This study asks whether lateralizing the glenosphere center of rotation increases baseplate micromotion in reverse shoulder arthroplasty. The authors used a polyurethane foam bone model plus finite element analysis to test 7 glenosphere/baseplate combinations. COR offsets ranged from 0 to 10 mm across RSP and Delta III designs.
When you choose a more lateralized glenosphere to reduce scapular notching, the worry is that the longer moment arm loads the baseplate and drives early loosening. This study says that in good-quality bone, that worry does not bear out. Offsets from 0 to 10 mm all kept micromotion under the 150-µm ingrowth threshold.
Commit that 150-µm number to memory. It is the line between a baseplate that osseointegrates and one that loosens, and it underlies cementless fixation across arthroplasty. The critical caveat: this was healthy synthetic foam, not osteoporotic or deficient glenoid bone. In poor bone stock or instability, the authors recommend choosing a glenosphere with less COR offset to limit interface motion.
Remember the trade-off: Grammont medialized designs cause notching (24.5–96%) but lower migration, while lateralized designs reduce notching at the theoretical cost of interface stress.
This study asks whether lateralizing the glenosphere center of rotation increases baseplate micromotion in reverse shoulder arthroplasty. The authors used a polyurethane foam bone model plus finite element analysis to test 7 glenosphere/baseplate combinations. COR offsets ranged from 0 to 10 mm across RSP and Delta III designs.
When you choose a more lateralized glenosphere to reduce scapular notching, the worry is that the longer moment arm loads the baseplate and drives early loosening. This study says that in good-quality bone, that worry does not bear out. Offsets from 0 to 10 mm all kept micromotion under the 150-µm ingrowth threshold.
Commit that 150-µm number to memory. It is the line between a baseplate that osseointegrates and one that loosens, and it underlies cementless fixation across arthroplasty. The critical caveat: this was healthy synthetic foam, not osteoporotic or deficient glenoid bone. In poor bone stock or instability, the authors recommend choosing a glenosphere with less COR offset to limit interface motion.
Remember the trade-off: Grammont medialized designs cause notching (24.5–96%) but lower migration, while lateralized designs reduce notching at the theoretical cost of interface stress.