1. Department of Orthopaedics Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK.
2. Royal National Orthopaedic Hospital, Stanmore, Middlesex HA7 4LP, UK.
3. Royal London Hospital, Whitechapel, London E1 1BB, UK.
4. St George’s Hospital, Blackshaw Road, Tooting, London SW17 0QT.