1. Department of Physical Therapy, University of Iceland, Saemundargata 2, 101 Reykjavík, Iceland
2. Physiotherapy Garðabær, Garðaflöt 16-18, 210 Garðabær, Iceland
3. Department of orthopaedics, Landspitali University Hospital, Fossvogur, 103 Reykjavík, Iceland
4. Gáski Physiotherapy, Bolholt 8, 105 Reykjavik, Iceland