Text and Data Mining valid from 2019-10-24
Received: 7 April 2019
Accepted: 17 September 2019
First Online: 24 October 2019
Compliance with ethical standards
: PP has an education and training and consultancy agreement with Medtronic Sofamor Danek, USA. FS, PSS, and RV certify that they have no affiliations with or involvement in any organisation or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements) or non-financial interest (such as personal or professional relationships, affiliations, knowledge, or beliefs) in the subject matter or materials discussed in this manuscript.
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee (Comissão de Ética para a Saúde do Centro Hospitalar Universitário de São João) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. For this type of study, formal consent is not required.