• Neurospine
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• v.15 no.4
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• pp.296-305
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• 2018

Cervical disc arthroplasty (CDA), or total disc replacement, has emerged as an option in the past two decades for the management of 1- and 2-level cervical disc herniation and spondylosis causing radiculopathy, myelopathy, or both. Multiple prospective randomized controlled trials have demonstrated CDA to be as safe and effective as anterior cervical discectomy and fusion, which has been the standard of care for decades. Moreover, CDA successfully preserved segmental mobility in the majority of surgical levels for 5-10 years. Although CDA has been suggested to have long-term efficacy for the reduction of adjacent segment disease in some studies, more data are needed on this topic. Surgery for CDA is more demanding for decompression, because indirect decompression by placement of a tall bone graft is not possible in CDA. The artificial discs should be properly sized, centered, and installed to allow movement of the vertebrae, and are commonly 6 mm high or less in most patients. The key to successful CDA surgery includes strict patient selection, generous decompression of the neural elements, accurate sizing of the device, and appropriately centered implant placement.

• Coupled systems mechanics
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• v.8 no.3
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• pp.273-287
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• 2019

Elastoplastic analysis of an annular disc, being fully constrained on its outer rim and interacting with a purely elastic inclusion perfectly bonded with its inner rim, is conducted to study its plastic deformation and residual stress under thermal cycles. The system is termed the composite disc. Quasi-static plane-strain deformation is assumed, and the von Mises yield criterion with or without the Ludwik hardening rule is adopted in our finite element calculations. Effects of multiple material properties simultaneously being temperature dependent on the plastic behavior of the composite disc are considered. Residual stress is analyzed from a complete loading and unloading cycle. Results are discussed for various inclusion radii. It is found that when temperature dependent material properties are considered, the maximum residual stress may be greater than the maximum stress inside the disc at the temperature-loaded state due to lower temperature having larger yield stress. Temperature independent material properties overestimate stresses inside materials, as well as the elastic irreversible temperature and plastic collapse temperature.

• Journal of Oral Medicine and Pain
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• v.23 no.1
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• pp.21-36
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• 1998

The purpose of this study was analyse the mandibular movements in patients with internal derangement of the temporomandibular joint according to diagnostic subgroups. The author classified patients with internal derangement of the temporomandibular joint into 4 diagnostic subgroups by means of the magnet resonance imagings, and evaluated the clinical signs and the mandibular movements with Mandibular Kinesiograph(MKG) in each subgroups. The mandibular movements, measured in this study, were the types of movement in frontal and sagittal plane, velocities in opening and closing movement, and the opening and closing movement, and the opening and closing velocity pattern. The data were compared between the 5 groups including the normal group. The results were as follows : 1. Pain was more frequently observed in the anterior disc displacement without reduction group than in the anterior disc displacement with reduction group. Sound of joint was more frequently observed in the anterior disc displacement with reduction group, and limitation of mandibular opening movement was more frequently observed in the anterior disc displacement without reduction group. Duration of the anterior disc displacement without reduction group was significantly short compared to that of the anterior disc displacement with reduction group, and duration of the unilateral anterior disc displacement without reduction group was shortest in the experimental group. The frequency of Angle's classifications had not significant correlations between the experimental groups. 2. Active and passive range of the opening movement, maximum protrusive movement, maximum lateral movement toward left side were significantly decreased in the experimental groups compared to the control group, but there was no significant difference in the range of the maximum lateral movement toward right side between the control and experiment groups. In unilateral anterior disc displacement without reduction group, the range of maximum lateral movement toward unaffected side was no significant difference in the range of the maximum lateral movement between toward affected side and toward unaffected side. 3. Maximum opening velocity, maximum closing velocity, average opening velocity, average closing velocity and maximum velocity of terminal tooth contact were significantly decreased in the experimental groups compared to control group. There was no significant difference in maximum opening velocity and maximum velocity of Terminal tooth contact between the subgroups of the experimental group each other, but there was significant difference in maximum closing velocity, average opening velocity and average closing velocity between the subgroups each other. 4. In the frontal plane of the MKG, the frequency of complex deviation type(F-2)pattern was significantly increased in the anterior disc displacement with out reduction group compared to the anterior disc displacement with reduction group and the control group. In the sagittal plane, the frequency of coincident type(S-1)was decreased in the same group. 5. In the maximum opening velocity pattern, the frequency of no-peak type (OV-3)in the unilateral anterior disc displacement with reduction group was significantly increased compared to the control group. The frequency of 1-peak type (OV-1) and 2-peak type (OV-2) was decreased in the anterior disc displacement with out reduction group, but the frequency of no-peak type (OV-3)was increased in the same group. In the maximum closing velocity pattern, the frequency of no-peak type (CV-3) was significantly increased in the anterior disc displacement without reduction group. Compared to the anterior disc displacement with reduction group and the control group. The frequency of 1-peak type (CV-1) and 2-peak type (CV-2) in the anterior disc displacement with reduction group was decreased than that in the control group.

• Journal of Acupuncture Research
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• v.18 no.4
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• pp.1-12
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• 2001

Study design : A retrospective study of lumbar disc herniations using results of follow-up computed tomographic scan examinations. Objective : Lumbar disc herniations is one of the cause low back pain and lower extremity pain. To clarify the lumbar disc herniations morphological changes over time(mean 5.3 years) in order to establish a strategy for treatment. Methods : Sixteen patients with lumbar disc herniations who underwent follow-up computed tomographic scan examinations were studied. The changes over time in herniated disc size(herniation ratio) were evaluated using this scan technique. The initial computed tomographic scan allowed classification of the herniations according to herniation ratio: small, medium and large. Results : Comparison with follow-up computed tomographic scans showed that of the 16 patients, in 14 patients(88%), the herniation ratio(HR) was decreased and among them, 8 patients had complet resolution of herniated disc. In 2 patients with small herniations, the HR of one case was increased, the other was decreased. In 8 patients with medium herniations, the HR of one case had no change, the others was decreased. In 6 patients with large herniation, the HR of all patients was decreased. Interestingly, 4 of the 16 patients showed calcification change of herniated disc. Conclusion : There is no doubt that herniated disc size is decreased over time. The largest herniations were those which had the greatest tendency to decrease in size. But in some cases, the HR was increased, or calcification change was showed.

• Journal of radiological science and technology
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• v.30 no.4
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• pp.407-417
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• 2007

The purpose of this study is to determine whether change of the lumbar intervertebral disc diameters and size is a risk factor for development of lumbar disc lesion and this changes are associated with aging. The L4-5 and L5-S1 intervertebral disc diameters and size were measured in 50 normal subjects and 50 low back pain patients in the age range $20{\sim}60$ by MRI. The data were analysed with independent t-test to differentiation between normal subjects and low back patients. We also analysed with one-way ANOVA, Pearson correlation and simple linear regression to differentiate between different age ranges. This study has shown that older subjects of both normal and low back pain patients have significantly larger transverse diameters and sizes of the L4-5 and L5-S1 intervertebral disc, compared with those of younger subjects. In addition, low back pain patients's disc sizes were larger than normal subjects but there was statistically no significant difference. The measurement of the intervertebral disc size can be considered as a clinically useful method for diagnosis of the low back pain and aging of the intervertebral disc. However, further study should be conducted to establish normal value of intervertebral disc size on large number of subjects.

• Journal of Korean Tunnelling and Underground Space Association
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• v.17 no.4
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• pp.473-485
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• 2015

The problems for non-rotating of a disc cutter proceed from the faults in inner parts of the disc cutter such as the leak of hydraulic fluid, the intrusion of tunnel mucks and water, overloading, overheating, poor assembly and substandard material. The rotating of a disc cutter is an indicator to show that the inner parts of disc cutter is operable, although the rotational torque depends on the extent of the damage. Therefore, the key in the problems for non-rotating of disc cutter is to maintain that the tapered roller bearings are working properly. This study aims to investigate the inner parts disassembled from disc cutters applied to the field tests in order to help decision for reuse of the disc cutters. As results, surface finishing to remove the scratch on the load zone of the hubs is needed, with the intent to reuse a hub. And the investigation of lapping surface by optical microscope of floating seals and the contamination test of oil need to be performed for reuse of a disc cutter. Especially, the analysis results show that the floating seals play a key role in the normal operation of bearings. There is nothing significant to report in the rest parts such as bearing, shaft, seal retainers.

• Tunnel and Underground Space
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• v.21 no.3
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• pp.151-163
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• 2011

The LCM test is one of the most powerful and reliable methods for designing the disc cutter and for predicting the TBM (Tunnel Boring Machine) performance. It has an advantage to predict the actual load on disc cutter from the laboratory test on the real-size large rock samples, however, it also has a disadvantage to transport and/or prepare the large rock samples and to need an extra cost for experiment. Moreover it is not easy to execute the test for jointed rock mass, and sometimes the design model estimated from the test can not be applied to the real design of disc cutter. In order to break this critical point, lots of numerical studies have been performed. PFC2D can simulate crack propagation and rock fragmentation effectively, because it is useful in particle flow analysis. Consequently, in this study, the PFC2D has been adopted for numerical analysis on cutting power of disc cutter according to the different angle of joint, the different direction of joint, and the different space of joint with jointed rock mass models. From the numerical analyses, it was concluded that the bigger cutting power of disc cutter was needed for reverse cutting direction to joint rather than for forward direction, and the cutting power of disc cutter was increased with decreasing the dip angle of joint and decreasing the space of joints in reverse cutting direction. The more precise numerical model for disc cutter can be developed from comparison between the numerical results and LCM test results, and the resonable guideline is expected for prediction of TBM performance and disc cutter.

• The Journal of Churna Manual Medicine for Spine and Nerves
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• v.10 no.1
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• pp.63-74
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• 2015

Objectives : This study is planned to classify correlation between thoracic kyphosis angle and prevalence of cervical intervertebral disc. Methods : We Measured the thoracic kyphosis angel of the 110 men and 179 women patients with neck pain in 00 Korean Medicine Hospital. We use Cobb's angle method and Thoracic cage dimension method for measuring the thoracic kyphosis. And We use Magentic Resonance Imaging(MRI) for classifying the patient who has cervical intervertebral disc or not. Results : 1. There was statistical difference on the thoracic cage dimension with gender(P<0.001), while there was no statistical difference on Cobb's angle with gender(P=0.882). 2. Age and thoracic cage dimension(r=0.383) is statistically more correlative than age and cobb's angle(r=-0.59). Conclusions : 1. Thoracic cage dimension and gender, Thoracic cage dimension and age were statistically concerned on patient who has neck pain, while Cobb's angle had no statistical correlation with age and gender. 2. There was no statistical difference on the Cobb's angle and Thoracic cage Dimension between patient who has one or more cervical disc herniation(Protrusion disc, Extrusion disc) segment and patient who didn't have cervical disc herniation(Protrusion disc, Extrusion disc) segment.

• Journal of the Korea Convergence Society
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• v.12 no.3
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• pp.107-114
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• 2021

The purpose of this study is to investigate whether there is a difference in the effect of learning flow and teaching presence according to the lecturer's appearance and students' behavioral patterns in video learning. For this experiment, 183 freshmen from Xingtai University in China were selected as subjects. After being classified according to DISC, students were assigned to study the lecture videos with the appearance of the lecturer and the video without the appearance of the lecturer. After testing the level of their learning flow and teaching presence, the differences between groups were analyzed. According to the results of the analysis, the learning flow and teaching presence of groups who learned the videos in which the lecturer appeared were significantly higher than the groups who learned the videos without the appearance of the lecturer. Second, the effects of whether the lecturer appears or not according to DISC on learning flow were significant. However, the effects of DISC, and the interactive effect of DISC and the lecturer appearance were found to have no significant interactive effect on learning flow. Third, the effects of whether the lecturer appears or not according to DISC on teaching presence were significant, and the effects of DISC on teaching presence were not significant, but the interactive effect of lecturer appearance and DISC was significant. These findings suggest that lecture videos with the appearance of the lecturer generally have better effect. In particular, in order to enhance teaching presence, it is effective to decide whether the lecturer appears or not by considering its interactive effects with learners' DISC.

• Imaging Science in Dentistry
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• v.36 no.1
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• pp.41-48
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• 2006

Purpose : To evaluate the reliability and clinical usefulness of ultrasonography in the temporomandibular joint (TMJ). Materials and Methods : Parasagittal and paracoronal 1.5 T MR images and 7.5 MHz ultrasonographs of 40 TMJs in 20 asymptomatic volunteers were obtained. Disc position using MR imaging was evaluated and the distance between the lateral surface of mandibular condyle and the articular capsule using MR image and ultrasonograph of 27 TMJs with normal disc position was measured and compared. Intraobserver and interobserver measurements reliability was evaluated by using interclass correlation coefficients (ICC) and measurement error. Also, the distance measured on ultrasonographs was compared, according to mouth position and disc postion. Results : The normal disc position was found in 27 of 40 asymptomatic joints. At the intraobserver reliability of measurement, ICC at the closed and open mouth position were 0.89 and 0.91. The measurement error was 0.4% and 0.5%. At the interobserver reliability, ICC at the closed and open mouth position were 0.92 and 0.81. The measurement error was 0.4% and 0.7%. At the TMJ with normal disc position, the distances between the lateral surface of mandibular condyle and the articular capsule measured on MR images and ultrasonographs were $2.0{\pm}0.7mm,\;1.8{\pm}0.5mm$, respectively (p<0.05). On the ultrasonographs, the distances at open mouth position were $1.2{\pm}0.5mm$ (p<0.05). At the TMJ with medially displaced disc, the distances at the closed and open mouth position were $1.3{\pm}0.3\;mm\;and\;0.9{\pm}0.2\;mm$ (p<0.05). Conclusion : The results suggest ultrasonography of TMJ is a reliable imaging technique for assessment of normal disc position.