Bio-Modelling, Design, Analyses and Prototyping of Patient-Specific Medical Implants Using CT Scan Data

Conventional knee and cranial implant systems have been in use for many years for patients suffering from arthritis and skull fractures. These implants are commercially available in standard sizes. However, the increasing number of failure occurrences and the demand to increase the longevity of implants has directed towards the need for patient-specific implant designs. This work combines clinical imaging, computer-aided design, analyses, and manufacturing to develop patient-specific knee and cranial implant that can accommodate the variations in size and shape among individuals. Patient-specific stacked image data based on Computed Tomography (CT) is used to build the surface 3D models using commercial medical image processing software. This 3D files represented in STL format are converted to IGES format and transferred into CAD environment to model and design the implants. The modeled implants are then subjected to structural, fatigue and impact analyses using finite element method based on Co-Cr and titanium alloy as the implant material. The results revealed that the designed knee implant could last about 10
⁸
cycles which could be translated to more than 50 years for an average built person. The designed cranial implant can withstand high impact loads up to deceleration of five times acceleration due to gravity. Finally, the developed knee and cranial implant prototypes are fabricated using Fused Model Deposition (FDM) based additive manufacturing method for the design approval of a competent medical practitioner.