Good manufacturing practices-grade preformed ossicular prostheses from banked bone via computer numerically controlled micromilling

Objectives: The aim of this study was the fabrication of ossicular replacement prostheses (ORPs) from decellularized banked cortical bone via computer numerically controlled (CNC) ultraprecision micromilling, in order to obtain preformed clinical-grade tissue products, reproducing shape, size, and details perfectly comparable to those of synthetic devices. Methods: Banked femoral compact bone was used to fabricate partial and total ORPs via CNC micromilling according to Good Manufacturing Practices procedures. Drawings of ORPs with different shapes and sizes were uploaded to the computer interface, and different surface-finish parameters were tested. The obtained products underwent dimensional, weight, and surface characterizations. A histologic analysis was pursued to compare the bone matrix compactness of the produced ORPs to that of the ear ossicles. Results: Banked-bone ORPs were produced with high dimensional accuracy. Partial ORP weights averaged (+/- SD) 31.2 +/- 0.6 mg, and total ORP weights averaged 69.3 +/- 0.7 mg. The best-finish mode allowed microscale or nanoscale roughness free from machinery textures to be obtained. Finally, the histologic analysis confirmed that the extracellular matrix compactness of the produced ORPs was suitable for ossicular chain replacement. Conclusions: This study assesses the fabrication feasibility of novel banked-bone ORPs of extremely high dimensional accuracy. Such devices are aimed at combining the most favorable aspects of both synthetic (reproducibility, convenience, and biosafety) and biological replacements (total biocompatibility).