[1] Univ Calgary, Foothills Med Ctr, 1403 29th ST NW, Calgary, AB T2N 2T9, Canada
[2] Canadian Spine Outcomes & Res Network, 10 Armstrong Cres POB 1053, Markdale, ON N0C 1H0, Canada
[3] Middlemore Hosp Orthopaed Dept, 100 Hosp Rd, Auckland 2025, New Zealand
[4] Dalhousie Univ, Halifax, NS B3H 4R2, Canada
[5] Canada East Spine Ctr, 555 Somerset St,Suite 200, St John, NB E2K 4X2, Canada
[6] Victoria Hosp, London Hlth Sci Ctr, 800 Commissioners Rd E,E1-317, London, ON N6A 5W9, Canada
[7] Western Univ, Schulich Sch Med, London, ON, Canada
[8] Univ Laval, CHU Quebec, Dept Surg, Div Neurosurg, 1401 18e Rue, Quebec City, PQ G1J 1Z4, Canada
[9] Toronto Western Hosp, 399 Bathurst St,East Wing 1-441, Toronto, ON M5T 2S8, Canada
[10] Univ Toronto, 494851 Traverston Rd, Markdale, ON N0C 1H0, Canada
[11] Univ Hlth Network, Toronto, ON, Canada
[12] Krembil Res Inst, Arthrit Program, Toronto, ON, Canada
[13] Univ British Columbia, Vancouver Gen Hosp, Blusson Spinal Cord Ctr, 6th Floor,818 West 10th Ave, Vancouver, BC V5Z 1M9, Canada