1. Department of Orthopaedic Surgery
2. Department of Trauma Surgery Academic Medical Center, P. O. Box 22660, 1105 AZ Amsterdam, The Netherlands.
3. Department of General Surgery Albert Schweitzer Hospital, P. O. Box 333, 3300 Dordrecht, The Netherlands.
4. Department of Orthopaedic Surgery Tergooi Hospitals, P. O. Box 10016, 1201 DA Hilversum, Blaricum, The Netherlands.