1. Instistute of Biomechanics; TUHH Hamburg University of Technology; Denickestrasse 15 21073 Hamburg Germany
2. Institute for Product Engineering; University of Duisburg-Essen; Lotharstrasse 1 47057 Duisburg Germany
3. Department of Orthopaedic and Spine Surgery; Loretto Hospital; Mercystrasse 6-14 79100 Freiburg Germany
4. Orthopaedic Center Münsingen; Krankenhausweg 18a 3110 Münsingen Switzerland