1. Department of Biomedical Data Sciences, Section Medical Decision Making, Leiden University Medical Center , Albinusdreef 2, Leiden 2333 ZA, the Netherlands
2. Zorg & Zekerheid , Haagse Schouwweg 12, Leiden 2332 KG, the Netherlands
3. Department of Orthopaedics, Leiden University Medical Center , Albinusdreef 2, Leiden 2333 ZA, the Netherlands