This finite element analysis models glenoid-sided lateralization in reverse shoulder arthroplasty. It compares the mechanical cost of bony lateralization (BIO-RSA graft) versus prosthetic offset through the glenosphere or baseplate. It also tests how glenosphere size, baseplate tilt, and screw orientation affect baseplate stress and displacement.
When you need to lateralize the glenoid in RSA to reduce scapular notching or restore the joint line, this study tells you the method matters as much as the amount. Bony lateralization sacrifices central post purchase in native bone, so displacement crosses the 150 micron osseous-integration threshold at just 5 mm. Prosthetic offset preserves screw purchase and stays safe out to 10 mm.
The practical rule: keep bone graft to 5 mm or less, but you can use up to 10 mm of prosthetic lateralization. A hybrid construct (5 mm graft plus 4 mm lateralized glenosphere) is a proposed alternative but was not tested here. Optimize fixation further with a smaller glenosphere, 10 degree inferior tilt, and divergent peripheral screws.
Remember the caveat: real grafts compact on impaction and clinical healing rates run 98-100%, so this worst-case model overstates the risk. It sharpens judgment rather than dictating practice.
This finite element analysis models glenoid-sided lateralization in reverse shoulder arthroplasty. It compares the mechanical cost of bony lateralization (BIO-RSA graft) versus prosthetic offset through the glenosphere or baseplate. It also tests how glenosphere size, baseplate tilt, and screw orientation affect baseplate stress and displacement.
When you need to lateralize the glenoid in RSA to reduce scapular notching or restore the joint line, this study tells you the method matters as much as the amount. Bony lateralization sacrifices central post purchase in native bone, so displacement crosses the 150 micron osseous-integration threshold at just 5 mm. Prosthetic offset preserves screw purchase and stays safe out to 10 mm.
The practical rule: keep bone graft to 5 mm or less, but you can use up to 10 mm of prosthetic lateralization. A hybrid construct (5 mm graft plus 4 mm lateralized glenosphere) is a proposed alternative but was not tested here. Optimize fixation further with a smaller glenosphere, 10 degree inferior tilt, and divergent peripheral screws.
Remember the caveat: real grafts compact on impaction and clinical healing rates run 98-100%, so this worst-case model overstates the risk. It sharpens judgment rather than dictating practice.