Arnone JC, Crist BD, Ward CV, et al. - The present study was conducted to describe a new technique of evaluating variability in human femoral geometry and to use this data to optimize intramedullary nail geometry for a better fit within the femoral canal. Researchers classified computed tomography (CT) scans of forty intact adult human femora according to race, gender, and age, and were reconstructed digitally into three-dimensional solid models. Using ANOVA, geometric features were then assessed and compared among groups. In femoral geometry, considering variation among patients when designing implantable fixation devices may be important. The data indicate that femoral size varies between adults by gender, with males being larger than females. Although there may be slight differences between European and African Americans, the pattern of curvature, however, did not differ. As such, for the entire population, the proposed average femoral curvature function estimated here may be sufficient. It was shown that insertion-induced stresses in the femur were within the allowable range for the geometrically-optimized nail and seem more desirable than in other common nail designs.