Vogler, C
Gschwind, L
Coynel, D
Freytag, V
Milnik, A
Egli, T
Heck, A
de Quervain, D J-F
Papassotiropoulos, A
Article History
Received: 23 May 2014
Revised: 11 July 2014
Accepted: 26 July 2014
First Online: 9 September 2014
Competing interests
: The authors declare no conflict of interest.