1. Cartilage Biology and Orthopaedics Branch, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, USA
2. Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
3. Department of Orthopaedic Surgery, George Washington University, Washington, D.C., USA