1. ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland;
2. Department of Orthopedic Surgery, Bern University Hospital, Bern, Switzerland;
3. Department for BioMedical Research, University of Bern, Bern, Switzerland;
4. Center for Advanced Orthopedic Studies, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA