Design and manufacturing of the human bone endoprostheses using computer-aided systems

Basing on the results obtained previously, the authors present both research and application issues of modern computer-aided design and manufacturing of human bone replacements (endoprostheses). The first stage of the procedure consists in identifying the geometry (dimensions, shapes) and material (composition of the tissue, i.e. cortical and cancellous bone fractions) of the elements of human bone to be replaced with implants. For this purpose, the X-ray Computerized Tomography (CT) and Coordinate Measuring Machine (CMM) are used. In the second stage by means of a Computer-Aided Design (CAD) system, a geometrical model of the bone under consideration is constructed, representing both external and internal (marrow cavity) shapes and areas of cortical and cancellous bones. At this stage it is possible to change
the shape of the endoprosthesis to fit exactly the patient's anatomic features. Also, the strength can be estimated, using the Finite Element Method package included in the Computer-Aided Engineering (CAE) system, and the system can be modified if necessary. At the third stage, using the Computer-Aided Manufacturing (CAM) system, the technological process is designed and then the endoprosthesis, e.g. using a Computer Numerical Controlled (CNC) machine, is manufactured.