[1] Ulm Univ, Univ Hosp Ulm, Trauma Res Ctr Ulm, Inst Orthopaed Res & Biomech, Helmholtzstr 14, D-89081 Ulm, Germany
[2] IRCCS Ist Ortoped Galeazzi, Milan, Italy
[3] Rush Univ, Med Ctr, Dept Orthopaed Surg, Chicago, IL 60612 USA
[4] Rush Univ, Med Ctr, Int Spine Res & Innovat Initiat, Chicago, IL 60612 USA
[5] Univ Hosp Ulm, Dept Diagnost & Intervent Radiol, Ulm, Germany