1. WGM Janssen, MD, is Rehabilitation Specialist, Department of Rehabilitation, University Hospital Rotterdam, Dr Molewaterplein 40, 3015 GD Rotterdam, the Netherlands.
2. HBJ Bussmann, PT, PhD, is Assistant Professor, Department of Rehabilitation, Erasmus University Rotterdam, Rotterdam, the Netherlands
3. HJ Stam, MD, PhD, is Rehabilitation Specialist, Professor and Head of the Department of Rehabilitation Medicine, University Hospital Rotterdam and Erasmus University Rotterdam