1. Orthopedic Department, University of Regensburg, Bad Abbach, Germany
2. Institute of Medical Biometry and Epidemiology, Philipps-University Marburg, Germany
3. Co-ordinating Center for Clinical Trials, Philipps-University Marburg, Germany
4. Institute for Medical Psychology, Philipps-University Marburg, Germany
5. Clinic for Anesthesiology, University of Heidelberg, Germany
6. Clinic for Acupuncture, Düsseldorf, Germany