1 *Rush University Medical Center, Chicago, Illinois †Stanford University, Stanford, California ‡University of Toronto, Toronto Western Hospital, Toronto, Ontario Canada §Department of Orthopaedic Surgery, Stanford University Stanford, California ¶Instituto de Patalogia da Coluna, São Paulo, Brazil ||Spine Midwest, St. Mary's Hospital, Jefferson City, Missouri **University of South Florida, Tampa, Florida ††Orthopaedic Specialists of Northwest Indiana, Munster, Indiana ‡‡University Medical Center, Las Vegas, Nevada §§Spine Colorado, Durango, Colorado ¶¶Ochsner Clinic Foundation, New Orleans, Louisiana ||||Northwest Orthopaedic Specialists, Spokane, Washington ***Lyerly Neurosurgery, Jacksonville, Florida †††Neo Spine, Puyallup, Washington ‡‡‡University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania §§§Keck Medicine, University of Southern California, Los Angeles, California.