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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/3

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Department: search.filters.department.Department of Mechanical EngineeringSubject: search.filters.subject.Clinical neurology

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    Determination of the biomechanical effect of an interspinous process device on implanted and adjacent lumbar spinal segments using a hybrid testing protocol: a finite-element study
    (Amer Assoc Neurological Surgeons, 2015) N/A; N/A; N/A; N/A; Department of Mechanical Engineering; Erbulut, Deniz Ufuk; Zafarparandeh, Iman; Hassan, Chaudhry Raza; Lazoğlu, İsmail; Özer, Ali Fahir; Researcher; PhD Student; Master Student; Faculty Member; Faculty Member; Department of Mechanical Engineering; School of Medicine; Graduate School of Sciences and Engineering; Graduate School of Sciences and Engineering; College of Engineering; 37661; N/A; N/A; 179391; 1022
    OBJECT The authors evaluated the biomechanical effects of an interspinous process (ISP) device on kinematics and load sharing at the implanted and adjacent segments. METHODS A 3D finite-element (FE) model of the lumbar spine (L1-5) was developed and validated through comparison with published in vitro study data. Specifically, validation was achieved by a flexible (load-control) approach in 3 main planes under a pure moment of 10 Nm and a compressive follower load of 400 N. The ISP device was inserted between the L-3 and L-4 processes. Intact and implanted cases were simulated using the hybrid protocol in all motion directions. The resultant motion, facet load, and intradiscal pressure after implantation were investigated at the index and adjacent levels. In addition, stress at the bone-implant interface was predicted. RESULTS The hybrid approach, shown to be appropriate for adjacent-level investigations, predicted that the ISP device would decrease the range of motion, facet load, and intradiscal pressure at the index level relative to the corresponding values for the intact spine in extension. Specifically, the intradiscal pressure induced after implantation at adjacent segments increased by 39.7% and by 6.6% at L2-3 and L4-5, respectively. Similarly, facet loads at adjacent segments after implantation increased up to 60% relative to the loads in the intact case. Further, the stress at the bone-implant interface increased significantly. The influence of the ISP device on load sharing parameters in motion directions other than extension was negligible. CONCLUSIONS Although ISP devices apply a distraction force on the processes and prevent further extension of the index segment, their implantation may cause changes in biomechanical parameters such as facet load, intradiscal pressure, and range of motion at adjacent levels in extension.
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    Comparison of the morphologic and mechanical features of human cranial dura and other graft materials used for duraplasty
    (Elsevier Science Inc, 2022) Ozkan, Mazhar; N/A; N/A; N/A; N/A; N/A; Department of Mechanical Engineering; Çavdar, Safiye; Sürücü, Hüseyin Selçuk; Malik, Anjum Naeem; Tanış, Özgül; Lazoğlu, İsmail; Faculty Member; Faculty Member; PhD Student; PhD Student; Undergraduate Student; Faculty Member; Department of Mechanical Engineering; School of Medicine; School of Medicine; Graduate School of Health Sciences; Graduate School of Sciences and Engineering; School of Medicine; College of Engineering; 1995; 21780; N/A; N/A; N/A; 179391
    Objective: This study aimed to compare the thickness and mechanical properties of the frontal; parietal; temporal; occipital human dura; autogenous grafts (facia lata, temporal fascia, galea aponeurotica); and artificial dura. Methods: Sagittal and transverse dura samples were obtained from standard regions of the cranial dura from 30 autopsies for histologic and mechanical property measurements. Identical measurements were made for the autogenous grafts artificial dura, and the results were statistically analyzed. Results: The thickness of the temporal (0.35 +/- 0.11 mm), parietal (0.44 +/- 0.13 mm), frontal (0.38 +/- 0.12 mm), and occipital (0.46 +/- 0.18 mm) dura showed regional variations. The parietal and occipital dura were significantly thicker than the temporal dura. The occipital dura was considerably thicker than the frontal dura. The frontal and temporal dura of males were significantly thicker than females. The sagittal maximum tensile force measurements were significantly greater than transverse, for the frontal, temporal, and occipital dura. The stiffness measurements in sagittal direction were greater than the measurements in transverse direction for the frontal dura. The mechanical properties and thickness of the autogenous and artificial dura were not similar to the human dura. Consclusions: The thickness and mechanical properties of the regional cranial dura should be taken into consideration for a better cure and fewer complications. The mechanical properties of sagittal and transverse dura should be kept in mind for the preference of dura material. The present study's data can pave the way to produce artificial regional dura by mimicking the thickness and mechanical properties of the human dura.