Browsing by Author "Fung, Anita"

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    Effects of footwear and stride length on metatarsal strains and failure in running
    (2017-11) Firminger, Colin R.; Fung, Anita; Loundagin, Lindsay L.; Edwards, William Brent
    The metatarsal bones of the foot are particularly susceptible to stress fracture owing to the high strains they experience during the stance phase of running. Shoe cushioning and stride length reduction represent two potential interventions to decrease metatarsal strain and thus stress fracture risk.
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    Experimental validation of finite element predicted bone strain in the human metatarsal
    (2017-01) Fung, Anita; Loundagin, Lindsay L.; Edwards, William Brent
    Metatarsal stress fracture is a common injury observed in athletes and military personnel. Mechanical fatigue is believed to play an important role in the etiology of stress fracture, which is highly dependent on the resulting bone strain from the applied load. The purpose of this study was to validate a subject-specific finite element (FE) modeling routine for bone strain prediction in the human metatarsal. Strain gauge measurements were performed on 33 metatarsals from seven human cadaveric feet subject to cantilever bending, and subject-specific FE models were generated from computed tomography images. Material properties for the FE models were assigned using a published density-modulus relationship as well as density-modulus relationships developed from optimization techniques. The optimized relationships were developed with a 'training set' of metatarsals (n=17) and cross-validated with a 'test set' (n=16). The published and optimized density elasticity equations provided FE-predicted strains that were highly correlated with experimental measurements for both the training (r2≥0.95) and test (r2≥0.94) sets; however, the optimized equations reduced the maximum error by 10% to 20% relative to the published equation, and resulted in an X=Y type of relationship between experimental measurements and FE predictions. Using a separate optimized density-modulus equation for trabecular and cortical bone did not improve strain predictions when compared to a single equation that spanned the entire bone density range. We believe that the FE models with optimized material property assignment have a level of accuracy necessary to investigate potential interventions to minimize metatarsal strain in an effort to prevent the occurrence of stress fracture.
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    Experimental Validation of Finite Element Predicted Bone Strain in the Human Metatarsal
    (2017) Fung, Anita; Edwards, William Brent; Boyd, Steven Kyle; Schmidt, Tannin; Li, Leping; Wiley, James Preston
    The objective of this study was to verify and validate a finite element modeling routine for the human metatarsal, which is a common location for stress fractures. Experimental strain measurements on 33 human cadaveric metatarsals subject to cantilever bending were compared with strain predictions from finite element (FE) models generated from computed tomography images. For the material property assignment of the FE models, a published density-elasticity relationship was compared with density-elasticity equations developed using optimization techniques. The correlations between the measured and predicted and predicted strains were very high (r2≥0.94) for all of the density-elasticity equations. However, the utilization of an optimized density-elasticity equation improved the accuracy of the finite element models, reducing the maximum error between measured and predicted strains by 10% to 20%. The finite element modeling routine could be used for investigating potential interventions to minimize metatarsal strains and the occurrence of metatarsal stress fractures.