Osteophyte Model Generation for OA Analysis

Osteophyte models for each OA bone were generated by Boolean subtraction of the reference bone model from the OA bone model (Geomagic Wrap® 2017, 3D Systems, SC, USA); (Figure 2, Step 4). For the trapezium, the osteophyte model was limited to the distal periarticular region using an automated trimming workflow, which truncated the trapezium using a sectioning plane parallel to the radial-ulnar and volar-dorsal axis of the ACS that passed through the trapezial centroid (Figure 2, Step 5). Similarly, the first metacarpal osteophyte model was trimmed with a sectioning plane parallel to the radial-ulnar and volar-dorsal axis of the first metacarpal ACS; offset from the first metacarpal ACS origin the same magnitude as the trapezium ACS origin to trapezium centroid. Since both bones have more than one articular surface, and thus the potential for multiple regions of osteophyte formation, the trimming was performed to focus the analysis on only the trapezial-first metacarpal joint. Sensitivity analysis of ACS generation has been previously reported as repeatable and robust.^{34 (link)}