In this paper, a shape memory alloy (SMA) based, multifunctional smart implant for improved bone fracture healing is presented. In contrast to conventionally used medical implants such as intramedullary nails or bone plates supporting a fractured bone in a passive way, the developed smart implant has on the one hand the ability to work as a common stabilizing implant. On the other hand, the smart implant has the property to stimulate the fracture to improve the bone healing process by controlled contracting micro movements. The smart implant consists of one mechanism to change the stiffness of the implant and one mechanism for the active stimulation purpose. Both actuator mechanisms are realized with the help of Nitinol SMA actuator wires, that are suitable for medical applications because of their biocompatibility. In addition to their actuator property the smart “self-sensing” ability of the SMA wires is used to control the actuator movements.
This work focuses mainly on the development and the design of the smart implant prototype and the parts are produced via 3D rapid prototyping.