Towards a Rigorous Approach to Designing a TemporoMandibular Joint Prosthesis. From Clinical Challenge to Numerical Prototype

The primary objective when designing an innovative medical device (MD) is to improve the patient's condition and autonomy. Normally, therefore, there must be a strong focus on continuous interaction with the human element. Despite this interaction, value analysis (VA) tools are in fact used very little at the design stage.We describe the procedure we have devised and the characterization studies that result when applying VA to the design of a radically innovative temporomandibular joint (TMJ) prosthesis.From needs analysis to general availability of the device, there are three main phases in developing an MD: design, clinical validation and production/marketing. In the design phase, functional and technical specifications are defined from which digital and/or physical prototypes are created.Our multidisciplinary team defined and prioritized service functions after first analyzing clinical need. Next it specified the performances of a healthy TMJ which had to be reproduced, and then devised the experimental methods to achieve this characterization.A finite element (FE) model of the jaw was created and validated. Using simulations, the FE model compared strains and displacements in the healthy and the implanted mandibles. We then considered the influence of the implant geometry, the connections between implant and bone tissue to guide our decisions when creating innovative technical solutions. A new patent is currently under analysis and registration.