[1] Emory Univ, Sch Med, Dept Orthopaed Surg, Emory Spine Ctr, Atlanta, GA 30329 USA
[2] Toronto Western Hosp, Div Neurosurg, Toronto, ON M5T 2S8, Canada
[3] Univ Toronto, Toronto Western Hosp, Toronto Western Res Inst, Div Orthopaed Surg,Spine Programme, Toronto, ON M5T 2S8, Canada
[4] Univ Washington, Harborview Med Ctr, Dept Orthopaed & Sports Med, Seattle, WA 98104 USA
[5] Univ Virginia, Dept Neurosurg, Charlottesville, VA USA
[6] Hosp Special Surg, Spine & Scoliosis Serv, New York, NY 10021 USA
[7] Spectrum Res Inc, Tacoma, WA USA
[8] Northwestern Univ, Feinberg Sch Med, Dept Orthopaed Surg, Chicago, IL 60611 USA
[9] Univ Toronto, Dept Phys Therapy, Toronto, ON, Canada