1. Norton Leatherman Spine Center, Louisville, Kentucky;
2. Department of Neurological Surgery, Carolina Neurosurgery and Spine Associates and Neurological Institute, Carolinas Healthcare System, Charlotte, North Carolina;
3. American Academy of Orthopaedic Surgeons, Rosemont, Illinois;
4. Department of Neurological Surgery, Duke University Medical Center, Durham, North Carolina;
5. Department of Neurosurgery, Atlantic Neurosurgical Specialists, Morristown, New Jersey;
6. Department of Neurosurgery, University of Tennessee Health Sciences Center, Semmes-Murphey Neurologic & Spine Institute, Memphis, Tennessee;
7. Hospital for Special Surgery, New York, New York;
8. Department of Orthopaedics, University of Utah School of Medicine, Salt Lake City, Utah;
9. Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, Minnesota; and
10. Department of Neurosurgery, Mayo Clinic, Rochester, Minnesota