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.
2. Department of Orthopaedics and Rehabilitation, Walter Reed Army Medical Center, Washington, D.C.
3. Howard Hughes Medical Institute–National Institutes of Health Research Scholars Program, Bethesda, Maryland.