Funding for this research was provided by:
Received: 29 October 2018
Accepted: 18 February 2019
First Online: 4 March 2019
Ethics approval and consent to participate
: The study was approved by each of the local ethics committees of the participating hospitals:Reinier de Graaf hospital: METC ZWH (NL46683.098.136/13–088).Harrogate and District Foundation Trust: NHS Health Research Authority, National Research Ethics Service (: 14/YH/0140).Orthopaedic Hospital Speising and Sigmund Freud Private University: Ethikkommission der Stadt Wien (EK 13–196-0913).All patients signed informed consent.
: Not applicable.
: Financial competing interest: The POLAR <b><i>study</i></b> is sponsored by Zimmer Biomet.
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