1 Department of Orthopaedics, Sahlgrenska University Hospital, Sahlgrenska Academy, Gothenburg University, Göteborg, Sweden. jon.karlsson@telia.com.
2 Department of Orthopaedics and Traumatology, Hospital Brandenburg, Medical School Theodor, Fontane, Hochstrasse 26, 14770, Havel, Bradenburg, Germany.
3 Department of Orthopaedic Surgery and Traumatology, Kantonsspital Baselland (Bruderholz, Liestal, Laufen), Bruderholz, Switzerland.
4 University of Basel, Basel, Switzerland.
5 Orthopaedic Surgery and Bioengineering, UPMC Center for Sports Medicine, University of Pittsburgh, Pittsburgh, PA, USA.