1. Department of Orthopedic Surgery, Akershus University Hospital, Lørenskog;
2. Institute of Clinical Medicine, Campus Ahus, University of Oslo, Oslo;
3. Health Services Research Unit, Akershus University Hospital, Lørenskog;
4. Norwegian Hip Fracture Register, Department of Orthopedic Surgery, Haukeland University Hospital, Bergen;
5. Department of Clinical Medicine (K1), University of Bergen, Bergen;
6. Department of Sports Medicine; Norwegian School of Sport Sciences, Oslo, Norway