1. Department of Physical Medicine and Rehabilitation, University of Utah School of Medicine , Salt Lake City, Utah, USA
2. David Geffen School of Medicine at UCLA , Los Angeles, California, USA
3. Indiana Spine Group , Caramel, Indiana, USA
4. Department of Radiology, Massachusetts General Hospital, Harvard Medical School , Boston, Massachusetts, USA
5. Technomics Research LLC , Minneapolis, Minnesota, USA
6. Department of Orthopaedics, University of California San Francisco , San Francisco, California, USA