Enhancing ossicular chain reconstruction through finite element analysis and advanced additive manufacturing: a review

Middle ear ossicles transfer and amplify sound waves from the Tympanic Membrane (TM) to the inner ear and function as impedance transformers to overcome impedance mismatches between the outer air and cochlear fluid. Several factors, including trauma, otitis media, chronic middle ear disease, or cholesteatoma, can lead to ossicular erosion, causing conductive hearing loss (CHL). A common surgical approach to address ossicular erosion is Ossicular Chain Reconstruction (OCR), also known as ossiculoplasty, wherein a middle ear prosthesis is inserted in place of the damaged ossicle(s). Unfortunately, studies indicate poor long-term outcomes in OCR as current techniques fail to accurately reproduce the natural anatomy and function of the patients' middle ear, leading to excessive force transmission and prosthesis extrusion. One promising first-order approach is computational modelling paired with 3D printing, which allows multi-parametric control to optimise and fabricate ossicular implants customised to the patient's middle ear anatomy. This customisation approach holds the promise of enhancing hearing outcomes after prosthesis implantation, as it replicates the natural sound transmission mechanism and protective effect of the normal ossicles. There is a particular need for such an approach, given no clear standards exist for prosthesis optimisation, potentially affecting patient care and hearing outcomes. This paper provides a comprehensive review of various middle ear implants based on their materials and evaluates the feasibility of Finite Element Method (FEM)-based design and customisation of 3D printing for middle ear prostheses. To improve surgical outcomes, the optimisation of prosthesis design is crucial. Enhanced hearing restoration can be achieved through more efficient and personalised prosthesis designs, leveraging FE analysis and advanced additive manufacturing, notably 3D printing.