[1] Univ Hosp, Dept Orthoped & Trauma Surg, Dusseldorf, Germany
[2] Univ Cologne, Med Fac, Dept Orthoped & Trauma Surg, Cologne, Germany
[3] St Remigius Hosp Leverkusen, Ctr Spine Surg, Leverkusen, Germany
[4] Charite Univ Med Berlin, Ctr Musculoskeletal Surg, Spine Dept, Berlin, Germany
[5] Univ Hosp Leipzig, Dept Orthopaed Trauma Surg & Plast Surg, Leipzig, Germany
[6] Dept Trauma & Reconstruct Surg, Halle, Germany
[7] Univ Hosp Jena, Dept Trauma Hand & Reconstruct Surg, Jena, Germany
[8] Waldkrankenhaus Erlangen, Ctr Spinal & Scoliosis Surg, Erlangen, Germany
[9] Paracelsus Private Med Univ Nuremberg, Dept Orthoped & Traumatol, Nurnberg, Germany