This case-control study tested how consistently four experienced shoulder surgeons plan reverse shoulder arthroplasty baseplate position. Each surgeon virtually planned baseplate placement on the same 30 degenerative shoulder CT scans using 3D software. The question: which positioning parameters have consensus and which still do not?
When you plan an RSA, remember that not all baseplate parameters carry equal certainty. Guide pin placement (inferior and posterior to prevent scapular notching) is a validated golden rule, which is why four independent surgeons placed it within 4 mm essentially every time.
Lateralization is the unsettled variable. It is set by reaming depth and graft thickness, and there is no validated minimum threshold, so even expert surgeons diverge widely (39.4% agreement within 2 mm).
The clinical stakes are real: lateralization reduces scapular notching and may aid rotation, but excessive graft-based lateralization risks non-union, and eccentric reaming for version correction sacrifices bone stock in B2 glenoids.
Version and inclination remain a matter of surgeon preference with only vague recommendations. Treat 3D planning as a tool that standardizes interpretation of the deformity, not as a substitute for consensus rules that do not yet exist for lateralization.
This case-control study tested how consistently four experienced shoulder surgeons plan reverse shoulder arthroplasty baseplate position. Each surgeon virtually planned baseplate placement on the same 30 degenerative shoulder CT scans using 3D software. The question: which positioning parameters have consensus and which still do not?
When you plan an RSA, remember that not all baseplate parameters carry equal certainty. Guide pin placement (inferior and posterior to prevent scapular notching) is a validated golden rule, which is why four independent surgeons placed it within 4 mm essentially every time.
Lateralization is the unsettled variable. It is set by reaming depth and graft thickness, and there is no validated minimum threshold, so even expert surgeons diverge widely (39.4% agreement within 2 mm).
The clinical stakes are real: lateralization reduces scapular notching and may aid rotation, but excessive graft-based lateralization risks non-union, and eccentric reaming for version correction sacrifices bone stock in B2 glenoids.
Version and inclination remain a matter of surgeon preference with only vague recommendations. Treat 3D planning as a tool that standardizes interpretation of the deformity, not as a substitute for consensus rules that do not yet exist for lateralization.