1. Faculty of Medicine and Health Sciences, Department of Health, Medicine and Caring Sciences, Linköping University , Linköping SE-581 83, Sweden
2. Faculty of Medicine and Health, School of Health Sciences, Örebro University , Örebro SE-701 82, Sweden
3. Department of Orthopaedics, Faculty of Medicine and Health, Örebro University , Örebro SE-701 82, Sweden
4. Faculty of Medicine and Health, University Health Care Research Center , Örebro SE-702 82, Sweden
5. Department of Public Health and Caring Sciences, Uppsala University , Box 564, SE-751 22, Uppsala, Sweden
6. Department of Clinical Science and Education, Södersjukhuset, Karolinska Institutet , Stockholm SE-118 83, Sweden
7. Department of Anaesthesia and Intensive Care, Södersjukhuset , Stockholm SE-118 83, Sweden