Roland Becker1, Reha Tandogan2, Bruno Violante3. 1. Department of Orthopedics and Traumatology, Centre of Joint Replacement, Hospital Brandenburg, Medical School "Theodor Fontane", Hochstrasse 2, 14770, Brandenburg/Havel, Germany. r.becker@klinikum-brandenburg.de. 2. Cankaya Orthopedics, Cinnah caddesi, 51-4 Çankaya, 06680, Ankara, Turkey. 3. Orthopaedic Department, Istituti Clinici Zucchi, Monza, Italy.