1. Center of Experimental Orthopaedics; Saarland University; Building 37-38 D-66421 Homburg/Saar Germany
2. Department of Orthopaedic Surgery; Saarland University Medical Center; Homburg/Saar Germany
3. Institute of Medical Biometry; Epidemiology and Medical Informatics; Saarland University Medical Center; Homburg/Saar Germany