Footnotes

• Twitter @lena_kbm

• Contributors All author has made substantial contributions to two or more of the following: (1) The conception and design of the study, or acquisition of data, or analysis and interpretation of data. (2) Drafting the article or revising it critically for important intellectual content. (3) Final approval of the version to be submitted.

• Funding The Oslo Sports Trauma Research Centre provided all funding for performing this study. The Oslo Sports Trauma Research Center has been established at the Norwegian School of Sport Sciences through generous grants from the Royal Norwegian Ministry of Culture, the South-Eastern Norway Regional Health Authority, the International Olympic Committee, the Norwegian Olympic Committee & Confederation of Sport and Norsk Tipping AS.

• Competing interests None declared.

• Patient and public involvement statement Study participants were not actively involved in the research design.

• Provenance and peer review Not commissioned; externally peer reviewed.