1. Department of Orthopaedic Surgery, Chang Gung Children Hospital, 5 Fu-Shing Road, Taoyuan, Taiwan.
2. Department of Orthopaedic Surgery, Alfred I. duPont Hospital for Children, 1600 Rockland Road, PO Box 269, Wilmington, Delaware 19899, USA.
3. School of Education, University of Delaware, 221B Willard Hall Education Building, Newark, Delaware 197161, USA.