Text and Data Mining valid from 2019-06-01
First Online: 6 June 2019
Compliance with ethical guidelines
: B.A. Akbarnia acts as consultant and receives royalties from Nuvasive, San Diego, USA. G.M. Mundis acts as consultant, receives royalties and has stocks in Nuvasive.
: For this article no studies with human participants or animals were performed by any of the authors. All studies performed were in accordance with the ethical standards indicated in each case.