Section of Clinical Rheumatology, Kumamoto Shinto General Hospital, 1-17-27 Shinyashiki, Chuo-ku, Kumamoto, 862-8655, Japan. nakamura@k-shinto.or.jp. Section of Orthodeadic Surgery, Kumamoto Orthopaedic Hospital, Kumamoto, Japan. Section of Clinical Rheumatology, Kumamoto Shinto General Hospital, 1-17-27 Shinyashiki, Chuo-ku, Kumamoto, 862-8655, Japan. Department of Surgical Pathology, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Japan.