1. Department of Rehabilitation Medicine; University Medical Centre Groningen; Groningen The Netherlands
2. Stichting Omega; Amsterdam The Netherlands
3. Rehabilitation Centre ‘Revalidatie Friesland’; Beetsterzwaag The Netherlands
4. Division of Orthopedics & Child Health Evaluative Sciences; The Hospital for Sick Children and Bloorview Research Institute University of Toronto; Toronto ON Canada
5. Department of Special Needs Education and Child Care; University of Groningen; Groningen The Netherlands