Scapular spine and acromion stress fractures following reverse shoulder arthroplasty have a high rate of failure following operative treatment.

INTRODUCTION: The purpose of this case series is to investigate outcomes for repair of fractures of the scapular spine and acromial process following reverse total shoulder arthroplasty (RTSA). METHODS: All adult patients who were treated operatively for a stress scapular spine or acromial fracture following a RTSA at a single center between 2013 and 2024 were identified. All patients underwent operative repair with plate and screw fixation with or without adjunctive bone grafting. Data collected included patient demographics, injury characteristics, fracture classification, surgical details, radiographic findings, and clinical outcomes, which were based on chart review of follow-up visits and revision surgeries. RESULTS: Among 2006 RTSA procedures performed during the study period, 18 patients (0.9%) developed a scapular spine or acromial stress fracture, 16 (88.9%) of which required operative fixation. Mean follow-up after fixation was 23 months. The cohort included 11 women (68.8%) and 5 men (31.2%), with a mean age of 71.9 years. All fractures were attributed to an insufficiency mechanism. Bone graft or biologic augmentation was performed in 11 patients (68.8%). Following index fracture fixation, 10 patients (62.5%) developed a postoperative complication or adverse clinical outcome, including nonunion in 6 patients (37.5%), fracture-related infection in 2 patient (12.5%), subsequent secondary acromial stress fracture in 1 patient (6.2%), and glenoid component loosening with humeral component dislocation in 1 patient (6.2%). Nine patients (56.3%) underwent at least one additional surgical procedure, including 8 patients (50.0%) who required an unplanned reoperation; hardware removal was the most common subsequent procedure (7/16, 43.8%). At final follow-up, 5 patients (31.3%) reported chronic pain, 3 patients (18.8%) had persistent nonunion, and 3 patients (18.8%) had hardware failure managed nonoperatively. The number of plates used and implant positioning did not differ significantly between patients who achieved union and those who did not (p = 0.264). CONCLUSION: Scapular spine and acromial stress fractures following RTSA are uncommon but clinically consequential complications of reverse total shoulder arthroplasty. Standard operative fixation demonstrated a low rate of success after a single intervention, underscoring the need for alternative treatment strategies. LEVEL OF EVIDENCE: Level IV.