1. Schulthess Clinic, Zurich, Switzerland
2. Spine Unit, Schulthess Clinic, Lengghalde 2, CH-8008 Zurich, Switzerland.
3. Orthopedic Clinic Bulovka, Praha, the Czech Republic
4. Office for Management in Medical Research, Teningen, Germany
5. Gothenburg Medical Center, Vastra Frölunda, Sweden
6. Department of Sport and Sport-Pedagogic, Pedagogic-University, Freiburg, Germany
7. Grasshoppers Football Club, Zurich, Switzerland