Lyle J. Micheli, MD, Clinical Professor, Department of Orthopedic Surgery, Harvard Medical School, Director, Division of Sports Medicine, Children’s Hospital Boston, O’Donnell Family Professor of Orthopedic Sports Medicine, Children’s Hospital Boston, Boston, MA, USA Laura Purcell, MSc, MD, FRCPC, FAAP, Dip Sport Med, Associate Clinical Professor, Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada