Gender Variation in the Shape of Superior Talar Dome: A Cadaver Measurement Based on Chinese Population

Understanding the shape of superior talar dome is essential for a better size compatibility between talar component of ankle implant and bone. The purpose of this study was to determine whether there were gender variations in (1) width (TW) and length (TL) of talus, as well as anterior width (DAW), middle width (DMW), posterior width (DPW), and length (DL) of superior talar dome; (2) differences between the DAW, DMW, and DPW; (3) the ratios between these parameters. Fifty-one cadaveric ankle specimens were included. Two observers measured all the specimens using vernier caliper. Intraclass correlation coefficients (ICCs) were used for intraobserver and interobserver reliability analysis and the reliability was thought to be good if the ICC>0.75. A two-tailed unpaired -test or the rank-sum test was used to investigate gender variations. A single-factor ANOVA was utilized to identify the differences between the width of the superior talar dome surface and p value of <0.05 was considered significant. Intraobserver and interobserver reliability were good. Significant gender variations were found, in which TW, TL, DAW, DMW, DPW, and DL of female specimens were much smaller than those of male. The width of talar dome linearly decreased from DAW to DPW; however, the linearly decreased rate from anterior to posterior width was bigger in female. Moreover, significant differences were found in DAW/DPW, DMW/DPW, DL/DAW, DL/DMW, and DL/DPW between male and female. Based on our result, there was no difference in the 2D shape of the whole talus instead gender variation existed in the 2D shape of superior talar dome between male and female. The current 2D data could contribute to figure out more suitable size of talar component for Chinese population and might indicate a gender-specific shape of bone-implant interface, which could reduce the potential bone-component incompatibility when performing ankle replacement using standard component.