1. KR Archer, PT, MS, DPT, is a PhD candidate, Center for Injury Research and Policy, Bloomberg School of Public Health, Johns Hopkins University, 624 North Broadway, Room 545, Baltimore, MD 21205 (USA).
2. RC Castillo, MS, is Assistant Scientist, Center for Injury Research and Policy, Department of Health Policy and Management, Bloomberg School of Public Health, Johns Hopkins University
3. EJ MacKenzie, PhD, is Fred and Julie Soper Professor and Chair, Department of Health Policy and Management, Bloomberg School of Public Health, Johns Hopkins University
4. MJ Bosse, MD, is Director and Clinical Research and Orthopaedic Traumatologist, Department of Orthopaedic Surgery, Carolinas Medical Center, Charlotte, NC
5. The LEAP Study Group is: Ellen J MacKenzie, PhD; Michael J Bosse, MD; James F Kellam, MD; Andrew R Burgess, MD; Lawrence X Webb, MD; Marc F Swiontkowski, MD; Roy Sanders, MD; Alan L Jones, MD; Mark P McAndrew, MD; Brendan Patterson, MD; Melissa L McCarthy, ScD; Thomas G Travison, PhD; and Renan C Castillo, MS.