1. Department of Orthopaedic Surgery, University Medical Centre Groningen, Groningen, Netherlands
2. University Center for Geriatric Medicine, University of Groningen, University Medical Center Groningen, Groningen, Netherlands
3. Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA
4. Department of Orthopaedic Surgery, University Medical Centre Utrecht, University of Utrecht, Utrecht, Netherlands
5. Department of Engineering Systems & Services, Faculty Technology Policy and Management, Delft University of Technology, Delft, Netherlands
6. Department of Orthopaedic Trauma Surgery, Flinders Medical Center, Flinders University, Adelaide, Australia