1. The Key Laboratory of Biomedical Information Engineering of Ministry of Education Xi'an Jiaotong University Xi'an 710049 P. R. China
2. Bioinspired Engineering and Biomechanics Center (BEBC) Xi'an Jiaotong University Xi'an 710049 P. R. China
3. School of Safety Science and Engineering Xi'an University of Science and Technology Xi'an 710054 P. R. China
4. Department of Engineering Mechanics School of Civil Engineering Wuhan University Wuhan 430072 P. R. China
5. Xijing Orthopaedics Hospital Fourth Military Medical University Xi'an 710032 P. R. China
6. Department of Neurosurgery Tangdu Hospital The Fourth Military Medical University Xi'an 710038 P. R. China
7. Department of Mechanical Engineering & Materials Science Washington University in St. Louis St. Louis MO 63130 USA
8. NSF Science and Technology Center for Engineering Mechanobiology Washington University in St. Louis St. Louis MO 63130 USA
9. Department of Neurological Surgery Washington University School of Medicine St. Louis MO 63130 USA