1. Department of Neurological Surgery, Rush University Medical Center, Chicago, Illinois, USA;
2. Spine Institute of Louisiana, Shreveport, Louisiana, USA;
3. Department of Orthopedic Surgery, Scripps Health, La Jolla, California, USA;
4. Department of Neurosurgery, University of California, San Francisco, San Francisco, California, USA;
5. Department of Neurosurgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA;
6. Department of Neurosurgery, Barrow Neurological Institute, Phoenix, Arizona, USA;
7. Department of Neurological Surgery, Weill-Cornell Medical Center, New York, New York, USA;
8. Department of Neurological Surgery, University of Miami, Miami, Florida, USA;
9. Department of Neurosurgery, Hoag Specialty Clinic, Newport Beach, California, USA;
10. Department of Orthopaedics, Cedars-Sinai Medical Center, Los Angeles, California, USA;
11. Department of Neurosurgery, New York University, New York, New York, USA;
12. Department of Neurological Surgery, The Och Spine Hospital, Columbia University, New York, New York, USA