Custom fabrication of composite tibial hemi-knee joint combining CAD/CAE/CAM techniques.

A custom fabrication approach combining computer-aided design (CAD), computer-aided engineering (CAE), and computer-aided manufacturing (CAM) techniques for constructing a novel composite tibial hemi-knee joint is presented. Anatomical modelling was used to provide the computer model with specific geometry for individuals and the finite element method (FEM) was adopted to understand the loading distribution on each component of the composite substitute. Rapid prototyping (RP) was employed to build the negative patterns, based on which the titanium alloy tibial tray and the porous artificial bone were custom fabricated through quick casting and powder sintering techniques. The results show that the titanium alloy component bears most of the loading while the artificial bone shares little, which could prevent it from fracturing in vivo. The final porous artificial bone has controllable microchannels (600 microm) and random micropores (100-200 microm), which ensures full interconnectivity and is expected to address the biological consideration. Clinical application demonstrates that the composite tibial hemi-knee joint has enough mechanical strength and can fit with the upper hemi-knee joint. This novel approach provides a new way to repair large bone defects in the loading sites.