Text and Data Mining valid from 2019-01-08
Received: 22 September 2018
Accepted: 21 December 2018
First Online: 8 January 2019
Ethics approval and consent to participate
: Ethics approval was not necessary for this retrospective analysis. All patients of our clinic sign a declaration form that their data can be used for research purpuses.
: Not applicable.
: The authors declare that they have no competing interests.
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