1. Department of Orthopaedics, The First Affiliated Hospital, Zhongshan University, Zhongshan 2 Road #58, 510080, Guangzhou, China.
2. University of Tampere, Kalevantie 4 33014, Tampere, Finland.
3. Coxa - Hospital for Joint Replacement, P. O. Box 652, 33101 Tampere, Finland.
4. Department of Medicine Helsinki University Central Hospital, PO Box 700 (Haartmaninkatu 8), Helsinki, FIN-00029, Finland.