1. Department of Orthopaedics, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China
2. Department of Orthopaedics, Shanghai Bone Tumor Institute, Shanghai General Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200080, P.R. China
3. Division of Spine Surgery, Department of Orthopaedics, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065, P.R. China