Funding for this research was provided by:
Deutsche Forschungsgemeinschaft (KN356/6-1)
Received: 23 August 2016
Accepted: 22 January 2018
First Online: 6 February 2018
Ethics approval and consent participate
: Ethical approval was obtained from the independent local ethics committee of the University of Ulm (approvals 112/2003, 268/2008 and 235/2015). Written consent was obtained from all patients prior to surgery.
: Not applicable.
: The authors declare that they have no competing interests.
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