1. Johns Hopkins University School of Medicine , Baltimore, Maryland
2. Department of Physical Therapy and Athletic Training, University of Utah , Salt Lake City, Utah
3. Rehabilitation Services, Intermountain Healthcare , Salt Lake City, Utah
4. Department of Physical Therapy, University of Delaware , Newark, Delaware
5. Division of Epidemiology, University of Utah , Salt Lake City, Utah
6. Johns Hopkins University School of Medicine , Baltimore, MD