1. Department of Orthopedics , Graduate School of Medical Science, , 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566, Japan
2. Kyoto Prefectural University of Medicine , Graduate School of Medical Science, , 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566, Japan
3. Department of Mathematics and Statistics in Medical Sciences, Kyoto Prefectural University of Medicine , 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566, Japan
4. Department of Orthopaedics, Fukuchiyama City Hospital , 231 Atsunaka-cho, Fukuchiyama, Kyoto 620-8505, Japan