aDepartment of Trauma and Orthopedic Surgery, Cologne-Merheim Medical Center (CMMC)

bInstitute for Research in Operative Medicine (IFOM), University Witten/Herdecke, Campus Cologne-Merheim, Cologne, Germany

Correspondence to Marc Maegele, Department of Trauma and Orthopedic Surgery, Cologne-Merheim Medical Center (CMMC), Institute for Research in Operative Medicine (IFOM), University Witten/Herdecke, Ostmerheimerstr. 200, 51109 Cologne, Germany. Tel: +49 221 8907 13 614; e-mail: [email protected]