[1] Royal Derby Hosp, Royal Derby Spinal Ctr, Uttoxeter Rd, Derby DE22 3NE, England
[2] Royal Victoria Hosp, Belfast Hlth & Social Care Trust, 274 Grosvenor Rd, Belfast BT12 6BA, Antrim, North Ireland
[3] Univ Toronto, Div Neurosurg, Toronto, ON, Canada
[4] Univ Toronto, Spine Program, Toronto, ON, Canada
[5] Univ Missouri, Missouri Orthopaed Inst, 1100 Virginia Ave, Columbia, MO 65212 USA
[6] Tech Univ Munich, Klinikum Rechts Isar, Dept Neurosurg, Ismaninger Str 22, D-81675 Munich, Germany
[7] Univ British Columbia, Vancouver, BC, Canada
[8] Univ Toronto, Dept Surg, Toronto, ON, Canada
[9] Sunnybrook Hlth Sci Ctr, 2075 Bayview Ave,Rm MG 371-B, Toronto, ON M4N 3M5, Canada
[10] Sunnybrook Hlth Sci Ctr, Orthopaed Surg, 2075 Bayview Ave,Rm MG 371-B, Toronto, ON M4N 3M5, Canada