Funding for this research was provided by:
Japan Society for the Promotion of Science (26462290)
Received: 8 August 2017
Accepted: 13 November 2017
First Online: 6 December 2017
Ethics approval and consent to participate
: The study was approved by the Ethics Committee of Nagoya University School of Medicine (2017-0140). This is retrospective research including the information on synovial fluid obtained from the previous study. Therefore, we disclosed the study information at the site of related facilities instead of using a consent form according to committee procedure.
: Not applicable
: With the exception of RP, who is a consultant to IBEX Pharmaceuticals (manufacturers of the C2C assay kit) in Montreal, QC, Canada, the authors have no competing interests to report.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.