1. a Department of Bioengineering, Clemson University, Clemson, SC 29634, USA
2. b Department of Bioengineering, Clemson University, Clemson, SC 29634, USA
3. c Department of Bioengineering, Clemson University, Clemson, SC 29634, USA
4. d Johnson and Johnson Orthopaedics, Raynham, MA 02767, USA
5. e Shriner's Hospitals for Crippled Children, Greenville, SC 29605, USA