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Biomechanical Evaluation of Vertebral Augmentation to Compare Biocure Cement with PMMA

Mhatre, Devdatt

Abstract Details

2011, Master of Science in Bioengineering, University of Toledo, Bioengineering.
A vertebral compression fracture occurs when the vertebral body of the spine is collapsed due to trauma. In certain circumstances and population groups such as elderly people or in individuals with osteoporotic disorder and cancer, vertebral compression fracture may occur with a minimal compressive force. The most common location of such fractures is in the anterior column of the thoracolumbar region of the spine forming an anterior wedge fracture. Vertebral augmentation is a minimally invasive surgical procedure of cement injection in a collapsed vertebra used to stabilize and reinforce such compression fracture and has proven to be effective in relieving pain compared to conservative treatments. This study was focused on the adjacent level fractures caused due to possible mismatch between augmented osteoporotic bone and high modulus cement resulting in inappropriate load sharing. Biocompliant Biocure bone cement with modulus matching trabecular bone was evaluated and compared with commercially available high modulus PMMA cement. A three dimensional, non-linear osteoporotic T12-L3 finite element model was developed and validated for this study. The finite element mesh of the L1 vertebral body was modified to form oval concentric cylinders in order to simulate a vertebral augmentation in the center of the vertebral body. A compression fracture was simulated in the L1 vertebral body by using a modulus reduction criterion. Vertebral augmentation was then simulated at two distinct cement stiffness values of Biocure and PMMA bone cement to compare with osteoporotic model. The load control protocol was used to evaluate motion of the spine and parameters like Von Mises stresses, intradiscal pressure, facet loads, and stress contour plots were analyzed for each model. The load transferred through the facets decreased and the corresponding endplate stresses increased with increase in cement stiffness. The study also indicated that when a particular level was treated, a higher effect on the stresses was observed at an adjacent upper level than an adjacent lower level. Trends were most evident in the compression loading configuration and at the largest cement volume. Cadaveric kinematic experiments were carried out to investigate the motion in the spinal segment as well as to analyze the increase in intradiscal pressure at adjacent levels when loaded and augmented with Biocure and PMMA cement. Fatigue performance was studied by mechanically loading the augmented vertebral segment (with Biocure and PMMA) for 1.25 million cycles. This was followed by computer tomography scan evaluation for potential endplate cracks. Additionally, destructive sectioning of augmented vertebrae was undertaken for possible cement cracks due to fatigue loading. The results of this study provide an insight on the mechanics of vertebral augmentation with respect to variation in cement properties. Load sharing with Biocure bone cement augmentation was similar to intact compared to PMMA. Fatigue analysis helped in evaluating the long term sustainability of Biocure cement when augmented in the osteoporotic bone. This suggests that cement stiffness lower than the commercially available (high modulus) bone cement may be beneficial from biomechanical perspective.
Vijay Goel, PhD (Committee Chair)
Scott Molitor, PhD (Committee Member)
Ahmad Faizan, PhD (Committee Member)

Recommended Citations

Citations

  • Mhatre, D. (2011). Biomechanical Evaluation of Vertebral Augmentation to Compare Biocure Cement with PMMA [Master's thesis, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1309390838

    APA Style (7th edition)

  • Mhatre, Devdatt. Biomechanical Evaluation of Vertebral Augmentation to Compare Biocure Cement with PMMA. 2011. University of Toledo, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1309390838.

    MLA Style (8th edition)

  • Mhatre, Devdatt. "Biomechanical Evaluation of Vertebral Augmentation to Compare Biocure Cement with PMMA." Master's thesis, University of Toledo, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1309390838

    Chicago Manual of Style (17th edition)