von Wolff, M .
Bruckner, T.
Strowitzki, T.
Germeyer, A.
Article History
Received: 4 April 2018
Accepted: 28 May 2018
First Online: 5 June 2018
Compliance with ethical standards
: As anonymized registry data were analysed, ethical approval was not required.
: The authors declare that they have no conflict of interest.