1. *Center for Injury Research and Prevention, Children’s Hospital of Philadelphia, PA
2. †Division of Emergency Medicine, Children’s Hospital of Philadelphia, PA
3. ‡Department of Biostatistics, Epidemiology, and Informatics, University of Pennsylvania, Philadelphia
4. §School of Nursing, University of Pennsylvania, Philadelphia
5. ‖Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta
6. ¶Sports Medicine and Performance Center, Children’s Hospital of Philadelphia, PA