This retrospective multicenter cohort asks whether glenoid-sided lateralization up to 8 mm raises the risk of acromial or scapular spine stress fracture after reverse shoulder arthroplasty. All cases used a 135° inlay humeral component. The goal was to separate lateralization from distalization as competing fracture risk factors.
When you plan an RSA and want more impingement-free rotation, glenoid-sided lateralization up to 8 mm with a 135° inlay stem is safe from a fracture standpoint.
The fracture risk lives in the vertical dimension, not the horizontal one. Overlengthening the deltoid through aggressive distalization stresses the acromion, and this study quantifies it: 121% higher risk per cm of delta AHD, 19% per mm of glenosphere overhang.
The practical mental model: watch the change in acromiohumeral distance, not just the final position. A patient with pronounced preoperative superior humeral migration who gets a large correction is at higher risk than the endpoint alone suggests.
Remember this is Level III, industry-funded, single-implant-system data with 1-year follow-up and no bone mineral density, so treat lateralization safety as well-supported but the secondary distalization findings as directional. Dominant-arm surgery doubling risk is a useful counseling point when the arthritic shoulder is the dominant side.
This retrospective multicenter cohort asks whether glenoid-sided lateralization up to 8 mm raises the risk of acromial or scapular spine stress fracture after reverse shoulder arthroplasty. All cases used a 135° inlay humeral component. The goal was to separate lateralization from distalization as competing fracture risk factors.
When you plan an RSA and want more impingement-free rotation, glenoid-sided lateralization up to 8 mm with a 135° inlay stem is safe from a fracture standpoint.
The fracture risk lives in the vertical dimension, not the horizontal one. Overlengthening the deltoid through aggressive distalization stresses the acromion, and this study quantifies it: 121% higher risk per cm of delta AHD, 19% per mm of glenosphere overhang.
The practical mental model: watch the change in acromiohumeral distance, not just the final position. A patient with pronounced preoperative superior humeral migration who gets a large correction is at higher risk than the endpoint alone suggests.
Remember this is Level III, industry-funded, single-implant-system data with 1-year follow-up and no bone mineral density, so treat lateralization safety as well-supported but the secondary distalization findings as directional. Dominant-arm surgery doubling risk is a useful counseling point when the arthritic shoulder is the dominant side.