Acromial and scapular spine fractures following reverse total shoulder arthroplasty: treatment dilemma and radiographic prognosticators for enhanced clinical outcomes: a multicenter study

Background: The management of acromial and scapular spine fractures (ASFs) after reverse total shoulder arthroplasty (rTSA) remains challenging, often prompting surgeons to opt nonoperative treatment. The reported outcomes vary due to multiple influencing factors. This study aimed to analyze prognostic factors affecting outcomes of nonoperatively treated ASFs following rTSA. Methods: Among 2,837 cases, 78 patients (2.7%) with ASFs following rTSA from 8 regional hospitals were retrospectively reviewed, including 10 surgical and 68 nonoperatively managed cases. The study focused on the 68 nonoperatively managed patients (56 females, 12 males, median age 74 years). The median ASF onset post-rTSA was 5 months (interquartile range: 3-9.8), with a mean follow-up after the diagnosis of ASFs of 30 months (range, 24-56). Fractures were classified using the Levy classification. The patient-acceptable symptom state for the American Shoulder and Elbow Surgeons (ASES) score and visual analog scale (VAS) score after rTSA (76 and 1.5, respectively) were used to group patients and assess demographic, clinical, and radiological prognostic factors, including fracture location, angulation, displacement, and union status. Results: In predicting below-acceptable VAS score (VAS score > 1.5), the absence of prior surgery had an odds ratio of 0.19 (95% confidence interval [CI], 0.04-0.79; P value: .023), while fracture angulation had an odds ratio of 1.11 (95% CI, 1.03-1.21; P value: .008). A fracture angulation ≥ 36° (specificity 90%, sensitivity 62.5%) and displacement ≥ 9 mm (specificity 90%, sensitivity 33.3%) were significant predictors of below-acceptable VAS score. For predicting below-acceptable ASES score (ASES score < 76), fracture angulation had an odds ratio of 1.13 (95% CI, 1.04-1.22; P value: .004). A fracture angulation ≥ 37° (specificity 90%, sensitivity of 62.8%) and displacement ≥ 10 mm (specificity 90%, sensitivity 34.9%) were significant predictors of a below-acceptable ASES score. Fracture location and nonunion status did not significantly impact outcomes. Conclusion: Fracture angulation was the most critical prognostic factor, negatively influencing nonoperatively managed ASF outcomes. Fracture location, nonunion status, and lateralization of rTSA did not affect clinical results. These findings will aid in patient counseling and guide decisions between nonoperative and surgical management.