This study describes a methodology for designing a short femoral stem, based on CT scan data, for young patients requiring a hip replacement. One advantage of using a short femoral stem is that it reduces the amount of surgery, conserving the greater trochanter and the femoral neck ring. Precise digital data of the internal femoral anatomy are necessary to develop new prosthetic implants using computer-aided design (CAD) techniques. Image processing and CAD Softwares were used to obtain a 3D reconstruction of the cortical bone and canal geometry, implant design, fit evaluation and 2D drawings. A short femoral stem can then be manufactured from this CAD model using computer aided manufacturing (CAM) techniques. The design procedures and rationales are explained. The fit of the stem was tested before clinical application, using virtual stem implantation so that predictable implant-related problems could be rectified. It was concluded that the designed short femoral stem matched the femoral cavities very well. The results indicate that the investigated method of designing a short femoral stem is practicable and very desirable for young patients.