These authors point out that acromial (ASF) and scapular spine (SSF) stress fractures are well-recognized complications of reverse shoulder arthroplasty (RSA).
They conducted a 15 center study to determine the incidence of ASF/SSF after RSA, and the preoperative patient characteristics associated with their occurrence.
They included patients undergoing either primary or revision RSA with a minimum three-month follow-up. Only symptomatic ASF/SSF diagnosed by radiograph or computed tomography were considered.
They identified 6,755 RSAs with an average follow-up of 19.8 months (range, 3-94). About 1 in 26 patients undergoing RSA developed a symptomatic ASF or SSF, usually within the first year of surgery. The total scapular fracture incidence rate was 3.9% (n=264), of which 3.0% (n=200) were ASF and 0.9% (n=64) were SSF.
Fractures occurred at an average 8.2 months (0-64) following RSA with 21.2% (n=56) following a trauma.
Patient-related factors independently predictive of ASF were: chronic dislocation (OR, 3.67), massive rotator cuff tear without arthritis (OR, 2.51), rotator cuff arthropathy (OR, 2.14), self-reported osteoporosis (OR, 2.21), inflammatory arthritis (OR, 2.18), female sex (OR, 1.51), and older age (OR, 1.02 per 1-year increase).
Factors independently associated with the development of SSF included: osteoporosis (OR, 2.63), female sex (OR, 2.34), rotator cuff arthropathy (OR, 2.12), and inflammatory arthritis (OR, 2.05).
The authors did not report on the relationship of prosthesis type or positioning on ASF or SSF.
Comment: This is an important study in that it points out the typical time of presentation of ASF and SSF and the risk factors for these complications that can be devastating for the patient.
Surgeons and patients may wish to consider alternative methods of management of rotator cuff arthropathy (see this link) and massive cuff tear (see this link) in high risk patients.
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