1. Department of Trauma and Orthopedic Surgery, University Medical Center Hamburg-Eppendorf, D-20246 Hamburg, Germany
2. Clinic of Nephrology and Hypertension, Diabetes and Endocrinology, Otto-von-Guericke University, D-39120 Magdeburg, Germany
3. Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, D-20246 Hamburg, Germany