1 Department of Orthopaedic Surgery and Traumatology, Copenhagen University Hospital Bispebjerg Frederiksberg, Denmark; Department of Clinical Medicine, University of Copenhagen, Denmark. soeren.overgaard@regionh.dk.
2 Section for Biostatistics and Evidence-Based Research, the Parker Institute, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark; Research Unit of Rheumatology, Department of Clinical Research, University of Southern Denmark, Odense University Hospital, Denmark.
3 Faculty of Medicine, Lund University, Lund, Sweden; Department of Orthopedics, Skåne University Hospital, Malmö, Sweden.
4 Department of Clinical Medicine, University of Copenhagen, Denmark; Department of Orthopaedic Surgery, Herlev and Gentofte University Hospital, Denmark.
5 Division of Orthopaedic Surgery, Oslo University Hospital, Oslo, Norway.
6 Department of Orthopaedics and Traumatology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland.
7 Elisabeth Tweesteden Hospital, Tilburg, the Netherlands; Department of Medical and Clinical Psychology, Tilburg University, Tilburg, the Netherlands.
8 Department of Orthopedic Surgery, Akershus UniversityHospital, Norway; Institute of Clinical Medicine, Campus Ahus, Faculty of Medicine, University of Oslo, Norway.
9 Department of Orthopaedics, Leiden University Medical Center, Leiden, The Netherlands; Dutch Arthroplasty Register (Landelijke Registratie Orthopedische Interventies), 's-Hertogenbosch, The Netherlands.
10 Department of Surgical Sciences, Orthopaedics and Hand Surgery, Uppsala University, Department Orthopaedics, Sweden.
11 Centre for Clinical Research, Uppsala University, Region Västmanland, Västerås, Sweden.
12 Division och Orthopedics and Biotechnology, Department of Clinical Science, Intervention and Technology (CLINTEC), Karolinska Institutet, Stockholm, Sweden; Trauma, Emergency Surgery and Orthopedics, Karolinska University Hospital, Stockholm, Sweden.
13 Department of Orthopaedics and Trauma, Tampere University Hospital, Tampere, Finland.