Patient-specific FE analyses of metatarsal bones with inhomogeneous isotropic material properties.

The mechanical response of human metatarsal bones is of importance in both research and clinical practice, especially when associated with the correction of Hallux Valgus. Verified and validated patient-specific finite-element analysis (FEA) based on CT scans developed for human femurs are extended here to the first and second metatarsal bones. Two fresh-frozen metatarsal #1 and five metatarsal #2 bones from three donors were loaded in-vitro at three different angles. Holes typical to Hallux Valgus correction were then drilled in the bones, which were reloaded until fracture. In parallel, high-order FE models of the bones were created from CT-scans that mimic the experimental setting. We validated the FE results by comparison to experimental observations. Excellent agreement was obtained with R(2)=0.97 and slope of the regression line close to 1. We also compared the FE predicted fracture load and location for the second metatarsal bones with these measured in the experiment, demonstrating an excellent prediction within 10% difference. After validation of the FE predictions, they were used to investigate the effect of drilled hole position, dimension and the insertion of a metallic device on the mechanical response so to optimize the outcome of the Hallux Valgus correction. This study further substantiates the potential use of FEA in clinical practice.