[1] Yonsei Univ, Spine & Spinal Cord Inst, Dept Neurosurg, Coll Med, 50-1 Yonsei Ro, Seoul 03722, South Korea
[2] Natl Def Med Coll, Dept Orthoped Surg, Tokorozawa, Saitama, Japan
[3] Keio Spine Res Grp, Tokyo, Japan
[4] Univ Calif San Francisco, Dept Neurol Surg, San Francisco, CA USA
[5] Hosp Special Surg, Spine Serv, 535 E 70th St, New York, NY 10021 USA
[6] Oregon Hlth & Sci Univ, Portland, OR 97201 USA
[7] Univ Kansas, Med Ctr, Dept Orthoped Surg, Kansas City, KS 66103 USA
[8] Univ Virginia, Med Ctr, Dept Neurosurg, Charlottesville, VA USA
[9] Rocky Mt Hosp Children, Dept Orthopaed Surg, Denver, CO USA
[10] Inha Univ, Inha Univ Hosp, Dept Orthoped Surg, Sch Med, 366 Seohae Daero, Incheon 22332, South Korea