80 human tibia bones from healthy adults (38 male, aged from 20 to 70 years; 42 female, aged from 23 to 68 years) were scanned using spiral CT, and three-dimensional images were reconstructed using the surface shaded display (SSD) method. GE Hispeed ZX/i scanning was performed using the configuration shown in Table 1 .
Three-dimensional reconstruction of tibia geometry was performed using a GE ADW4.0 Image workstation. Three anatomical indices (i.e., the length of twisting segment on the lateral surface of the tibia, twisting angles on different twisting segments, and the anteversion angle of the lateral surface of the tibia) were measured in the three-dimensional images by the GE ADW4.0 Image workstation. Because there was a different torsion angle on the outer surface of the tibia, in order to understand the torsion angle changes, we divided the twist section into four equal parts, that is, first twisting section, second twisting section, third twisting section, and fourth twisting section. The measured indices were then statistically analyzed using SPSS 12.0 statistical analysis software with T-test, ANOVA test and correlation analysis test. There was no history of trauma, surgery, or skeletal disorders in any of the individuals involved in this study.
Three-dimensional reconstruction of tibia geometry was performed using a GE ADW4.0 Image workstation. Three anatomical indices (i.e., the length of twisting segment on the lateral surface of the tibia, twisting angles on different twisting segments, and the anteversion angle of the lateral surface of the tibia) were measured in the three-dimensional images by the GE ADW4.0 Image workstation. Because there was a different torsion angle on the outer surface of the tibia, in order to understand the torsion angle changes, we divided the twist section into four equal parts, that is, first twisting section, second twisting section, third twisting section, and fourth twisting section. The measured indices were then statistically analyzed using SPSS 12.0 statistical analysis software with T-test, ANOVA test and correlation analysis test. There was no history of trauma, surgery, or skeletal disorders in any of the individuals involved in this study.