Atefeh Rezaei rad; Mohammad Nikkhoo; Siamak Khorrami mehr
Abstract
Abstract Background & Aim: Cervical spine injuries often cause disability and adversely affect the overall performance and life quality of people. Therefore, recognition of the damage and dysfunction of the cervical spine and biomechanical response to external stimuli is of paramount importance. ...
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Abstract Background & Aim: Cervical spine injuries often cause disability and adversely affect the overall performance and life quality of people. Therefore, recognition of the damage and dysfunction of the cervical spine and biomechanical response to external stimuli is of paramount importance. Accordingly, finite element (FE) modeling can help researchers to access the internal stresses and strains in the bones, ligaments and soft tissues. The present study aimed to compare the biomechanical behavior of the cervical spine before and after trauma.Materials and Methods: In this study, we developed a healthy model along with two different traumatic injuries of the cervical spine modeled by the FE method. The results of the models were compared under static loading. Results: We estimated and evaluated three parameters of intervertebral rotation, facet joint force and intra-disc pressure by considering follower load. The results of the mentioned parameters were evaluated in the two traumatic injury models and the healthy model in flexion, extension, side bending and axial rotation movements at all levels.Conclusion: According to the results, trauma modeling caused changes in the biomechanical behavior of the model, including decreased range of motion in the traumatic injury models, reduced intra-disc pressure and increased facet joint force. This structural disruption in this complex system caused abnormal behavior in various movements. According to the results, the lack of improvement of the biomechanical behavior of the model would cause spinal instability and could increase the probability of injuries in different segments of the lower cervical spine in the long term.
Spine
Seyyed Mohammad Moein Fatemi; Mohammad Nikkhoo; Mostafa Rostami; Chih-Hsiu Cheng
Abstract
In recent years, spinal fusion surgery has become one of the most common treatments for spinal cord injuries, while the interbody cages, which replace the damaged interbody discs in the surgeries, have undergone extensive changes in design and material. These changes are quite visible, ranging from plain ...
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In recent years, spinal fusion surgery has become one of the most common treatments for spinal cord injuries, while the interbody cages, which replace the damaged interbody discs in the surgeries, have undergone extensive changes in design and material. These changes are quite visible, ranging from plain titanium cages made using the conventional manufacturing methods to customized porous titanium cages, which are made using additive manufacturing technology, or titanium-coated polymer cages. Among all the materials used in manufacturing the interbody cages, PolyEther Ether Ketone (PEEK) and titanium are the most common ones. Each of these two has its own advantages and disadvantages. Several studies have compared these two materials, mostly based on the two characteristics of subsidence and fusion rates. The present study performed a comprehensive review of the published clinical studies comparing the titanium and PEEK cages in order to make a comprehensive evaluation of these two. According to the reviewed studies, both materials had relatively similar results in subsidence rate, with no significant difference. However, it was shown that the titanium cages had a better fusion rate and subsequently were more likely to be successful in the clinical settings than the PEEK cages.
Ehsan GhobadiHa; Mohammad Nikkhoo; Sadegh NaserKhaki
Abstract
Background: About 80% of the population will experience back pain in their lifetime; however, although many patients have low back pain associated with disc degeneration, the exact course of degeneration is still unclear. The disc degeneration disorder has affected one-third of the world's young population. ...
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Background: About 80% of the population will experience back pain in their lifetime; however, although many patients have low back pain associated with disc degeneration, the exact course of degeneration is still unclear. The disc degeneration disorder has affected one-third of the world's young population. During degeneration, the disc undergoes morphological and biochemical changes, which in turn alter the tissue hydration, permeability, and ultimately the load-bearing capacity of the disc. Therefore, the finite element model, designed to study the relationship between frequent loading and disk degeneration, must be able to analyze the complex loading in the in-vivo conditions. The aim of this study was to construct and update models of finite element components with the prolastic properties so that different quasi-static loads could be investigated by presenting a personalized model in different individuals and applied in clinical studies to simulate the daily biomechanical behavior for accurate diagnosis and treatment.Method: This study simulated three different modes of finite element modeling, including axial symmetry method, parametric model and precision model with poroelastic mechanical properties and its results were compared with experimental in-vivo experiments.Results: To validate the constructed models, the results of three different quasi-static creep experiments were performed, including short-term creep, long-term creep and creep under regular daily activities, the results of which predicted changes. The results predicted height changes, axial displacement of the spine and the intradiscal pressure of the nucleus.Conclusion: All the proposed results indicated that the models presented in quasi-statistic behavior predicted acceptable results and have sufficient validity to be examined in other quasi-statistic experiments. Therefore, it is possible to take a step forward in examining the results of clinical activities in determining the process of intervertebral disc degeneration.
