Several patient factors may increase scapular fracture odds after RSA
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History of osteoporosis and hypothyroidism, as well as drop in BMI, increased the odds of scapular fracture after reverse shoulder arthroplasty, according to results presented at the American Shoulder and Elbow Surgeons Annual Meeting.
Vahid Entezari, MD, and colleagues reviewed electronic medical records of 739 patients who underwent primary RSA from 2006 to 2019 to extract demographic data, height, weight and BMI, list of comorbidities, American Society of Anesthesiologists classification, Charlson Comorbidity Index and details of fracture presentation and treatment.
“Recent X-ray and pre- and postoperative advanced imaging for all patients were evaluated by three trained reviewers,” Entezari said in his presentation.
Researchers classified scapular fractures using the Levy classification, with type 1 selected when the fracture was anterior to the acromioclavicular joint, type 2 when the fracture was posterior to the acromioclavicular joint but not in the spine of the scapula and type 3 when the fracture was within the scapular spine region.
Entezari noted 38 patients had 51 symptomatic fractures and 51% of patients had a type 2 fracture.
“One-third of fractures were initially missed by the treating physician, and the majority of these missed fractures were in patients with no history of injury leading to delay of 9.3 months of diagnosis,” Entezari said.
Female patients had a statistically significantly higher rate of fracture at 9% vs. 3.5% for male patients, according to Entezari. He added multivariate logistic regression analysis showed history of osteoporosis and hypothyroidism independently predicted scapular fracture, while a one unit drop in BMI increased the odds of scapular fracture after RSA. Entezari noted displacement in 88% of fractures; however, most of the fractures were treated nonoperatively.
“On the final follow-up, 59% of fractures were healed on X-ray and 70% were pain free,” Entezari said. “Eight patients underwent surgical fixation, one with tension band and seven with plate osteosynthesis. Out of those patients, 62.5% went on to nonunion, with four developing hardware failure.”
Perspective
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Thomas W. (Quin) Throckmorton, MD, FAAOS
Scapular fractures continue to be a dreaded complication after reverse total shoulder arthroplasty. This work by Vahid Entezari, MD, and colleagues suggests these fractures, seen in approximately 7% of RTSAs in their series, may be more common than initially thought and are often diagnosed late. This highlights the need for a high index of suspicion to identify these fractures in the postoperative period. Risk factors for this complication include female sex, osteoporosis and diminishing BMI; all indicators of poor bone quality. Unfortunately, these fractures heal poorly, with a 59% radiographic healing rate overall and a nonunion rate of 62% after fixation. This indicates postoperative scapular fractures are a complication that is best avoided rather than treated. Further refinement of fracture specific implants and surgical techniques to manage this complication will hopefully improve future outcomes.
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Entezari V, et al. Predictors of scapular fracture following reverse total shoulder arthroplasty: Analysis of 739 consecutive cohort. Presented at: American Shoulder and Elbow Surgeons Annual Meeting; Oct. 2-3, 2020 (virtual meeting).
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