forward elevation compared with 76° (P < .001). Fracture location (P = .54) or healing (P = .40) did not affect outcome. Conclusion: Postoperative scapular fractures may occur at any point postoperatively; increasing incidence is likely as longer follow-up becomes available. This complication leads to inferior clinical results compared with controls. However, patients show improvement compared with their preoperative measurements, even at longer-term follow-up. Patients with postoperative scapular fractures may have increased risk of revision.