1 Division of Biokinesiology and Physical Therapy, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, California.
2 Los Angeles, California.
3 UCLA Intervention Program, Department of Pediatrics and Center for Cerebral Palsy at UCLA/Orthopaedic Institute for Children, Department of Orthopaedic Surgery and Department of Neurology, University of California, Los Angeles, Los Angeles, California.