1 Department of Orthopaedics and Sports Medicine, Erasmus Medical Center, Rotterdam, Zuid-Holland, The Netherlands r.devos@erasmusmc.nl.
2 Department of Orthopaedics and Sports Medicine, Erasmus Medical Center, Rotterdam, Zuid-Holland, The Netherlands.
3 Research Unit for General Practice in Aalborg, Department of Clinical Medicine, Aalborg Universitet Det Sundhedsvidenskabelige Fakultet, Aalborg, Denmark.
4 Department of Rheumatology, Leiden University Medical Center, Leiden, Zuid-Holland, The Netherlands.