1. The London Hip Unit, 4th Floor, 30 Devonshire Street, London W1G 6PU, UK.
2. The Royal National Orthopaedic Hospital, Stanmore, Middlesex HA7 4LP, UK.
3. MIS Laboratory, Department of Orthopaedic Surgery NYU Medical Center - Hospital for Joint Diseases, 301 East 17th Street, Manhattan, New York 10003, USA.