1. Department of Orthopaedic Surgery, David Geffen School of Medicine, University of California-Los Angeles (UCLA), Los Angeles
2. Department of Orthopaedic Surgery, University of California-San Francisco (UCSF), San Francisco, CA
3. Department of Orthopaedic Surgery, Northwestern University, Chicago, IL
4. Department of Orthopaedic Surgery, Stanford University, Stanford
5. Department of Neurological Surgery, UCSF, San Francisco, CA