Abstract: The present invention involves a system for interactively designing prosthetic implants using two x-ray images, for example two femoral x-rays for designing a hip implant. The x-rays are scanned into a computer which electronically stores and displays the representations of the images. The computer allows the user to select points on the representations which relate to the location of the hip implant, particularly the medullary canal and other related points. The selected points are associated and stored along with the electronically stored representations. Based on the medullary canal definition and other parameters, an implant topology is generated which may be displayed and templated for medical evaluation. The system allows for the points and other parameters to be altered for calculating another implant topology.