1. Swiss Paraplegic Research, Nottwil, Switzerland
2. Faculty of Health Sciences, University of Lucerne, Lucerne, Switzerland
3. Department of Orthopedic Surgery, University of Bern, Bern Inselspital, Bern, Switzerland
4. Institute of Sports Medicine, Swiss Paraplegic Centre Nottwil, Nottwil, Switzerland
5. Institute of Social and Preventive Medicine (ISPM), University of Bern, Bern, Switzerland