1. 1Department of Neurosurgery, University of Toronto, Ontario, Canada;
2. 2Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia;
3. 3Departments of Health Services and
4. 4Department of Neurosurgery, University of Kansas, Kansas City, Kansas;
5. 5Department of Orthopaedic Surgery, Emory University, Atlanta, Georgia;
6. 6Department of Orthopaedic Surgery, Thomas Jefferson University, Philadelphia, Pennsylvania;
7. 7Department of Orthopaedics, University of Utah, Salt Lake City, Utah;
8. 8Center for Spinal Disorders, Spine Education and Research Institute, Denver, Colorado;
9. 15Orthopaedics, University of Washington, Seattle, Washington;
10. 9Department of Orthopedic Surgery, Indiana Spine Group, Indianapolis, Indiana;
11. 10Department of Orthopedic Surgery, New England Baptist Hospital, Boston;
12. 11Boston Spine Group, Newton, Massachusetts;
13. 12Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota;
14. 13Department of Neurosurgery, Spine Division, Johns Hopkins University, Baltimore, Maryland; and
15. 14Department of Orthopedic Surgery, Brigham and Women's Hospital, Boston, Massachusetts