1. Boston University Boston Massachusetts
2. VA Boston Healthcare System Brigham and Women's Hospital Boston Massachusetts
3. University of Michigan Ann Arbor Michigan
4. University Hospital Reykjavik Iceland
5. Mayo Clinic Rochester Minnesota
6. Massachusetts General Hospital Boston Massachusetts
7. Cleveland Clinic Cleveland Ohio
8. University Medical Center Groningen The Netherlands
9. Johns Hopkins University Baltimore Maryland
10. Duke University Durham North Carolina
11. Hospital for Special Surgery New York New York
12. University of Pennsylvania Philadelphia