Qin Wang, Xiaofeng Li*, Jing Luo, Li Zhang, Lihui Ma, Zhiqin Lv and Lijin Xue
* Corresponding author: Xiaofeng Li lixf2003@yahoo.com.cn
BMC Musculoskeletal Disorders 2012, 13:249 doi:10.1186/1471-2474-13-249