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The Scientific World Journal
Volume 2012, Article ID 381814, 6 pages
http://dx.doi.org/10.1100/2012/381814
Research Article

Biomechanics of Lateral Interbody Spacers: Going Wider for Going Stiffer

1Instituto de Patologia da Coluna, 04101-000 São Paulo, SP, Brazil
2Department of Neurosurgery, University of San Diego, San Diego, CA 92103, USA
3NuVasive, Inc., San Diego, CA 92121, USA
4Southern Oregon Orthopedics, Medford, OR 97504, USA

Received 3 August 2012; Accepted 23 September 2012

Academic Editors: G. J. Hooper, A. V. Korompilias, and C. C. Niu

Copyright © 2012 Luiz Pimenta et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This study investigates the biomechanical stability of a large interbody spacer inserted by a lateral approach and compares the biomechanical differences with the more conventional transforaminal interbody fusion (TLIF), with and without supplemental pedicle screw (PS) fixation. Twenty-four L2-L3 functional spinal units (FSUs) were tested with three interbody cage options: (i) 18 mm XLIF cage, (ii) 26 mm XLIF cage, and (iii) 11 mm TLIF cage. Each spacer was tested without supplemental fixation, and with unilateral and bilateral PS fixation. Specimens were subjected to multidirectional nondestructive flexibility tests to 7.5 N·m. The range of motion (ROM) differences were first examined within the same group (per cage) using repeated-measures ANOVA, and then compared between cage groups. The 26 mm XLIF cage provided greater stability than the 18 mm XLIF cage with unilateral PS and 11 mm TLIF cage with bilateral PS. The 18 mm XLIF cage with unilateral PS provided greater stability than the 11 mm TLIF cage with bilateral PS. This study suggests that wider lateral spacers are biomechanically stable and offer the option to be used with less or even no supplemental fixation for interbody lumbar fusion.