1. Department of Orthopaedic Surgery, University of Aachen Medical Center, Germany (DA, MT)
2. Department of Orthopaedic, Trauma and Hand Surgery, Florence Nightingale Hospital, Düsseldorf Germany (DF, MA-C)
3. Clinic for Foot and Ankle Surgery, Hessing Foundation, Augsburg, Germany (HW)
4. Department of Orthopaedic and Joint Surgery, Betaklinik Bonn, Bonn Germany (CW)