Finite element investigation of the effect of spina bifida on loading of the vertebral isthmus

Quah, Conal; Yeoman, Mark S.; Cizinauskas, Andrius; Cooper, Kevin; McNally, Donal; Boszczyk, Bronek

Abstract

Background: Spondylolysis (SL) of the lower lumbar spine is frequently associated with spina bifida occulta (SBO). There has not been any study that has demonstrated biomechanical or genetic predispositions to explain the coexistence of these two pathologies. In axial rotation, the intact vertebral arch allows torsional load to be shared between the facet joints. In SBO, the load cannot be shared across the arch, theoretically increasing the mechanical demand of the vertebral isthmus during combined axial loading and rotation when compared to the normal state.
Purpose: To test the hypothesis that fatigue failure limits will be exceeded in the case of a bifid arch, but not in the intact case, when the segment is subjected to complex loading corresponding to normal sporting activities.
Study Design: Descriptive Laboratory Study.
Methods: Finite element models of natural and SBO (L4-S1) including ligaments were loaded axially to 1kN and were combined with axial rotation of 3°. Bilateral stresses, alternating stresses and shear fatigue failure on intact and SBO L5 isthmus were assessed and compared.
Results: Under 1kN axial load, the von Mises stresses observed in SBO and in the intact cases were very similar (differences

Citation

Quah, C., Yeoman, M. S., Cizinauskas, A., Cooper, K., McNally, D., & Boszczyk, B. (2014). Finite element investigation of the effect of spina bifida on loading of the vertebral isthmus. Spine Journal, 14(4), https://doi.org/10.1016/j.spinee.2013.08.040

• Journal Article Type: Article
• Acceptance Date: Aug 23, 2013
• Online Publication Date: Nov 20, 2013
• Publication Date: Apr 1, 2014
• Deposit Date: Jul 29, 2016
• Publicly Available Date: Jul 29, 2016
• Journal: Spine Journal
• Print ISSN: 1529-9430
• Electronic ISSN: 1529-9430
• Publisher: Elsevier
• Peer Reviewed: Not Peer Reviewed
• Volume: 14
• Issue: 4
• DOI: https://doi.org/10.1016/j.spinee.2013.08.040
• Keywords: Spina bifida occulta; Spondylolysis; Finite element analysis; Pars interarticularis fatigue fracture; Lumbar spine; Laminectomy
• Public URL: https://nottingham-repository.worktribe.com/output/723910
• Publisher URL: http://www.sciencedirect.com/science/article/pii/S1529943013014873