1. Department of Medical UltrasoundAffiliated Hospital of Jiangsu University Zhenjiang 212001 P. R. China
2. State Key Lab of High Performance Ceramics and Superfine MicrostructureShanghai Institute of CeramicsChinese Academy of Sciences Shanghai 200050 P. R. China
3. Department of OrthopedicsNaval Medical Center of PLASecond Military Medical University Shanghai 200052 P. R. China