Received: 10 April 2017
Accepted: 5 June 2018
First Online: 18 July 2018
Ethics approval and consent to participate
: IRB approval has been obtained from the IRB of the AMC for the AMC and Flevoziekenhuis (W16_258 # 16.303), the Slotervaart Medical Center (U/16.130/P1654), the VUmc (2016.541).The IRB provided a waiver for requesting written informed consent as this study concerns an observational cohort only including questionnaires. For use of the radiographs verbal informed consent was declared sufficient by the local IRB and legal department.
: Not applicable.
: Dr. Haverkamp is a member of the Editorial Board of BMC Musculoskeletal Disorders.Dr. ir. L. Blankevoort has (pending) Zimmer-Biomet and Smith&Nephew research grants.
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