• Journal of Korean Neurosurgical Society
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• 제62권1호
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• pp.83-89
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• 2019

Objective : This study is a retrospective cost-benefit analysis of cervical anterior interbody fusion and cervical artificial disc replacement, which are the main surgical methods to treat degenerative cervical disc disease. Methods : We analyzed 156 patients who underwent anterior cervical disc fusion and cervical artificial disc replacement from January 1, 2008 to December 31, 2009, diagnosed with degenerative cervical disc disorder. In this study, the costs and benefits were analyzed by using quality adjusted life year (QALY) as the outcome index for patients undergoing surgery, and a Markov model was used for the analysis. Only direct medical costs were included in the analysis; indirect medical costs were excluded. Data were analyzed with TreeAge Pro $2015^{TM}$ (TreeAge Software, Inc, Williamstown, MA, USA). Results : Patients who underwent cervical anterior fusion had a total cost of KRW 2501807/USD 2357 over 5 years and obtained a utility of 3.72 QALY. Patients who underwent cervical artificial disc replacement received 4.18 QALY for a total of KRW 3685949/USD 3473 over 5 years. The cumulative cost-effectiveness ratio of cervical spine replacement surgery was KRW 2549511/QALY (USD 2402/QALY), which was lower than the general Korean payment standard. Conclusion : Both cervical anterior fusion and cervical artificial disc replacement are cost-effective treatments for patients with degenerative cervical disc disease. Cervical artificial disc replacement may be an effective alternative to obtain more benefits.

• Geomechanics and Engineering
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• 제38권6호
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• pp.633-645
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• 2024

Disc cutters, used as excavation tools for rocks in a Tunnel Boring Machine (TBM), naturally undergo wear during the tunneling process, involving crushing and cutting through the ground, leading to various wear types. When disc cutters reach their wear limits, they must be replaced at the appropriate time to ensure efficient excavation. General disc cutter life prediction models are typically used during the design phase to predict the total required quantity and replacement locations for construction. However, disc cutters are replaced more frequently during tunneling than initially planned. Unpredictable disc cutter replacements can easily diminish tunneling efficiency, and abnormal wear is a common cause during tunneling in complex ground conditions. This study aims to overcome the limitations of existing disc cutter life prediction models by utilizing machine data generated during tunneling to predict disc cutter wear patterns and determine the need for replacements in real-time. Artificial intelligence classification algorithms, including K-nearest Neighbors (KNN), Support Vector Machine (SVM), Decision Tree (DT), and Stacking, are employed to assess the need for disc cutter replacement. Binary classification models are developed to predict which disc cutters require replacement, while multi-class classification models are fine-tuned to identify three categories: no replacement required, replacement due to normal wear, and replacement due to abnormal wear during tunneling. The performance of these models is thoroughly assessed, demonstrating that the proposed approach effectively manages disc cutter wear and replacements in shield TBM tunnel projects.

• The Journal of Korean Physical Therapy
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• 제25권6호
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• pp.417-421
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• 2013

Purpose: This study was to identify the effect of cervical stabilization exercise on pain and structure in patients with cervical artificial disc replacement. Methods: Forty-four individuals with cervical artificial disc replacement volunteered to participate from FEB 2012 to MAR 2013 in this study. They were allocated to either Experimental Group (EG) or Control Group (CG), with 22 subjects in each group. Subjects from the EG performed cervical stabilization exercise program and subjects from the CG performed isometric exercise program. Assessment tools were made with the Visual Analogue Scale (VAS), Neck Disability Index (NDI), and Cervical Lordosis Angle (CLA). Results: In this study, in within-group and between-group comparison, the EG and CG showed significant differences in all parameters(p<0.05). But EG showed more improvement than CG at all parameters. Conclusion: These findings suggest that cervical stabilization exercise may be favorably used to improve VAS, NDI and CLA in patients with cervical artificial disc replacement. Further studies with larger sample and long-term follow-up period need to generalize the results of this study.

• 대한기계학회논문집A
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• 제33권7호
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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.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.515-516
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• 2006

The goal of total disc replacement is to restore pain-free mobility to a diseased functional spinal unit, by replacing the degenerated disc with a mobile bearing prosthesis. SB Charite III is named commercial product as the Artificial Intervertebral Disc (AID). SB Charite III consists of sliding core and endplate made by Ultra-high Molecular Weight Polyethylene (UHMWPE) and cobalt chrome alloy, respectively. To evaluate the effect of von-Mises stress in AID, and three-dimensional finite element model of AID analysis was preformed for four different loading types of sliding core. Consequently, endplate was compared with a compressive preload at 400N and flexion moment at $3{\sim}9Nm4. Therefore, this research has obtained result that von-Mises stress of sliding core in AID disc by radius curvature.

• 한국CDE학회논문집
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• 제13권1호
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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.

• Neurospine
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• 제15권4호
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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.

• Journal of Korean Neurosurgical Society
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• 제61권4호
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• pp.530-536
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• 2018

We present two cases of unexpected postoperative intractable cervicalgia due to over-sized implant insertion during simple anterior cervical decompression and fusion (ACDF) or artificial disc replacement (ADR). These patients experienced severe cervicalgia mostly related to their neck motion even after standard cervical operations. In both cases, the restored disc heights after the operations were prominently greater than the preoperative disc heights. The patients had not responded to any of the conservative treatments, and unloading of these excessively distracted segments through ultimate revision surgery led to dramatic pain relief. This report emphasizes the increase in distractional forces that takes place after a standard ACDF or ADR, as well as the importance of a proper sized implant. It also includes the reviews of other biomechanical or clinical reports dealing with this issue, thereby cautioning the surgeons not to disregard these factors, which might have an adverse effect in patients with cervicalgia even after radiographically successful cervical procedures.

• 대한의용생체공학회:의공학회지
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• 제31권1호
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• pp.56-66
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• 2010

The various total replacement artificial discs have developed because spinal fusion has shown a lesser mobility of an operated segment and an accelerated degeneration at adjacent discs. But almost artificial discs have not yet been reached on the substitute surgery of fusion because many problems such as those clinical success rates were not more than them of fusion have not solved. In this paper, vertically inserted assemble-screw fixture in vertebrae was proposed to improve the fixed capability of artificial disc. And also, to evaluate the design suitability of newly designed screw-type, including fixtures of commercial discs such as wedge and plate type, the 1/4 finite element model with a vertebra and various implanted fixtures were generated, and next, 3 bending motions such as flexion, bending and twisting under the moment of 10Nm and compression under the force of 1000N were considered, respectively and finally, FE analyses were performed. Results of three fixture types were compared, such as Range of Motion and maximal stress, and so on. For ROM, the screw type was average 58% less than the wedge type and was average 42% less than the plate type under all loading conditions. For average stress ratio at closer nodes between vertebra and each fixture, the wedge type was the lowest as minimum 0.02 in twisting, screw types were the highest as maximum 0.28 in compression. As the results of using cement material, it was predicted that the instability problem of the wedge type was better solved. The screw type which could be increased by implanting depth according to the number of assembling mid screws, showed that the decreased tendency of ROMs and maximal cancellous bone stresses. In further study, controlling the number of assembling screws that was suitable for a patient's bone quality, development of surgical tools and keeping on design supplementations, which will be able to develop the competitive artificial disc.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2012년도 춘계학술대회 논문집
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• pp.741-742
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• 2012