1. Department of Materials EngineeringSchool of Engineering, The University of TokyoBunkyo‐ku Tokyo113‐8656 Japan
2. Division of Science for Joint ReconstructionGraduate School of Medicine, The University of TokyoBunkyo‐ku Tokyo113‐8655 Japan
3. Medical R&D CenterCorporate R&D Group, KYOCERA CorporationYodogawa‐ku Osaka532‐0003 Japan
4. Materials Research and Development LaboratoryJapan Fine Ceramics CenterAtsuta‐ku Nagoya456‐8587 Japan
5. Department of Orthopaedic SurgeryFaculty of Medicine, The University of TokyoBunkyo‐ku Tokyo113‐8655 Japan