1. Department of Neurosurgery, University of Virginia Health System, Charlottesville, Virginia;
2. Departments of Neurosurgery and Orthopedic Surgery, Duke University Medical Center, Durham, North Carolina;
3. Department of Orthopedic Surgery, Washington University School of Medicine, St. Louis, Missouri;
4. Department of Medicine, Dartmouth Medical School, Hanover, New Hampshire;
5. Department of Neurosurgery, University of California, San Francisco, California;
6. Denver International Spine Center, Presbyterian St. Luke’s/Rocky Mountain Hospital for Children, Denver, Colorado; and
7. Hospital for Special Surgery, New York, New York