• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.7
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• pp.637-644
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• 2009

We have analyzed the biomechanical characteristics of cervical spine after total disc replacement using finite element analysis. A finite element model of C2-C7 spinal motion segment was developed and validated by other experimental studies. Two types of artificial discs, semi-constraint and un-constraint, were inserted at C6-C7 segments. Inferior plane of C7 vertebra was fixed and 1Nm of moment were applied on superior plane of C2 vertebra with 50N of compressive load along follower load direction. Mobility of the cervical spine in which each artificial disc inserted was higher than that of intact one in all loading conditions. Also, high mobility at the surgical level after total disc replacement could lead higher facet joint force and ligaments axial stresses. The results of present study could be used to evaluate surgical option and validate the biomechanical characteristics of the implant in total disc replacement in cervical spine.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.1
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• pp.29-35
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• 2012

The treatments for spinal canal stenosis are radicular cyst removal, spine fusion, and implantation of an artificial intervertebral disc. Artificial intervertebral discs have been most widely used since the mid-2000s. The study of artificial intervertebral discs has been focused on the analysis of the axial rotation, lateral bending, the degrees of freedom of the disc, and flexion-extension of the vertebral body. The issue of fatigue failure years after the surgery has arisen as a new problem. Hence, study of artificial intervertebral discs must be focused on the fatigue failure properties and increased durability of the sliding core. A finite element model based on an in the artificial intervertebral disc (SB Charit$\acute{e}$ III) was produced, and the influence of the radius of curvature and the change in the coefficient of friction of the sliding core on the von-Mises stress and contact pressure was evaluated. Based on the results, new artificial intervertebral disc models (Models-I, -II, and -III) were proposed, and the fatigue failure behavior of the sliding core after a certain period of time was compared with the results for SB Charit$\acute{e}$ III.

• Korean Journal of Computational Design and Engineering
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• v.13 no.1
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• pp.58-66
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• 2008

The artificial discs have recently used to preserve the motion of the treated segment in lumbar spine surgery. However, there have been lack of biomechanical information of the artificial discs to explain current clinical controversies such as long-term results of implant wear and excessive facet contact forces. In this study, we investigated the biomechanical effects of three artificial implants on the lumbar spinal segments by finite element analysis. The finite element model of intact lumbar spine(L1-S) was developed and the three implants were inserted in L4-L5 segment of the spine model. 5 Nm of flexion and extension moments were applied on the superior plate of L1 with 400 N of compressive load. Excessive motions and high facet contact forces at the surgical level were generated in the all three implanted models. In the flexion, the peak von-Mises stresses in the semi-constrained type implant was higher than those in the un-constrained type implant which would cause wear on the polyethylene core. The results of the study would provide a biomechanical guideline for selecting optimal surgical approach or evaluating the current design of the implants, or developing a new implant.

• Journal of Chest Surgery
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• v.42 no.6
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• pp.719-724
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• 2009

Background: As the patients who undergo heart transplantation have achieved better survival in recent years, growing number of recipients are at a risk for experiencing surgical complications in addition to rejection and infection. In this paper, we report on our experience with the surgical complications that occurred in heart transplant recipients. Material and Method: From April 1994 to September 2003, 37 heart transplantations were performed at our center by a single surgeon. The indications for transplantation were dilated cardiomyopathy, ischemic cardiomyopathy, valvular cardiomyopathy and familial hypertrophic cardiomyopathy. Result: Twenty postoperative complications required surgeries in 15 patients (41%). The types of operations required were; redo-sternotomy for bleeding (5), pericardiostomy for effusion (4), implantation of a permanent pacemaker (1), right lower lobe lobectomy for aspergilloma (1), removal of urinary stone (1), cholecystectomy for gall bladder stone (1), drainage of a perianal abscess (1), paranasal sinus drainage (1), total hip replacement (1), partial gingivectomy due to gingival hypertrophy (1), urethrostomy (1), herniated intervertebral disc operation (1) and total hysterectomy for myoma uteri (1). The locations of the complications were mediastinal in 10 (27%) cases and extramediastihalin 10 (27%) cases. Conclusion: The relatively high incidence of extrathoracic complications associated with heart transplantation emphasizes the importance of a multidisciplinary approach to the improve long-term survival when managing those complex patients.