Acromial spine fracture after reverse total shoulder arthroplasty: a systematic review.

BACKGROUND:
Reverse total shoulder arthroplasty (RSA) accounts for nearly one-third of shoulder arthroplasty utilization nationally. The complication rate has increased concurrently. Consensus is lacking regarding the incidence, etiology, and treatment of acromial or scapular spine fractures after RSA. The purpose of our study was to perform a systematic review of the literature to analyze the occurrence and outcomes of this complication.

METHODS:
The MEDLINE, Embase, Google Scholar, and Cochrane databases were queried in late 2017 for combinations of the words "acromial," "fracture," "reverse," "shoulder," and "arthroplasty." We included all studies that contained a clearly defined performance of RSA, acromial fracture(s) noted, and treatment (if any) and outcomes of treatment. The initial search yielded 50 studies; 32 met the inclusion criteria.

RESULTS:
Among 3838 RSAs, 159 acromial fractures were reported, for an overall incidence of 4.14%; the mean time to diagnosis from surgery was 9 months (range, 1.3-24 months). Treatments included nonoperative treatment in a sling or abduction brace in 139 cases and open reduction-internal fixation in 20. Regardless of treatment, patients reported inferior function after fracture compared with initially after RSA. Forward flexion was 95° (range, 30°-110°), abduction was 76° (range, 30°-180°), the Constant score was 63 (range, 59-67.5), and the American Shoulder and Elbow Surgeons score was 57 (range, 7-83); all values were reduced compared with patients without fractures.

CONCLUSION:
This study suggests the occurrence of acromial fractures after RSA is a common event, with a rate of over 4%. These fractures correlate with worse postoperative outcomes regardless of treatment method; open reduction-internal fixation was not shown to be clinically superior despite a limited complication rate. Additional high-quality studies addressing acromial spine fracture after RSA are needed.