1. Rothman Institute at Thomas Jefferson University, Philadelphia, PA, USA
2. Department of Orthopedic Surgery, University Medical Center, University of Utrecht, Utrecht, the Netherlands
3. University of British Columbia, Vancouver, BC, Canada
4. Center for Spinal and Scoliosis Surgery, Malteser Waldkrankenhaus St. Marien, Erlangen
5. Department of Orthopedics and Traumatology, Paracelsus Private Medical University Nuremberg, Nuremberg, Germany