ZrO2-toughened Al2O3-based near-net shaped femoral head: Unique fabrication approach, 3D microstructure, burst strength and muscle cell response

The development of reliable biomedical devices demands the use of an integrated manufacturing protocol with comprehensive understanding of prototype characterization in terms of 3D microstructural analysis along with biocompatibility. While addressing these issues for ZrO2 (3 mol% Y2O3 stabilized)-toughened Al2O3-based femoral head prototypes, the present work reports a unique fabrication protocol involving a sequence of uniaxial compaction followed by pre-sintering, machining, final sintering and polishing to ensure dimensional tolerance with respect to the design of patient-specific femoral head. The prototypes are characterized by a clinically relevant surface finish (R-a similar to 0.2 mu m) with good geometric circularity (+/- 50 mu m). Extensive mu CT analysis at different regions of interest confirms a homogeneous distribution and 3D spatial orientation of ZrO2 across the volume of the defect -free prototype. Further, an in vitro cell culture with a murine myoblast cell line (C2C12) over a period of 72 h showed an increase in the number of mitochondrially-active cells and good cellular attachment with oriented cellular bridge formation, which confirms the excellent cytocompatibility. The as-machined ZTA femoral heads fracture at a load of 15.3 kN during burst tests, conducted following ISO guidelines. Taken together, this novel fabrication approach can be effectively utilised in the development of near-net shaped bioceramic-based femoral ball heads. (C) 2017 Published by Elsevier B.V.