Glenoid morphology after reaming in computer-simulated total shoulder arthroplasty

Area of Science:

• Orthopedic Surgery
• Biomechanical Engineering
• Medical Imaging

Background:

• The relationship between glenoid reaming parameters and bone loss in total shoulder arthroplasty (TSA) is not well-defined.
• Existing research lacks clarity on how reaming depth, placement, and version correction impact glenoid implant surface area and bone preservation.

Purpose of the Study:

• To investigate the effects of reaming depth, reamer placement, and version correction on glenoid implant surface area and bone volume removed during TSA.
• To test the hypotheses that large reaming depths are insufficient for full implant contact with large version corrections, bone loss is linear with reaming depth, and initial reamer placement is inconsequential.

Main Methods:

• Computer-simulated reaming was performed on 10 patient-specific models derived from CT scans of patients with osteoarthritis.
• Key variables analyzed included reaming depth, reamer placement (anterior, posterior, superior, inferior deviations), and version correction.
• Calculations focused on the resulting reamed glenoid surface area for implantation and the total bone volume removed.

Main Results:

• Increased reaming depth and decreased version correction significantly enhanced reamed surface area (P < .0001).
• A strong quadratic relationship (r² = 0.999) was observed between bone volume removed and reaming depth.
• Posteriorly deviated reamer placement resulted in significantly greater bone volume removal compared to anterior, superior, or inferior deviations (P < .05).

Conclusions:

• Smaller version corrections in TSA optimize implant-bone surface contact.
• Increasing reaming depth yields diminishing returns in conforming surface area while causing substantial glenoid bone stock loss.
• Posteriorly directed off-center reamer placement poses the highest risk for excessive bone removal.