1. Department of Epidemiology and Biostatistics; School of Public Health; Xi'an Jiaotong University Health Science Center; No. 76 West Yanta Road Xi'an Shaanxi 710061 China
2. Department of Orthopedics and Traumatology; Xi'an Hospital of Traditional Chinese Medicine; Xi'an China
3. Department of Traditional Chinese Medicine Orthopedics Diagnosis and Treatment Center; Xi'an Honghui Hospital; Xi'an China
4. Department of Public Health; Shaanxi University of Chinese Medicine; Xi'an China