Article History
Received: 23 December 2019
Revised: 18 January 2020
Accepted: 12 February 2020
First Online: 4 March 2020
Conflict of interest
: The study was financed by institutional grants. SK is consultant for Nexstim Plc (Helsinki, Finland) and Spineart Germany (Frankfurt, Germany) and received honoraria from Medtronic (Meerbusch, Germany) and Carl Zeiss Meditec (Oberkochen, Germany). SK and BM received research grants and are consultants for Brainlab AG (Munich, Germany). BM received honoraria, consulting fees, and research grants from Medtronic (Meerbusch, Germany), icotec ag (Altstätten, Switzerland), and Relievant Medsystems Inc., Sunnyvale, CA, USA), honoraria and research grants from Ulrich Medical (Ulm, Germany), honoraria and consulting fees from Spineart Deutschland GmbH (Frankfurt, Germany) and DePuy Synthes (West Chester, PA, USA), and royalties from Spineart Deutschland GmbH (Frankfurt, Germany). However, all authors declare that they have no conflict of interest regarding the materials used or the results presented in this study.
: Ethics committee registration number 42/16.