[1] Weill Cornell Med, Hosp Special Surg, Spine Care Inst, 535 East 70th St, New York, NY 10021 USA
[2] Lucerne Cantonal Hosp, Dept Spine Surg, Spitalstr, CH-6000 Luzern, Switzerland
[3] Charite Univ Med Berlin, Ctr Musculoskeletal Surg, Charitepl 1, D-10117 Berlin, Germany
[4] Free Univ Berlin, Humboldt Univ Berlin, Charitepl 1, D-10117 Berlin, Germany
[5] Weill Cornell Med Coll, 1300 York Ave, New York, NY 10065 USA
[6] Univ Hosp Dusseldorf, Dept Orthoped Surg & Traumatol, Moorenstr 5, D-40225 Dusseldorf, Germany
[7] Weill Cornell Med, Hosp Special Surg, Dept Radiol & Imaging, 535 East 70th St, New York, NY 10021 USA