Ossicular replacement prostheses from banked bone with ergonomic and functional geometry

This study shows the fabrication of innovative ossicular replacement prostheses (ORPs) based on banked cortical bone using computer numerically controlled ultraprecision micromilling, as a substantial improvement of "second generation" ORPs. Our aim is to combine optimal middle ear compatibility and surgical manageability in a single device, by releasing off-the-shelf homograft ORPs provided with the appealing features of synthetic ORPs, such as lightness, safety, measurement accuracy, surface decoration, and geometric plasticity. The new total ORP prototype was 13.1±0.1 mg, leading to 81% weight reduction with respect to the previous model. Surface motifs of the head plate were applied to prevent slipping and migration after surgery, as shown by finite element modeling analysis. In addition, bone ORPs were provided with holed head plates to facilitate their surgical positioning while reducing their mass. A comparative measurement of acoustic responses of bone against synthetic partial ORPs in the 250-8000 Hz frequency range demonstrated their superior behavior. This study showed that banked compact bone can be optimally manufactured, eventually enabling the fabrication of light, standardized, and highly performant ORPs. The new bone ORPs may represent the ideal combination of biocompatibility and technology which can ultimately accomplish unmet otosurgical needs.