1. Department of Orthopaedic Surgery, Østfold Hospital Trust, Graalum, Norway (IKS)
2. Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway (IKS)
3. Department of Orthopaedic Surgery, Bærum Hospital, Vestre Viken Hospital Trust, Baerum, Norway (MRA)
4. Division of Orthopaedic Surgery, Oslo University Hospital, Oslo, Norway (EEH)