[1] Johns Hopkins Univ Hosp, Dept Neurosurg, Baltimore, MD USA
[2] St Josephs Hosp, Barrow Neurol Inst, Dept Neurosurg, Phoenix, AZ USA
[3] Univ Kansas, Med Ctr, Neurosurg, Kansas City, KS USA
[4] Rush Univ, Med Ctr, Dept Neurosurg, Chicago, IL USA
[5] Thomas Jefferson Univ Hosp, Dept Neurol Surg, Philadelphia, PA USA
[6] Musculoskeletal Educ & Res Ctr, Audubon, PA USA
[7] Drexel Univ, Sch Biomed Engn Sci & Hlth Syst, Philadelphia, PA USA
[8] Orange Cty Neurosurg Associates, Laguna Hills, CA USA
[9] Musculoskeletal Educ & Res Ctr MERC, 2560 Gen Armistead Ave, Audubon, PA 19403 USA