1. University of Pittsburgh, Department of Orthopaedic Surgery, Cartilage Restoration Center, Pittsburgh, Pennsylvania
2. University of Vermont College of Medicine, Department of Orthopaedics and Rehabilitation, McClure Musculoskeletal Research Center, Burlington, Vermont
3. The University of Iowa, Department of Orthopaedic Surgery, Iowa City, Iowa
4. Duke University, Department of Orthopaedics, Durham, North Carolina
5. Brigham and Women’s Hospital, Division of Rheumatology, Immunology and Allergy, Boston, Massachusetts
6. Hospital for Special Surgery, Department of Orthopaedic Surgery, New York, New York
7. Vanderbilt University, Department of Orthopaedic Surgery, Nashville, Tennessee
8. Orthopaedic Specialty Group, Fairfield, Connecticut