1. Division of Emergency Medicine, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA
2. Center for Injury Research and Prevention, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA
3. Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
4. Departments of Emergency Medicine and Pediatrics, Alpert Medical School of Brown University and Hasbro Children’s Hospital, Providence, RI, USA
5. Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, PA, USA
6. Sports Medicine and Performance Center, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA