Development and validation of a series of three-dimensional finite element models of the equine metacarpus

Three-dimensional finite element (FE) models of the left metacarpi of five adult horses were developed from quantitative computed tomography data, using the algorithms of Keyak er al. (1990, J Biomed. Engng 12, 389-397). The metacarpi were then equipped with 12 rosette strain gauges and loaded non-destructively in a mechanical testing machine. The bones and the models were loaded in axial compression, with the load evenly distributed across the distal row of carpal bones, and with a point load placed mediad to the sagittal midline, to a load equivalent to three times body weight (-15 kN); and in sagittal four-point bending to -2 kN. Maximum and minimum principal strains from the models were compared with those at the strain gauge rosettes. There were significant (p<0.001) and strong (0.69<r<0.90) correlations between predicted and observed surface principal strains, most often resolving as second- or third-order polynomial relationships. In most cases, particularly at extreme strain magnitudes, the models tended to overestimate the observed strain magnitudes. These data suggest that the models are robust and accurate predictors of surface strains. Validation of these models lends further support for the use of this method of automated three-dimensional FE modeling, with its emphasis on accurate, individualized portrayal of structural geometry and material distribution, in research applications, and specifically for the use of these models in the study of the biology and mechanics of the equine metacarpus. (C) 1997 Elsevier Science Ltd.