1. Department of Orthopaedics, Schulthess Clinic, Lengghalde 2, 8008 Zürich, Switzerland
2. Pediatric Orthopaedics, Schulthess Clinic, Lengghalde 2, 8008 Zürich, Switzerland
3. Clinica Orthopedica, Ospedale di Portogruaro, 30026 Portogruaro, Italy
4. Professor Emeritus, Faculty of Medicine, University of Berne, Murtenstrasse 11, 3008 Berne, Switzerland