Christoph-E Heyde1
, Johannes K Fakler1
, Erik Hasenboehler2
, Philip F Stahel2
, Thilo John1
, Yohan Robinson3
, Sven K Tschoeke1
and Ralph Kayser1 
1Department of Trauma, Orthopedics, and Reconstructive Surgery, Charité, University Medical Center, Campus Benjamin Franklin, Hindenburgdamm 30, 12200 Berlin, Germany
2Department of Orthopedic Surgery, Denver Health Medical Center, University of Colorado, School of Medicine, 777 Bannock St, Denver, CO 80204, USA
3Department of Orthopaedics, Academic Hospital, Uppsala University, 751 52 Uppsala, Sweden