Gender difference in bowing of the sagittal femoral morphology measurement using magnetic resonance imaging.

The importance of femoral sagittal bowing on total knee arthroplasty (TKA) has not been actively discussed. Femoral sagittal bowing can lead to cortex damage, fractures, or femoral malalignment. Therefore, the purpose of this study was to evaluate femoral sagittal bowing at different segments of the femur in the Korean population, and to discuss the implications on total knee arthroplasty. Differences in the morphology of femoral sagittal bowing for 978 patients-829 women and 148 men-were evaluated using magnetic resonance imaging. The angle between the femoral mechanical axis and the anterior cortex line was measured for all the patients. In addition, the gender difference in femoral sagittal bowing was investigated. The angle of femoral sagittal bowing with the mechanical axis was 2.8˚ ± 2.2˚. The angles for femoral sagittal bowing were 2.9˚ ± 2.2˚ and 2.3˚ ± 2.6˚ for females and males, respectively. Thus, a gender difference was found in the femoral sagittal bowing (p < 0.05). Excessive sagittal bowing of the femur can affect the final sagittal position of the femoral component, and this has implications for implant design selection. We recommend that surgeons accurately perform pre-operative evaluation of femoral bowing to prevent potential malalignment, rotation, and abnormal stresses between the femur and implant.