1. Department of Orthopaedics, Aarhus University Hospital, Aarhus, Denmark
2. Department of Orthopaedics, University Clinic of Hand, Hip and Knee Surgery, Holstebro, Denmark
3. Department of Orthopaedic Surgery, Regional Hospital Horsens, Horsens, Denmark
4. Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark