We wish to thank the staff of Muramatsu Health Centre for their help in data collection. We also thank the following institutions for providing us with necessary medical data: Igarashi Orthopaedic Clinic, Ishizone Clinic, Ito Clinic, Kaneko Clinic, Kasahara Clinic, Koyama Orthopaedic Clinic, Nanbugo General Hospital, Nanbugo Kosei Hospital, Murata Clinic, Takeda Clinic, Yamamura Orthopaedic Cli...