[1] Northwestern Univ, Dept Neurol Surg, Feinberg Sch Med, 676 N St Clair St,Suite 2210, Chicago, IL 60611 USA
[2] San Diego Ctr Spinal Disorders, La Jolla, CA USA
[3] Univ Calif Davis, Dept Orthopaed Surg, Sacramento, CA 95817 USA
[4] Oregon Hlth & Sci Univ, Dept Orthopaed Surg, Portland, OR 97201 USA
[5] Univ Calif San Francisco, Dept Orthopaed Surg, San Francisco, CA USA
[6] Univ Kansas, Med Ctr, Dept Orthopaed Surg, Kansas City, KS 66103 USA
[7] NYU, Hosp Joint Dis, Dept Orthopaed Surg, New York, NY USA
[8] Univ Calif San Francisco, Dept Neurol Surg, San Francisco, CA USA
[9] Rocky Mt Hosp Children, Denver, CO USA
[10] Univ Virginia Hlth Syst, Dept Neurosurg, Charlottesville, VA USA