1. Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, N.T., Hong Kong.
2. Department of Orthopaedics and Traumatology, North District Hospital, 9 Po Kin Road, Sheung Shui, Hong Kong.
3. Beijing Jishuitan Hospital, 35# Xinjiekou East Street, 100035 Xicheng District, Beijing, China.