1. Warren Alpert Medical School, Brown University, Providence, Rhode Island
2. Albany Medical College, Albany, New York
3. Department of Orthopedic Surgery, Warren Alpert Medical School, Brown University, Providence, Rhode Island
4. Hospital for Special Surgery, New York, NY
5. Texas Back Institute, Plano, Texas
6. Department of Neurosurgery, Warren Alpert Medical School, Brown University, Providence, Rhode Island