Text and Data Mining valid from 2019-09-06
Received: 19 May 2019
Accepted: 27 August 2019
First Online: 6 September 2019
Ethics approval and consent to participate
: This retrospective study was approved by the Ethics Committee and Institutional Review Board of Keio University Hospital (IRB No. 20160256, 20170241 and 20170111), and opt-out consent was performed for each patient on our Web site (ExternalRef removed). Opt-out consent relies on implicit consent, where willingness to participate is tacit or presumed, and can be retracted by active objection.
: Not applicable.
: Dr. Nobuyuki Fujita serves as members of editorial board of BMC Musculoskeletal Disorders.