1. Department of Orthopedic Surgery, Washington University School of Medicine, St. Louis, Missouri;
2. Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia;
3. Denver International Spine Center, Denver, Colorado;
4. Department of Neurological Surgery, Duke University, Durham, North Carolina; and
5. Och Spine Hospital, Columbia University College of Physicians and Surgeons, New York, New York