Institute for Research in Operative Medicine, Faculty of Health, Department of Medicine, Witten/Herdecke University, Cologne, Germany. School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia. Department of Emergency Medicine, Alfred Health, Melbourne, Australia. Institute for Medical Statistics, University Medical Centre, Göttingen, Germany. Department of Traumatology, Orthopaedic Surgery and Sports Traumatology, Cologne-Merheim Medical Centre, Witten/Herdecke University, Campus Cologne-Merheim, Cologne, Germany.