Total shoulder arthroplasty (TSA) is the current standard treatment for severe osteoarthritis of the glenohumeral joint [1]. Often, severe arthritis is associated with abnormal glenoid version or excessive posterior wear [2]. Reaming to correct more than 15° of retroversion back to neutral is not ideal as it may remove an excessive amount of the outer cortical support and medialize the glenoid component [3]. Two recent glenoid components with posterior augments—wedged and stepped—have been designed to address excessive posterior wear and to allow glenoid component neutralization. Hypothetically, these augmented glenoid designs lessen the complications associated with using a standard glenoid component in cases of shoulder osteoarthritis with excessive posterior wear. We set out to determine which implant type (standard, stepped, or wedged) corrects retroversion while removing the least amount of bone in glenoids with posterior erosion. Serial shoulder CT scans were obtained from 121 patients before total shoulder arthroplasty. These were then classified using the Walch Classification. We produced 3D models of the scapula from CT scans for 10 subjects that were classified as B2 using the software MIMICS (Materialise, Belgium). Each of these 10 glenoid subjects were then virtually implanted with standard, stepped, and wedged glenoid components (Fig 1). The volume of surgical bone removed and maximum reaming depth were calculated for each design and for each subject. In addition, the area of the backside of the glenoid in contact with cancellous versus cortical bone was calculated for each glenoid design and for each subject (Fig 2). ANOVA testing was performed.Introduction:
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