1. Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, USA;
2. Auckland Bioengineering Institute & Department of Engineering Science, University of Auckland, Auckland, New Zealand;
3. Department of Bioengineering, Stanford University, Stanford, CA, USA;
4. Department of Radiology, Stanford University, Stanford, CA, USA;
5. Department of Orthopaedic Surgery, Stanford University, Stanford, CA, USA;
6. Mechanical Engineering Department, Stanford University, Stanford, CA, USA;
7. Musculoskeletal Research Laboratory, VA Palo Alto Health Care System, Palo Alto, CA, USA