1. Department of Orthopaedic Surgery, Westfriesgasthuis, Hoorn - The Netherlands
2. Department of Orthopaedic Surgery, St. Anna Hospital, Geldrop - The Netherlands
3. Department of Orthopaedic Surgery, Reinier de Graaf Groep, Delft - The Netherlands
4. Department of Orthopaedic Surgery, Franciscus Hospital, Roosendaal - The Netherlands