[1] Harvard Univ, Interfac Initiat Hlth Policy, 14 Story St,Fourth Floor, Cambridge, MA 02138 USA
[2] Boston Childrens Hosp, Div Sports Med, Micheli Ctr Sport Injury Prevent, Boston, MA USA
[3] Univ Washington, Dept Pediat, Seattle, WA 98195 USA
[4] Seattle Childrens Res Inst, Ctr Child Hlth Behav & Dev, Seattle, WA USA
[5] Univ Washington, Harborview Med Ctr, Harborview Injury Prevent & Res Ctr, Seattle, WA 98104 USA
[6] Univ Wisconsin, Dept Radiol, Madison, WI 53706 USA
[7] Boston Univ, Sch Med, Chron Traumat Encephalopathy Ctr, Boston, MA 02118 USA