1. Leiden University Medical Center; Department of Medical Decision Making; Postzone J10-s, room J10-88 P.O. Box 9600 Leiden Netherlands 2300 RC
2. Leiden University Medical Center; Department of Orthopaedics; PO Box 9600 Leiden Netherlands 2300 RC
3. Leiden University Medical Center; Department of Neurosurgery; PO Box 9600 Leiden Netherlands 2300 RC
4. Sint Maartenskliniek; Department of Research, Development and Education; PO Box 9011 Nijmegen Netherlands 6500 GM
5. Sint Maartenskliniek; Department of Orthopaedics; PO Box 9011 Nijmegen Netherlands 6500 GM