Additive Manufacture for Medical Engineering
Lead Research Organisation:
Imperial College London
Department Name: Mechanical Engineering
Abstract
In orthopaedic surgery, we repair, reconstruct or replace parts of human joints. This requires fixing different types of implants to the bone. Conventional manufacture of orthopaedic implants has been from solid Titanium CoCrMo allloys or ceramics, which are many times stiffer than the bone. But bone is a material that responds to strain, and thus these materials have limitations. Exciting new work in our research group has proven that we can make additively manufactured (AM) lattice parts that are the same stiffness as bone and bone formation has been controlled in an animal model through the strain gradient it experiences. This could be a major breakthrough in orthopaedic implant design.
We will improve upon our findings to demonstrate control of bone strains and fixation for a compartmental knee replacement, prototype configuration, with additively manufactured lattice parts. So far in this project our aims have been set as extracting anisotropic stiffness of bone based on CT data, validating this in human cadaveric bone and additively manufacturing components which are matched to this.
In the past 4 months progress has been made in extracting fabric tensors and density data using MATLAB scripts from clinical CT data of human Femurs and Tibias. Scripts have also been written which employ methods found in literature to find stiffness tensors for all CT voxels based on fabric and density data. Next efforts will seek to generate specimen specific cutting guides for the removal of cores from bone and validate our current stiffness tensor scripts against micro-CT scans (the current gold standard) and cadaveric specimens, via multiaxial mechanical stiffness testing.
We will improve upon our findings to demonstrate control of bone strains and fixation for a compartmental knee replacement, prototype configuration, with additively manufactured lattice parts. So far in this project our aims have been set as extracting anisotropic stiffness of bone based on CT data, validating this in human cadaveric bone and additively manufacturing components which are matched to this.
In the past 4 months progress has been made in extracting fabric tensors and density data using MATLAB scripts from clinical CT data of human Femurs and Tibias. Scripts have also been written which employ methods found in literature to find stiffness tensors for all CT voxels based on fabric and density data. Next efforts will seek to generate specimen specific cutting guides for the removal of cores from bone and validate our current stiffness tensor scripts against micro-CT scans (the current gold standard) and cadaveric specimens, via multiaxial mechanical stiffness testing.
