1. Seattle Science Foundation, Seattle, WA, USA
2. Department of Orthopedics and Trauma Surgery, BG University Hospital Bergmannsheil, Ruhr University Bochum, Bochum, Germany
3. Center for Spine Surgery and Pain Therapy, Center for Orthopedics and Traumatology of the St. Elisabeth Group–Catholic Hospitals Rhein-Ruhr, St. Anna Hospital Herne/Marien Hospital Herne University Hospital/Marien Hospital Witten, Herne, Germany