0326 In-vivo biomechanical evaluation of functional spinal unit in the lumbar spine

Mechanical studies of the Functional Spinal Unit (FSU) in-vitro have shown that the slopes of the load-displacement curves increase with load. This nonlinearity implies that the stiffness of the FSU is not constant over the range of physiologic loads, and that measurements obtained for FSU specimens through the application of individual loads cannot be summed to predict the response of the specimens to combined loads. Both experimental and analytical methods were developed in the present study to better quantify the nonlinear FSU load-displacement response and to calculate the coupled stiffness of FSU specimens at combined states of load reflecting in-vivo conditions. Results referenced to the center of the vertebral body indicate that lumbar FSU specimens are stiffer in flexion than in extension, and that FSU specimens loaded in flexion are stiffer at high loads than at low loads. The importance of combined load testing and a nonlinear interpretation of load-displacement data is demonstrated.

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Three-dimensional distribution of CT attenuation in the lumbar spine pedicle wall

Scientific Reports ◽

10.1038/s41598-020-80676-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Tomoyo Y. Irie ◽

Tohru Irie ◽

Alejandro A. Espinoza Orías ◽

Kazuyuki Segami ◽

Norimasa Iwasaki ◽

...

Keyword(s):

Lumbar Spine ◽

Age Groups ◽

Three Dimensional ◽

Hounsfield Unit ◽

Lateral Wall ◽

Ct Attenuation ◽

Dimensional Distribution ◽

The Mean ◽

Pedicle Wall

AbstractThis study investigated in vivo the three-dimensional distribution of CT attenuation in the lumbar spine pedicle wall measured in Hounsfield Unit (HU). Seventy-five volunteers underwent clinical lumbar spine CT scans. Data was analyzed with custom-written software to determine the regional variation in pedicle wall attenuation values. A cylindrical coordinate system oriented along the pedicle’s long axis was used to calculate the pedicular wall attenuation distribution three-dimensionally and the highest attenuation value was identified. The pedicular cross-section was divided into four quadrants: lateral, medial, cranial, and caudal. The mean HU value for each quadrant was calculated for all lumbar spine levels (L1–5). The pedicle wall attenuation was analyzed by gender, age, spinal levels and anatomical quadrant. The mean HU values of the pedicle wall at L1 and L5 were significantly lower than the values between L2–4 in both genders and in both age groups. Furthermore, the medial quadrant showed higher HU values than the lateral quadrant at all levels and the caudal quadrant showed higher HU values at L1–3 and lower HU values at L4–5 than the cranial quadrant. These findings may explain why there is a higher incidence of pedicle screw breach in the pedicle lateral wall.

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Direct real-time measurement of in vivo forces in the lumbar spine

The Spine Journal ◽

10.1016/j.spinee.2004.06.017 ◽

2005 ◽

Vol 5 (1) ◽

pp. 85-94 ◽

Cited By ~ 41

Author(s):

Eric H. Ledet ◽

Michael P. Tymeson ◽

Darryl J. DiRisio ◽

Benjamin Cohen ◽

Richard L. Uhl

Keyword(s):

Lumbar Spine ◽

Real Time ◽

Time Measurement ◽

Real Time Measurement

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In Vivo Lumbar Spine Kinematics

The Spine Journal ◽

10.1016/j.spinee.2010.07.183 ◽

2010 ◽

Vol 10 (9) ◽

pp. S67-S68

Author(s):

Kirkham B. Wood ◽

Guoan Li ◽

Michael Kozanek ◽

Peter Passias ◽

Shaobai Wang

Keyword(s):

Lumbar Spine ◽

Spine Kinematics

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A technique for quantifying bending moment acting on the lumbar spine in-vivo

Journal of Biomechanics ◽

10.1016/0021-9290(91)90126-8 ◽

1991 ◽

Vol 24 (6) ◽

pp. 480

Author(s):

M.A. Adams ◽

P. Dolan

Keyword(s):

Lumbar Spine ◽

Bending Moment

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Hybrid Rigid-Deformable Model for Prediction of Neighboring Intervertebral Disk Loads During Flexion Movement After Lumbar Interbody Fusion at L3–4 Level

Journal of Biomechanical Engineering ◽

10.1115/1.4035483 ◽

2017 ◽

Vol 139 (3) ◽

Author(s):

Tien Tuan Dao

Keyword(s):

Lumbar Spine ◽

Computational Models ◽

Interbody Fusion ◽

Clinical Decision ◽

Intervertebral Disk ◽

Design Guideline ◽

Spinal Loads ◽

Stress Changes ◽

Stress Behaviors

Knowledge of spinal loads in neighboring disks after interbody fusion plays an important role in the clinical decision of this treatment as well as in the elucidation of its effect. However, controversial findings are still noted in the literature. Moreover, there are no existing models for efficient prediction of intervertebral disk stresses within annulus fibrosus (AF) and nucleus pulposus (NP) regions. In this present study, a new hybrid rigid-deformable modeling workflow was established to quantify the mechanical stress behaviors within AF and NP regions of the L1–2, L2–3, and L4–5 disks after interbody fusion at L3–4 level. The changes in spinal loads were compared with results of the intact model without interbody fusion. The fusion outcomes revealed maximal stress changes (10%) in AF region of L1–2 disk and in NP region of L2–3 disk. The minimal stress change (1%) is noted at the NP region of the L1–2 disk. The validation of simulation outcomes of fused and intact lumbar spine models against those of other computational models and in vivo measurements showed good agreements. Thus, this present study may be used as a novel design guideline for a specific implant and surgical scenario of the lumbar spine disorders.

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