1. Department of Orthopaedic Surgery, Northwestern Feinberg School of Medicine, Chicago, Illinois, United States
2. Thomas Jefferson University, The Rothman Institute, Philadelphia, Pennsylvania, United States
3. Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota, United States
4. Department of Neurosurgery, Kansas University Medical Center, Kansas City, Kansas, United States
5. Department of Surgery, Division of Neurosurgery and Spinal Program, University of Toronto, Toronto, Canada
6. Department of Neurosurgery, Rush University Medical Center, Chicago, Illinois, United States
7. Department of Neurosurgery, Rhode Island Hospital, Providence, Rhode Island, United States
8. Departments of Orthopaedic and Neurological Surgery, Cleveland Clinic, Cleveland, Ohio, United States
9. Department of Neurosurgery, Orthopedics and Health Sciences, Mayo Clinic, Rochester, Minnesota, United States
10. Department of Neurological Surgery, Feinberg School of Medicine of Northwestern University, Chicago, Illinois, United States
11. Department of Orthopedic Surgery, The Spine Hospital at NY-Presbyterian, New York, New York, United States