[1] Washington Univ, Sch Med, Dept Orthoped Surg, St Louis, MO 63110 USA
[2] Hosp Special Surg, Dept Orthoped Surg, New York, NY 10021 USA
[3] Johns Hopkins Univ, Sch Med, Dept Neurol Surg, Baltimore, MD USA
[4] Univ Virginia, Sch Med, Dept Neurol Surg, Charlottesville, VA 22908 USA
[5] Rocky Mt Hosp Children, Denver, CO USA
[6] Univ Calif Davis, Dept Orthoped Surg, Sacramento, CA 95817 USA
[7] San Diego Ctr Spinal Disorders, La Jolla, CA USA
[8] Univ Kansas, Med Ctr, Dept Orthoped Surg, Kansas City, KS 66103 USA
[9] Oregon Hlth & Sci Univ, Dept Orthoped Surg, Portland, OR 97201 USA
[10] Univ Calgary, Sch Med, Dept Surg, Calgary, AB, Canada
[11] NYU, Sch Med, Dept Orthoped Surg, New York, NY USA