[1] Hosp Italian Buenos Aires, Orthopaed & Traumatol Dept, Inst Orthoped Carlos E Ottolenghi, Buenos Aires, DF, Argentina
[2] Hosp Clin Reg Concepcion, Dept Neurosurg, Concepcion, Chile
[3] Univ Passo, Dept Neurosurg, Passo Fundo, RS, Brazil
[4] Hosp Espanol Mendoza, Orthoped Dept, Spine Unit, Mendoza, Argentina
[5] Hosp Italiano Buenos Aires, Family & Community Med Div, Buenos Aires, DF, Argentina
[6] Univ Estadual Campinas, Dept Neurol, Campinas, Brazil
[7] Univ Estadual Campinas, Dept Orthoped, Campinas, Brazil
[8] AOSpine Latin Amer Res Study Grp, Curitiba, Parana, Brazil