Comparison of two different finite element modeling pipelines for virtual mechanical testing of the distal third metacarpal bone in Thoroughbred racehorses

Condylar stress fracture of the third metacarpal bone (MC3) in Thoroughbred racehorses is a common catastrophic injury and identification of horses at heightened risk remains subjective. Standing computed tomography (sCT) is a practical screening tool that is sensitive to fatigue-induced structural changes. Data from sCT also allows for patient-specific finite element analysis (FEA) of the distal MC3 and prediction of subchondral bone strain, as a potential objective classifier of racehorses at heightened risk. The goal of this study was to compare two independently developed sCT-based subject-specific FEA pipelines for virtual mechanical testing of the distal MC3. One pipeline models the full 3D distal MC3 (UWMSN), while the other uses a simpler approach by using single sCT slices (UMELB). Four (n=4) MC3 condyles from four Thoroughbred racehorses were selected for the study. Models were generated using both pipelines and the predicted subchondral bone strain was compared. UMELB predicted smaller subchondral strain compared to UWMSN, likely due to more limited modes of deformation. Although the UWMSN pipeline can identify elevated subchondral strain in horses with high fatigue damage, it is more labor intensive and computationally expensive. With further tuning and validation, the UMELB pipeline could be used as a simpler and faster approach for prediction of subchondral strain in the distal MC3.