[1] Wayne State Univ, Sch Med, 540 East Canfield St, Detroit, MI 48201 USA
[2] Univ Calif Irvine, Dept Orthopaed Surg, Orange, CA 92668 USA
[3] Univ Southern Calif, Dept Neurol Surg, Keck Sch Med, Los Angeles, CA USA
[4] Columbia Univ, Dept Neurosurg, New York, NY USA
[5] Univ Southern Calif, Keck Sch Med, Dept Anesthesiol, Los Angeles, CA USA
[6] William Carey Univ, Coll Osteopath Med, Hattiesburg, MS USA
[7] Amgen Inc, Thoasand Oaks, CA USA
[8] Univ Calif Irvine, Med Ctr, Dept Orthopaed Surg, Orange, CA USA
[9] Oakland Univ, William Beaumont Sch Med, Rochester, MI 48063 USA