1 Department of Occupational and Social Medicine, Georg-August-University of Goettingen, Robert-Koch-Straße 40, 37075, Göttingen, Germany. Gino.Steinmetz@med.uni-goettingen.de.
2 Department of Trauma, Orthopedics and Reconstructive Surgery, Georg-August-University of Goettingen, 37075, Göttingen, Germany.
3 Division of Orthopaedics, Department of Trauma and Orthopaedic Surgery, University Medical Center Hamburg-Eppendorf, 20521, Hamburg, Germany.
4 Division of Endocrinology, Department of Medicine, Mayo Clinic College of Medicine and Science, Rochester, MN, 55901, USA.