[1] Aachen Univ Hosp, Dept Orthopaed & Trauma Surg, Aachen, Germany
[2] Martin Luther Univ Halle Wittenberg, Dept Orthoped & Trauma Surg, Halle, Germany
[3] Univ Witten Herdecke, Cologne Merheim Med Ctr CMMC, Dept Traumatol & Orthoped Surg, Cologne, Germany
[4] Herdecke Univ, St Elisabeth Hosp Herten, Fac Hlth Witten, Dept Orthoped & Trauma Surg, Herten, Germany
[5] Aachen Univ Hosp, Dept Orthopaed & Trauma Surg, Pauwelsstr 30, D-52074 Aachen, Germany