1. Department of Orthopaedics, NYU Medical Center-Orthopaedic Hospital, New York, New York
2. Department of Orthopaedic Surgery, Hospital for Special Surgery, New York, New York
3. Department of Neurosurgery, University of Virginia Medical Center, Charlottesville, Virginia
4. Department of Orthopaedic Surgery, Denver International Spine Center, Denver, Colorado
5. Division of Orthopaedic Surgery, Scripps Clinic, La Jolla, California
6. Department of Neurosurgery, University of Illinois at Chicago, Chicago, Illinois
7. Department of Orthopaedics, University of California, San Francisco, California
8. Department of Orthopaedics, SUNY Downstate Medical Center, Brooklyn, New York
9. Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland
10. Department of Orthopaedic Surgery, University of California, Davis, Sacramento, California
11. Department of Orthopaedics, University of Kansas Medical Center, Kansas City, Kansas
12. Department of Orthopaedics, Swedish Neuroscience Institute, Seattle, Washington