1. Department of Orthopaedic Surgery, Osaka City University Medical School, 1-5-7 Asahi-machi, Abeno-ku, Osaka 545, Japan.
2. Princess Alexandra Hospital, Ipswich Road, Woolloongabba, Brisbane 4011, Australia.
3. Bone and Joint Research Unit, The Royal London Hospital Medical College, 25–29 Ashfield Street, London E1 2AD, UK.