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