1. Department of Orthopaedics, Kantonsspital, CH-4410, Liestal, Switzerland.
2. Department of Rheumatology and Institute of Physical Medicine and Rehabilitation, University Hospital of Zurich, CH-8091 Zurich, Switzerland.
3. Europa Fachhlochschule Fresenius, University of Applied Sciences, Fachbereich, Gesundheit Limburger, Straσσe 2, 65510 Idstein, Germany.
4. Department of Orthopaedics, University Hospital Basel, CH-4031 Basel, Switzerland.
5. Department of Otorhinolaryngology