Quantification of continuous in vivo flexion–extension kinematics and intervertebral strains

Nagel, Tina M.; Zitnay, Jared L.; Barocas, Victor H.; Nuckley, David J.

doi:10.1007/s00586-014-3195-0

Cited by 13 publications

(11 citation statements)

References 29 publications

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“…Further information on the fluoroscopic data sets and extraction of vertebral motion is given in Nagel et al [14]. Because facet joint kinematics during flexion cannot be measured directly on the sagittal plane fluoroscopic images, vertebral body motion at the posterior disc margin was used to define facet joint motion by treating the vertebrae as rigid bodies.…”

Section: Methodsmentioning

confidence: 99%

“…2 shows schematically how these inputs were obtained. Previously, our group published continuous in vivo vertebral kinematics during flexion and extension to quantify intervertebral margin strains [14], similar to data obtained by others [15,16]. From this data set, the facet joint motion was extrapolated from vertebral kinematics on sagittal plane.…”

Section: Introductionmentioning

confidence: 94%

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Computer simulation of lumbar flexion shows shear of the facet capsular ligament

Claeson

Barocas

2017

The Spine Journal

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BACKGROUND CONTEXT The lumbar facet capsular ligament (FCL) is a posterior spinal ligament with a complex structure and kinematic profile. The FCL has a curved geometry, multiple attachment sites, and preferentially aligned collagen fiber bundles on the posterior surface that are innervated with mechanoreceptive nerve endings. Spinal flexion induces three-dimensional (3D) deformations, requiring the FCL to maintain significant tensile and shear loads. Previous works aimed to study 3D facet joint kinematics during flexion, but to our knowledge none have reported localized FCL surface deformations likely created by this complex structure. PURPOSE The purpose of this study was to elucidate local deformations of both the posterior and anterior surfaces of the lumbar FCL to understand the distribution and magnitude of in-plane and through-plane deformations, including the prevalence of shear. STUDY DESIGN/SETTING The FCL anterior and posterior surface deformations were quantified through creation of a finite element model simulating facet joint flexion using a realistic geometry, physiological kinematics, and fitted constitutive material. METHODS Geometry was obtained from the micro-CT data of a healthy L3–L4 facet joint capsule (n=1); kinematics were extracted from sagittal plane fluoroscopic data of healthy volunteers (n=10) performing flexion; and average material properties were determined from planar biaxial extension tests of L4–L5 FCLs (n=6). All analyses were performed with the non-linear finite element solver, FEBio. A grid of equally spaced 3×3 nodes on the posterior surface identified regional differences within the strain fields and was used to create comparisons against previously published experimental data. This study was funded by the National Institutes of Health and the authors have no disclosures. RESULTS Inhomogeneous in-plane and through-plane shear deformations were prominent through the middle body of the FCL on both surfaces. Anterior surface deformations were more pronounced because of the small width of the joint space, whereas posterior surface deformations were more diffuse because the larger area increased deformability. We speculate these areas of large deformation may provide this proprioceptive system with an excellent measure of spinal motion. CONCLUSIONS We found that in-plane and through-plane shear deformations are widely present in finite element simulations of a lumbar FCL during flexion. Importantly, we conclude that future studies of the FCL must consider the effects of both shear and tensile deformations.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 94%

Computer simulation of lumbar flexion shows shear of the facet capsular ligament

Claeson

Barocas

2017

The Spine Journal

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“…Once the imaging area had been confirmed and the initial image (REST) had been focused, the volumetric scan commenced, and the data were captured within a few seconds. For the first bend case (BEND 1), the towel forceps were then depressed to a screw angle change ~5° (approximately half the range of maximum L4–L5 motion segment flexion 24 ), the initial image was refocused, and the volumetric scan was captured. This sequence was repeated for BEND 2 at ~10° (maximum L4–L5 motion segment flexion).…”

Section: Methodsmentioning

confidence: 99%

“…The bone-based approach involves imaging vertebral motion and then inferring FCL kinematics. The availability of single-fluoroscopic 24 or dual-fluoroscopic 18 measurements makes this approach attractive, in particular when combined with other imaging modalities and finite-element models, but it is still an indirect measure of FCL motion. The marker-based approach 16 involves suturing markers into the capsule to allow tracking of material points.…”

Section: Introductionmentioning

confidence: 99%

Marker-Free Tracking of Facet Capsule Motion Using Polarization-Sensitive Optical Coherence Tomography

et al. 2015

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We proposed and tested a method by which surface strains of biological tissues can be captured without the use of fiducial markers by instead, utilizing the inherent structure of the tissue. We used polarization-sensitive optical coherence tomography (PS OCT) to obtain volumetric data through the thickness and across a partial surface of the lumbar facet capsular ligament (FCL) during three cases of static bending. Reflectivity and phase retardance were calculated from two polarization channels, and a power spectrum analysis was performed on each a-line to extract the dominant banding frequency (a measure of degree of fiber alignment) through the maximum value of the power spectrum (maximum power). Maximum powers of all a-lines for each case were used to create 2D visualizations, which were subsequently tracked via digital image correlation. In-plane strains were calculated from measured 2D deformations and converted to 3D surface strains by including out-of-plane motion obtained from the PS OCT image. In-plane strains correlated with 3D strains (R2 ≥ 0.95). Using PS OCT for marker-free motion tracking of biological tissues is a promising new technique because it relies on the structural characteristics of the tissue to monitor displacement instead of external fiducial markers.

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“…ROM of 6-13 deg, 1-5 deg, 2.9-11 deg and 2-3 deg in flexion, extension, lateral bending, and torsion, respectively, have been reported [44,45] (Table 2). When the whole spine is moved from a 20 deg extension to a 60 deg flexion posture, L2/3, L3/4, and L4/5 IVDs experience the largest ROM of approximately 9 deg, and L1/2 and L5/S1 experiences 7 deg and 6 deg, respectively [46,47].…”

Section: In Vivo Spine Biomechanicsmentioning

confidence: 99%

Design Requirements for Annulus Fibrosus Repair: Review of Forces, Displacements, and Material Properties of the Intervertebral Disk and a Summary of Candidate Hydrogels for Repair

Long

Torre

Hom

et al. 2016

Journal of Biomechanical Engineering

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There is currently a lack of clinically available solutions to restore functionality to the intervertebral disk (IVD) following herniation injury to the annulus fibrosus (AF). Microdiscectomy is a commonly performed surgical procedure to alleviate pain caused by herniation; however, AF defects remain and can lead to accelerated degeneration and painful conditions. Currently available AF closure techniques do not restore mechanical functionality or promote tissue regeneration, and have risk of reherniation. This review determined quantitative design requirements for AF repair materials and summarized currently available hydrogels capable of meeting these design requirements by using a series of systematic PubMed database searches to yield 1500+ papers that were screened and analyzed for relevance to human lumbar in vivo measurements, motion segment behaviors, and tissue level properties. We propose a testing paradigm involving screening tests as well as more involved in situ and in vivo validation tests to efficiently identify promising biomaterials for AF repair. We suggest that successful materials must have high adhesion strength (∼0.2 MPa), match as many AF material properties as possible (e.g., approximately 1 MPa, 0. 3 MPa, and 30 MPa for compressive, shear, and tensile moduli, respectively), and have high tensile failure strain (∼65%) to advance to in situ and in vivo validation tests. While many biomaterials exist for AF repair, few undergo extensive mechanical characterization. A few hydrogels show promise for AF repair since they can match at least one material property of the AF while also adhering to AF tissue and are capable of easy implantation during surgical procedures to warrant additional optimization and validation.

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Quantification of continuous in vivo flexion–extension kinematics and intervertebral strains

Cited by 13 publications

References 29 publications

Computer simulation of lumbar flexion shows shear of the facet capsular ligament

Computer simulation of lumbar flexion shows shear of the facet capsular ligament

Marker-Free Tracking of Facet Capsule Motion Using Polarization-Sensitive Optical Coherence Tomography

Design Requirements for Annulus Fibrosus Repair: Review of Forces, Displacements, and Material Properties of the Intervertebral Disk and a Summary of Candidate Hydrogels for Repair

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