1. Oxford Orthopaedic Engineering Centre, Nuffield Orthopaedic Centre, Windmill Road, Headington, Oxford OX3 7LD, UK.
2. Royal Free Hospital School of Medicine, Rowland Hill Street, London NW3 2PF, UK.
3. Semelweiss University of Medicine, Budapest X1, Karolina út 27, 1113 Hungary.