1. Orthopaedic Department; University Hospital of Basel; Basel Switzerland
2. Department of Orthopaedics; Harold K. Dunn Orthopaedic Research Laboratory; University of Utah; Salt Lake City UT USA
3. Department of Dermatology Venerology and Allergology; University Medical Center and Medical Faculty Mannheim; University of Heidelberg; Mannheim Germany
4. Department of Orthopaedics and Trauma Surgery; University of Bonn; Bonn Germany