Multiscale Mechanical Changes to the Collagenous Structure in the Annulus Fibrosus from Adult Degenerative Disc Disease and Adult Spine Deformity Surgical Patients
Date
2023-06
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Abstract
The annulus fibrosus in patients with degenerative disc disease (degen) and adult spinal deformities, including degenerative spondylolisthesis (dSpondy), isthmic spondylolisthesis (iSpondy), degenerative scoliosis (dScoli), and adolescent idiopathic scoliosis (AIS), often exhibit severely degenerated discs at the time of surgery. These conditions are accompanied by mechanical and structural changes in the annulus fibrosus, which can cause significant pain and affect mobility. In many cases, the patients require surgical intervention. The overarching hypothesis was that surgical patients have mechanical and structural integrity of the annulus fibrosus compared to normal patients. The objective of the study was to quantify the interlamellar mechanics, circumferential tensile mechanics, and collagen damage in samples from these patients. Interlamellar mechanical properties (Peel Stiffness, Peel Strength, and Peel Toughness) were decreased in the surgical patients compared to the normal patients suggesting a loss of integrity of the collagenous interlamellar matrix in surgical patients. Moderate to strong positive correlations between interlamellar properties and Pfirrmann Grade were observed. Circumferential tensile properties (Rate of Change of Tangential Modulus, Linear Elastic Modulus, Yield Stress, and Ultimate Tensile Stress) were decreased in the surgical patients compared to the normal patients suggesting a loss of collagen's mechanical integrity in the circumferential direction. The collagen hybridizing peptide indicated greater average mean fluorescence intensity and average percent positive ROI area in the surgical patients compared to the normal patients suggesting a loss of structural integrity of collagen. In conclusion, the present study demonstrated that compared to normal patients, surgical patients experienced a greater loss of collagen's structural and mechanical integrity in the annulus fibrosus at molecular and tissue scales.
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Keywords
Annulus Fibrosus, Degenerative Disc Disease, Spine Deformities, Collagen, Biomechanics
Citation
Dhiman, M. (2023). Multiscale mechanical changes to the collagenous structure in the annulus fibrosus from adult degenerative disc disease and adult spine deformity surgical patients (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.