1. Department of Orthopedic Surgery; Washington University in St. Louis; 660 S. Euclid, Campus Box 8233 St. Louis 63103 Missouri
2. Department of Biomedical Engineering; Washington University in St. Louis; One Brookings Drive, Whitaker Hall, Campus Box 1097 St. Louis 63130 Missouri
3. Department of Mechanical Engineering and Materials Science; Washington University in St. Louis; St. Louis Missouri