1. School of Engineering, Brown University, Providence, RI 02912 e-mail:
2. Associate Professor School of Engineering, Brown University, Providence, RI 02912 e-mail:
3. Mem. ASME Professor Department of Orthopaedics, Center for Biomedical Engineering, Brown University, Providence, RI 02912 e-mail:
4. Mem. ASME Assistant Professor School of Engineering, Brown University, Providence, RI 02912 e-mail: