Received: 21 October 2019
Accepted: 2 January 2020
First Online: 17 January 2020
Compliance with Ethical Standards
: Alexander J. Butler, MD, and G. Damian Brusko, BS, declare that they have no conflicts of interest. Michael Y. Wang, MD, reports royalties from DePuy-Synthes Spine, Inc., Children’s Hospital of Los Angeles, Springer Publishing, and Quality Medical Publishing; personal fees as a consultant from DePuy-Synthes Spine, Inc., JoiMax USA, K2M, and Aesculap Spine; advisory board membership for Vallum; stock in Spinicity and Innovative Surgical Devices; and grants from the US Department of Defense.
: All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2013.
: Informed consent was waived from all patients for being included in this study.
: Disclosure forms provided by the authors are available with the online version of this article.