Patient risk factors for acromial stress fractures after reverse shoulder arthroplasty: a multicenter study.

BACKGROUND

Despite the growing recognition of acromial stress fractures (ASFs) after reverse total shoulder arthroplasty (RTSA), most of the current data are derived from single-center studies with limited generalizability. This multicenter study investigated the incidence of ASFs after RTSA and identified preoperative patient characteristics associated with their occurrence.

METHODS

Using 2 institutional registries from different regions of the United States, we identified 1479 patients undergoing either primary or revision RTSA between 2013 and 2018 with minimum 3-month follow-up. ASFs were defined as radiographic evidence of an acromial or scapular spine fracture with clinical symptoms (eg, tenderness over the acromion or scapular spine). Multivariable logistic regression was performed to identify preoperative patient factors associated with the development of ASFs.

RESULTS

Overall, 54 (3.7%) patients were diagnosed with an ASF after RTSA. Patient-related factors independently associated with the development of an ASF included female sex (odds ratio [OR], 2.21 reference: male; 95% confidence interval [CI], 1.03-4.74; P < .05), rheumatoid arthritis (OR, 2.30; 95% CI, 1.02-5.16; P < .05), osteoporosis (OR, 2.55; 95% CI, 1.24-5.21; P < .05), a diagnosis of degenerative joint disease with rotator cuff tear (OR, 4.74 reference: degenerative joint disease without rotator cuff tear; 95% CI, 1.84-12.23; P < .05), and fracture malunion/nonunion (OR, 5.21; 95% CI, 1.20-22.76; P < .05).

CONCLUSIONS

The non-negligible percentage of ASFs that occur after RTSA is associated with the diagnoses of rotator cuff dysfunction and chronic fracture sequelae in female patients with suboptimal bone health. This information can be used to counsel patients and set expectations about potential setbacks in recovery.