Received: 5 December 2019
Accepted: 12 February 2020
First Online: 21 February 2020
Ethics approval and consent to participate
: This study was approved by the Medical Ethical Committee of the Tokyo Women’s Medical University (approval number: 4681). The informed consent form in this study is opt-out.
: Not applicable.
: KO is a paid speaker of Smith and Nephew, Inc., and Zimmer Biomet, Inc. The other authors declare that they have no competing interests.