1. Rothman Orthopaedic Institute at Thomas Jefferson University, Philadelphia, PA, USA
2. Center for Spinal Surgery and Neurotraumatology, Berufsgenossenschaftliche Unfallklinik, Frankfurt am Main, Germany
3. Cajuru Hospital, Catholic University of Parana, Caritiba, Brazil
4. University Medical Center, Utrecht, Netherlands
5. Malteser Waldkrankenhaus St. Marien, Erlangen, Germany
6. Vancouver General Hospital, Vancouver, British Columbia, Canada
7. Harborview Medical Center, Seattle, WA, USA
8. Sonnenhofspital Bern, Bern, Switzerland
9. Department of Orthopaedic Surgery, Ganga Hospital, Coimbatore, Tamil Nadu, India