1. School of Engineering Medicine Beihang University Beijing 100191 P. R. China
2. School of Materials Science and Engineering Peking University Beijing 100871 P. R. China
3. Department of Bone and Joint Surgery Department of Orthopedics Renji Hospital Shanghai Jiao Tong University School of Medicine Shanghai 200001 P. R. China
4. Department of Orthopedics Shanghai Key Laboratory of Orthopedic Implant Shanghai Ninth People's Hospital Shanghai Jiaotong University School of Medicine Shanghai 200011 P. R. China