1. Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts; Department of Orthopaedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts
2. Department of Orthopaedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts
3. Department of Orthopaedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; Department of Orthopedic Surgery, University of Vienna, Vienna, Austria
4. Department of Orthopaedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; Rehabilitation Engineering Research and Development, West Roxbury Veterans Administration Medical Center, West Roxbury, Massachusetts