Guoping Guan1, Chao Zhu2. 1. Department of Orthopedics, The Affiliated Jiangning Hospital with Nanjing Medical University, Nanjing, People's Republic of China. 2. Department of Orthopedics, The Affiliated Jiangning Hospital with Nanjing Medical University, Nanjing, People's Republic of China. zhuchao3808@sina.com.