Claeson, Amy2016-08-192016-08-192015-12https://hdl.handle.net/11299/181707University of Minnesota Ph.D. dissertation. December 2015. Major: Biomedical Engineering. Advisor: Victor Barocas. 1 computer file (PDF); x, 117 pages.Two lumbar facet joints flank the central spinous processes on the posterior aspect of the spine, and lie at the same level as the intervertebral discs. The facet joint is composed of two rigid articular facets, one from each of the adjacent vertebrae, the ligamentum flavum, and the facet capsular ligament (FCL). The FCL spans the articular facets and facilitates posterior spine kinematics by both stabilizing and guiding the relative motion between the articular facets. The poster aspect of the FCL is composed of horizontally aligned type I collagen fiber bundles, while the anterior aspect is elastin-rich, giving the FCL both strength and flexibility. The lumbar FCL is densely innervated with mechanoreceptive, proprioceptive and nociceptive nerve endings that both propagate signals to and receive signals from the central nervous system. The FCL has a 3D geometry because of the curvature of the articular facets, and because it is a capsule, it has multiple attachment sites. During spinal flexion, the relative rotation and displacement of the articular facets creates a shear deformation across the lumbar FCL. FCL deformation under mechanical loading could activate any of the nerve endings to modulate position or elicit the perception of pain. Moreover, the combination of a 3D geometry, multiple attachment sites, 3D kinematics, and dual materials creates complicated deformations across the FCL. The lumbar FCL is an invaluable component to the facet joint from a functional, structural and neuronal standpoint, and there exists a gap in knowledge about the tissue-level mechanical response of the lumbar FCL. Therefore, the aim of this dissertation was to elucidate the effect of shear deformations on the kinematics and mechanical properties of the lumbar FCL, specifically the shear deformations that arise during spinal flexion.enfinite element modelingoptical coherence tomographyplanar biaxial extensionspinezygapophyseal jointThesis or Dissertation