1. Department of Orthopaedics, Institute of Clinical Sciences, University of Gothenburg, Gothenburg, Sweden.
2. Department of Health and Rehabilitation, Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden.
3. Orkuhusid Orthopaedic Clinic, Reykjavik, Iceland.
4. Division of Orthopaedic Surgery, Department of Surgery, McMaster University, Hamilton, Ontario, Canada.