Modeling and Validation of Additively Manufactured Porous Nitinol Implants

Bone implants are long term solutions for bone loss. Currently, two issues have been identified as reducing the long term stability of bone implants. The first issue is stiffness mismatch between the implant and the surrounding bony structure. The current materials used for manufacturing bone implants are much stiffer than the surrounding host bone. The second issue concerns bone-implant integration; the fact is that the bone needs an appropriate surface on which to attach and accept or deliver a load. Additive manufacturing techniques using Nitinol may provide the ability to fabricate bone implants with predetermined pore size and stiffness. This work brings the concept of stiffness tailoring to reality, taking advantage of additive manufacturing technique to fabricate engineering porosity to modify the stiffness. Based on the simulation and test results, it is shown that implants can be made with the stiffness in the range of the stiffness of the bone. The same capabilities can be used to affect a rough surface onto which bone is more likely to attach.