1 Department of Spinal Surgery, Qingdao Hospital, University of Health and Rehabilitation Sciences (Qingdao Municipal Hospital), Qingdao, People's Republic of China.
2 Department of Spinal Surgery, Qingdao Hospital, University of Health and Rehabilitation Sciences (Qingdao Municipal Hospital), Qingdao, People's Republic of China. Electronic address: dechun-w@163.com.