1. Section of Orthopaedic Rehabilitation, Division of Orthopaedic Surgery, Oslo University Hospital, Oslo, Norway;
2. Institute of Health and Society, University of Oslo, Oslo, Norway;
3. Department of Physical Medicine and Rehabilitation, Division of Clinical Neuro-science, Oslo University Hospital, Oslo, Norway;
4. Faculty of Health Sciences, Oslo and Akershus University, College of Applied Sciences, Oslo, Norway