1. Departments of Orthopaedic Surgery, Nara Medical University, Kashihara City, Nara 634, Japan
2. Departments of Pathology, Nara Medical University, Kashihara City, Nara 634, Japan
3. STK Ceramics Laboratory Corp. No. ll-chome, Tsukisan-cho, Minato-ku, Nagoya 455, Japan