1. Department of Orthopedic Surgery, Ålesund Hospital, Møre and Romsdal Hospital Trust, Norway
2. Kysthospitalet in Hagevik, Orthopedic Clinic, Haukeland University Hospital, Bergen, Norway
3. Department of Clinical Medicine, University of Bergen, Bergen, Norway
4. Department of Neurosurgery, Stavanger University Hospital, Norway
5. Department of Quality and Health Technology, University of Stavanger, Norway
6. Department of Orthopedics, Sahlgrenska University Hospital, Gothenburg, Sweden
7. Department of Orthopedics, Institute for Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Sweden