In vitro experiment of the modular orthopedic plate based on Nitinol, used for human radius bone fractures

Shape memory alloys (SMAs) and in particular Ni-Ti alloys are commonly used in bioengineering applications as they join important qualities as resistance to corrosion, biocompatibility, fatigue resistance, MR compatibility, kink resistance with two unique thermo-mechanical behaviors: the shape memory effect and the pseudoelastic effect. They allow Ni-Ti devices to undergo large mechanically induced deformations and then to recover the original shape by thermal loading or simply by mechanical unloading. Diaphyseal fractures of the radius and ulna present specific problems not encountered in the treatment of fractures of the shafts of other long bones. The adaptive modular implants based on smart materials represent a superior solution in the osteosynthesis of the fractured bones over the conventional implants known so far. To realize the model of the implant module we used SolidWorks software. The small sizes of the modules enable the surgeon to make small incisions, using surgical techniques minimally invasive, having the following advantages: reduction of soft tissues destruction; eliminating intra-operator infections; reduction of blood losses; the reduction of infection risk; the reduction of the healing time. Numerical simulations of the virtual modular implant are realized using Visual Nastran software. The stress diagrams, the displacements diagram and the strain diagram are obtained. An in vitro experiment is made, simulating the osteosynthesis of a transverse diaphyseal fracture of human radius bone. The kinematical parameters diagrams of the staple are obtained, using SIMI Motion video capture system. The experimental diagram force-displacement is obtained.