1. Division of Orthopaedic Surgery, Oslo University Hospital, Rikshospitalet, Post Office Box 4956 Nydalen, 0424 Oslo, Norway
2. Division of Orthopaedic Surgery, Oslo University Hospital, Rikshospitalet, Post Office Box 4956 Nydalen, 0424 Oslo, Norway and Institute of Physiotherapy, Faculty of Health Sciences, Oslo and Akershus University College of Applied Sciences, 0130 Oslo, Norway
3. Division of Orthopaedic Surgery, Oslo University Hospital, Rikshospitalet, Post Office Box 4956 Nydalen, 0424 Oslo, Norway and Institute of Occupational Therapy, Prosthetics and Orthotics, Faculty of Health Sciences, Oslo and Akershus University College of Applied Sciences, 0130 Oslo, Norway
4. Division of Orthopaedic Surgery, Oslo University Hospital, Rikshospitalet, Post Office Box 4956 Nydalen, 0424 Oslo, Norway and Institute of Health and Society, Medical Faculty, University of Oslo, Oslo, Norway