1. Department of Ultrasound National Clinical Research Center for Geriatrics West China Hospital College of Polymer Science and Engineering Sichuan University Chengdu 610041 China
2. Institute of Orthopedics The First Medical Center Chinese PLA General Hospital Beijing Key Lab of Regenerative Medicine in Orthopedics Key Laboratory of Musculoskeletal Trauma and War Injuries PLA No. 28 Fuxing Road, Haidian District Beijing 100853 China
3. State Key Laboratory of Polymer Materials Engineering Sichuan University Chengdu 610064 China
4. Department of Chemistry and Biochemistry Freie Universität Berlin Takustrasse 3 Berlin 14195 Germany