1. Department of Orthopaedic Surgery, University of Utah, Salt Lake City, UT
2. Nancy E and Peter C Meinig School of Biomedical Engineering Cornell University, Ithaca, NY
3. Department of Orthopedic Surgery, Duke University, Durham, NC
4. Department Orthopedics and Rehabilitation, University of Iowa, Iowa City, IA; and
5. Department Orthopedics and Rehabilitation, Oregon Health and Science University, Portland, OR.