1. Faculty of Medicine, Imperial College London, Charing Cross Hospital, Fulham Palace Road, London W6 8RF, UK.
2. Tropical Surgery Research and Training Unit, Beit CURE Hospital, P. O. Box 36391, Lusaka, Zambia.
3. Department of Orthopaedics, Great Ormond Street Hospital, Great Ormond Street, London WC1N 3JH, UK.
4. Nuffield Department of Orthopaedic Surgery, Nuffield Orthopaedic Centre, Windmill Road, Headington, Oxford 0X3 7LD, UK.