1. Department of Neurosurgery, University of Utah, Salt Lake City, Utah;
2. Alan and Jacqueline Stuart Spine Research Center, Department of Neurosurgery, Lahey Clinic, Burlington, and Tufts University School of Medicine, Boston, Massachusetts;
3. Department of Neurosurgery, Icahn School of Medicine at Mount Sinai, New York, New York;
4. Bone and Joint Clinic of Houston, Houston, Texas;
5. Department of Neurosurgery, University of Wisconsin, Madison, Wisconsin;
6. Department of Orthopaedic Surgery, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, New York;
7. Center for Sports Medicine and Orthopaedics, Chattanooga, Tennessee;
8. Department of Neurological Surgery, University of California, San Francisco, California;
9. Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California;
10. Department of Neurosurgery, Brigham and Women's Hospital, Boston, Massachusetts; and
11. Department of Neurosurgery, Columbia University, New York, New York