A Novel Semi-Constrained Design for Total Temporomandibular Joint Replacement: Dynamic Functional Finite Element Analysis

Background Total temporomandibular joint (TMJ) replacement is a critical intervention for end-stage joint pathologies or craniofacial resections involving the TMJ. However, most existing implant designs cannot overcome the problem of condyle migration or dislocation, especially in cases with extensive destruction of the mandibular muscle envelope or the cranial base. Moreover, most biomechanical studies focus on unilateral implants under static incisal clenching. For total TMJ replacement, the biomechanics of implants during dynamic mandibular motions remain poorly understood. Objective This study proposed and validated the biomechanical performance of a semi-constrained sliding hinged TMJ implant. Methods A 3D finite element model of the implant and reconstructed fibula segments was developed. To simulate realistic conditions, finite element analysis was conducted under 4 types of functional mandibular motions within the border envelope: incisal clenching, protrusion, lateral excursion and depression during mouth opening. The movements during a meal of the implant have also been simulated. Biomechanical responses of all implant components during these mandibular movements were analysed. Results Under most simulated movements, the stress and displacement levels of all components remained within safe material limits, confirming the design’s biomechanical stability. While transient, highly localised peak stresses occasionally were associated with extreme movements. The finite element analysis validated the biomechanical performance of the implant. The overall structural integrity of the implant was maintained throughout all mandibular daily activities. Conclusion This semi-constrained design ensures stable contact between condyle and disc components, replicating key biomechanical features of the native TMJ. This study supports this design as a promising solution wider clinical application. Clinical Relevance As the first and only TMJ implant design so far addressing the clinical challenge of condyle migration and dislocation, this proposed design could provide enhanced functional utility in complex maxillofacial reconstructions.