1. Clintec, Karolinska Institutet, Stockholm and Departments of Surgery, Södertälje Hospital, Södertälje, Sweden
2. Uppsala University Hospital, Uppsala, Sweden
3. Mora Hospital, Mora, Sweden
4. Helsingborg Hospital, Helsingborg, Sweden
5. Karolinska University Hospital, Huddinge, Sweden
6. Department of Surgery, Oulu University Hospital, Oulu, Finland