1Orthopaedic Research Laboratory, Departments of Mechanical Engineering and Orthopaedic Surgery, Columbia University, New York, NY 10032, USA
2Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Columbia College of Physicians & Surgeons, New York, NY 10032, USA
3Division of Orthopaedics, University of California, San Diego, La Jolla, CA 92093, USA