1. Department of Orthopaedics, Physical Medicine and Rehabilitation, Ludwig-Maximilians-University of Munich, Munich, Germany
2. Department for Spine Therapy, Sportclinic Stuttgart, Stuttgart, Germany
3. SRH Health Center, Bad Herrenalb, Germany
4. Orthopaedie Centrum 30, Fellbach, Germany
5. Neurochirurgische Klinik, Klinikum Karlsruhe, Karlsruhe, Germany
6. Bathildis Krankenhaus, Bad Pyrmont, Germany
7. Ruhr-University Bochum, Bochum, Germany