Designing Precise Ossicular Chain Reconstruction with Finite Element Modelling

Abstract The disruption of the middle ear ossicles, specifically the incus, can occur due to various factors like infection, tumours, and trauma. This can lead to ossicular discontinuity, which causes conductive hearing loss (CHL). A commonly used therapeutic approach to address CHL is Ossicular Chain Reconstruction (OCR), which involves placing a prosthesis between the tympanic membrane (TM) and the stapes structure to restore hearing. However, current solutions for incus replacement in OCR have a high failure rate of around 40% within five years, mainly due to material biocompatibility, biomechanics, and prosthesis anchoring. To minimize extrusion and improve prosthesis stabilization, an implant customized to the patient's middle ear anatomy could utilise the protective effects and natural amplification of the native ossicular chain, while also eliminating direct contact with the malleus handle or TM. In this study, we developed and validated a novel Finite Element (FE) model for the middle ear to evaluate anatomically-modelled prosthetic incus, inspired by healthy incus geometry and made of different biomaterial candidates, including titanium, hydroxyapatite (HA), and tricalcium phosphate (TCP). The results of our biomechanical analyses indicate that the proposed FE model, which included the prosthetic incus, closely mimicked the normal middle ear vibration. This suggests that titanium, HA, and TCP may be useful materials for ossicular prostheses. Furthermore, our study highlights the potential of an anatomically modelled prosthetic incus as a promising option for OCR. This paper lays the foundation for designing personalized OCR using FE modelling, potentially leading to substantial improvements in hearing outcomes for patients.