1. Department of Orthopaedic Surgery, University of Illinois, Chicago, Illinois, United States
2. Rush University Medical Center, Minimally Invasive Spine Institute, Chicago, Illinois, United States
3. Orthopaedic Surgery, Spine Colorado, Durango, Colorado, United States
4. Department of Neurosurgery, Duke University, Durham, North Carolina, United States
5. Department of Neurosurgery, University of California San Francisco Medical Center, San Francisco, California, United States