Identifying rTSA Patients Most at Risk for Acromial and Scapular Fracture

Which patients are most at risk for acromial and scapular stress fractures after reverse shoulder arthroplasty (rTSA)?

Acromial and scapular fractures are rare but challenging complications after reverse shoulder arthroplasty, and can derail an otherwise successful outcome. Because these fractures have many causes, identifying which patients are truly at risk is difficult, especially considering almost every patient has at least one risk factor. Roche and colleagues sought to create a practical risk hierarchy by analyzing data from a massive cohort of 9,079 rTSA patients. By isolating how individual risks, such as age, sex and diagnosis, accumulate and interact, they aimed to move beyond simple statistics and provide surgeons with a formula for identifying the most vulnerable patients before they ever enter the operating room.

• Overall low incidence: The fracture rate was 1.52% for this medialized glenoid-lateralized humerus onlay reverse shoulder design.
• The power of combining risk factors: While individual factors like “female” or “>70years” were weak predictors, combinations were highly accurate at identifying fracture risk.
• The highest risk group: Female patients with rheumatoid arthritis (RA) over 80 years were 10.1 times more likely to experience a fracture than other patients.
• Fractures occur early: Over 73% of these fractures occurred within the first year, with 33% happening in the first 90 days.
• Impact on outcomes: Patients experiencing fractures had significantly worse range of motion and clinical scores than those who did not, even after healing. Additionally, scapular notching increased in patients after Levy type 3 fractures.

While the majority of patients have at least one risk factor, the risk increases dramatically when multiple factors accumulate. Identifying these high-risk accumulators preoperatively allows surgeons to optimize implant positioning/size selection to avoid over-tensioning the deltoid and potentially slow down postoperative rehabilitation to prevent a stress reaction from becoming a fracture.

These findings are limited because acromial fractures are difficult to diagnose radiographically; the true incidence may be higher than reported.