Funding for this research was provided by:
Sophies Minde Ortopedi
Received: 28 February 2019
Accepted: 16 December 2019
First Online: 8 January 2020
Ethics approval and consent to participate
: The study was approved by the Regional Committee for Medical and Health Research Ethics, section South-East and the Commissioner for the Protection of Privacy in Research, Oslo University Hospital. All participants and parents gave their written consent before inclusion into the CPOP register. The CPOP register have shared data and approved to the study.
: Not applicable.
: The authors declares that they have no competing interests.