1. The Micheli Center for Sports Injury Prevention, Waltham, MA 02453, USA
2. Division of Sports Medicine, Department of Orthopaedics, Boston Children's Hospital, Boston, MA 02115, USA
3. Brain Injury Center, Boston Children's Hospital, Boston, MA 02115, USA
4. Sports Medicine Center, Children's Hospital Colorado & University of Colorado School of Medicine, Aurora, CO 80045, USA
5. Department of Physical Medicine & Rehabilitation, University of Colorado, Aurora, CO 80045, USA
6. Rehabilitation Medicine, Children's Hospital Colorado, Aurora, CO 80045, USA
7. Department of Physical Medicine & Rehabilitation, Harvard Medical School, Spaulding Rehabilitation Hospital, Boston, MA 02129, USA
8. MassGeneral Hospital for Children Sport Concussion Program, Boston, MA 02114, USA
9. Home Base, A Red Sox Foundation & Massachusetts General Hospital Program, Boston, MA 02129, USA
10. Department of Pediatrics & Orthopaedic Surgery, Harvard Medical School, Boston, MA 02115, USA