1. Orthopaedic Surgery, Keller Army Hospital, New York, New York, USA.
2. Uniformed Services University of the Health Sciences, Bethesda, Maryland, USA.
3. New England Musculoskeletal Institute, University of Connecticut Health Center, Farmington, Connecticut, USA.
4. Deployment Health Research Department, Naval Health Research Center, San Diego, California, USA.
5. Seattle Epidemiologic Research and Information Center, Veterans Affairs Puget Sound Health Care System, Seattle, Washington, USA.
6. Naval Hospital Camp Pendleton, Camp Pendleton, California, USA.
7. Analytic Services Inc, Arlington, Virginia, USA.