In this study, the femoral cancellous bone angle is estimated in order to design the femoral IM (Intra-Medullary) nail. Generally, it is various in size and curvature of femoral cancellous bone depending on patient’s body dimension and surgeon has difficulty in fitting this femoral IM nail to the patient in surgical procedure. In our study, Femoral lateral curve angle was estimated with more precise method based on CT image of the femur and utilize this information is utilized for the design of femoral IM nail for patients. Through this investigation, it may be possible to calculate each patient’s femoral cancellous bowing angle more precisely. If the bowing angle of the lateral images of each patient can be figured immediately through CT image, it will be easier to choose appropriate nail that is most suitable for each individual. More investigations need to be achieved by collecting more patient’s image data for femoral curvature.