This study was supported by: Wakayama Medical Award for Young Researchers in 2014 to Keiji Nagata, H23-Choujyu-002 (Director, Toru Akune), H-25-Choujyu-007 (Director, Noriko Yoshimura), H25-Nanchitou (Men)-005 (Director, Sakae Tanaka), 201417014A (Director, Noriko Yoshimura), and H22-Choujyu-Wakate-007 (Director, Shigeyuki Muraki) from the Ministry of Health, Labour and Welfare; a Grant-in-Aid for Scientific Research (B26293139, B23390172 to Noriko Yoshimura, B2629333, C20591774 to Shigeyuki Muraki, C26462249 to Hiroshi Hashizume, C25462305 to Hiroshi Yamada); a Grant-in-Aid for Young Researchers (B25860448 to Yuyu Ishimoto, B26860419 to Ryohei Kagotani, B15K20013 to Hiroki Iwahashi); a Grant-in-Aid for Challenging Exploratory Research (15K15219 to Noriko Yoshimura, 26670307 to Shigeyuki Muraki, 24659666 to Hiroyuki Oka, 25670293 to Toru Akune) of JSPS KAKENHI grant; This study also was supported by grants from the Japan Osteoporosis Society (Noriko Yoshimura, Shigeyuki Muraki, Hiroyuki Oka, and Toru Akune), a grant from JA Kyosai Research Institute (Hiroyuki Oka), grants from Mitsui Sumitomo Insurance Welfare Foundation (Shigeyuki Muraki), and research aid from the Japanese Orthopaedic Association (JOA-Subsidized Science Project Research 2006-1 and 2010-2; Director, Hiroshi Kawaguchi). The study sponsors played no role in the study design, the collection, analysis, and interpretation of data, writing of the report, or the decision to submit the paper for publication. The corresponding author had full access to all the data and had the final decision to submit for publication. The authors wish to thank Dr. Takako Nojiri and Mr. Kazuhiro Hatanaka of the Gobo Public Health Centre; Dr. Naoki Hirabayashi of the Kawakami Clinic, Hidakagawa Town; Mrs. Tomoko Takijiri, Mrs. Kumiko Shinou, Mrs. Rie Takiguchi, Mrs. Kyoko Maeda, Ms. Ikuyo Ueyama, Mrs. Michiko Mori, Mrs. Hisayo Sugimoto, and other members of the public office in Hidakagawa Town; Dr. Shinji Matsuda of the Shingu Public Health Centre; and Mrs. Tamako Tsutsumi, Mrs. Kanami Maeda, Mr. Shoichi Shimoichi, Mrs. Megumi Takino, Mrs. Shuko Okada, Mrs. Kazuyo Setoh, Mrs. Chise Ryouno, Mrs. Miki Shimosaki, Mrs. Chika Yamaguchi, Mrs. Yuki Shimoji, and other members of the public office in Taiji Town for their assistance in locating and scheduling participants for examinations. We also thank Ms. Kyoko Yoshimura, Mrs. Toki Sakurai, and Mrs. Saeko Sahara for their assistance with data reduction and administration.