• Journal of Mechanical Science and Technology
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• 제15권7호
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• pp.1032-1040
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• 2001

It is widely accepted that the pressure variation of interstitial fluid is one of the most important factors in bone physiology. In order to understand the role of interstitial fluid on porous bony structure, a consideration for the biomechanical interactions between fluid and solid constituents within bone is required. In this study, a poroelastic theory was applied to investigate the elastic behavior of calf vertebral trabecular bone composed of the porous solid trabeculae and the viscous bone marrow. The poroelastic behavior of trabecular bone in a uniaxial stress condition was simulated using a commercial finite difference analysis software (FLAC, Itasca Consulting Group, USA), and tested for 5 different strain rates, i.e., 0.001, 0.01, 0.1, and 10 per second. The material properties of the calf vertebral trabecular bone were utilized from the previous experimental study. Two asymptotic poroelastic responses, the drained and undrained deformations, were predicted. From the predicted results for the simulated five strain rates, it was found that the pore pressure generation has a linearly increasing behavior when the strain rate is the highest at 10 per second, otherwise it showed a nonlinear behavior. The pore pressure generation with respect to the strain was found to be increased as the strain rate increased. The elastic moduli predicted at each strain were 208.3, 212.2, 337.6, 593.1, and 602.2 MPa, respectively. Based on the results of the present study, it was suggested that the calf vertebral trabecular bone could be modeled as a poroelastic material and its strain rate dependent material behavior could be predicted.

• 대한추나의학회지
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• 제1권1호
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• pp.45-53
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• 2000

Objectives : CHUNA therapy that removes compression of dislocated vertebral bones has positive effect, but sometimes improper CHUNA manual therapy may give rise to negative effect. The aim of this study is to make sure that cervical CHUNA manual therapy give positive effect or negative effect to the blood flow velocity of vertebral artery(VA) and basilar artery(BA) by Trancranial Doppler sonography(TCD). Methods : We performed TCD study on 20patients(male 5, female 15, mean ages 38.5 years) with diagnosis like cervical movement related disorder, headache or dizziness. After we measured mean blood flow velocity(Vm) of VA and BA before cervical CHUNA therapy(Pre-CCT) and after cervical CHUNA therapy(Post-CCT), statistically evaluated the results. Results: The patients received cervical CHUNA therapy for TA sequel, HIVD of cervical spine, headache, dizziness, neck stiffness etc. VA Vm was $31.9{\pm}8.0cm/sec$ before CHUNA therapy, but significantly increased $35.0{\pm}8.7cm/sec$ after CHUNA therapy (p < 0.05). But, there was no significant variation of BA Vm between $41.8{\pm}7.5cm/sec$ Pre-CCT and $41.2{\pm}8.5cm/sec$ Post-CCT(p>0.05). Though VA Vm slightly increased after CHUNA therapy in normal range group, there was no significant variation between VA Vm Pre-CCT and VA Vm Post~CCT. In VA Vm decrease group, VA Vm significantly increased after CHUNA therapy(p<0.05). But, there was no significant variation of BA Vm between Pre-CCT and Post-CCT in BA Vm normal range group and BA Vm decrease group(p>0.05). Conclusions: These findings suggest that cervical CHUNA manual therapy have positive effect on blood flow velocity of VA and BA.

• 한국정밀공학회지
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• 제23권4호
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• pp.176-182
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• 2006

Although several artificial disc designs have been developed for the treatment of discogenic low back pain, biomechanical changes with its implantation were rarely studied. To evaluate the effect of artificial disc implantation on the biomechanics of functional spinal unit, a nonlinear three-dimensional finite element model of L4-L5 was developed with 1-mm CT scan data. Biomechanical analysis was performed for two different types of artificial disc having constrained and unconstrained instant center of rotation(ICR), ProDisc and SB Charite III model. The implanted model predictions were compared with that of intact model. Angular motion of vertebral body, forces on the spinal ligaments and facet joint, and stress distribution of vertebral endplate for flexion-extension, lateral bending, and axial rotation with a compressive preload of 400N were compared. The implanted model showed increased flexion-extension range of motion compared to that of intact model. Under 6Nm moment, the range of motion were 140%, 170% and 200% of intact in SB Charite III model and 133%, 137%, and 138% in ProDisc model. The increased stress distribution on vertebral endplate for implanted cases could be able to explain the heterotopic ossification around vertebral body in clinical observation. As a result of this study, it is obvious that implanted segment with artificial disc suffers from increased motion and stress that can result in accelerated degenerated change of surrounding structure. Unconstrained ICR model showed increased in motion but less stress in the implanted segment than constrained model.

• Journal of Trauma and Injury
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• 제20권2호
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• pp.101-105
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• 2007

Purpose: This study aimed to find any difference in the clinical or the anatomical findings of vertebral artery dissection (VAD) between the trauma and the non-trauma groups. Methods: We retrospectively reviewed the clinical data and radiologic images of VAD patients. We compared data on symptoms, neurologic deficit, National institutes of health stroke scale (NIHSS) at admission, Rankin score (RS) at admission and discharge, and radiological findings including anatomical features, between the trauma and the non-trauma groups. Results: From January 1997 to May 2006, 42 patients were enrolled and 13 patients (31%) had a history of earlier trauma. Focal neurologic deficit (trauma group 11/13 vs. non-trauma group 11/29), cerebral stroke (10/13 vs. 9/29), and extradural lesions of dissection (6/13 vs. 3/28) were more common in the trauma group than non-trauma group (p=0.007, p=0.017, p=0.018, respectively) and NIHSS at admission and discharge were significantly higher (p=0.012, p=0.001, respectively). Dissecting aneurysms were less frequent in the trauma group (2/13 vs. 19/29, p=0.006). Subarachnoid hemorrhage and unfavorable prognostic value (Rankin score at discharge ${\geq}$ 2) showed no differences between the groups (p=0.540, p=0.267, respectively). Conclusion: In VAD patients after trauma, focal neurologic deficit due to ischemic stroke and a steno-occlusive pattern are more frequent than they are in non-trauma patients. The location of dissection was most frequent at the extradural vertebral artery in the trauma group. NIHSS was higher in the trauma groups but the incidence of an unfavorable prognostic value (RS ${\geq}$ 2) was not significantly different between the groups.

• 척추신경추나의학회지
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• 제9권2호
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• pp.93-113
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• 2014

Objectives : This study aims to evaluate domestic/foreign clinical studies related to the traction therapy and analyse points to consider about cervical/lumbar traction therapy. Methods : Seven databases were searched for related articles about cervical/lumbar traction therapy from 1950 to 2014. Fourteen clinical studies and several systemic reviews were included among 144 studies searched. Out of fourteen clinical studies, four were case series and ten were controlled trials. Results : Most of included studies reported favorable effects of traction group compared to baseline of controlled group. The various mechanical factors most relevant to traction are 1) angle of pull and direction, 2) traction force, 3) duration of traction and frequency of treatment. Conclusions : We found various mistake in the applications of statistical methodologies of traction therapy targeting patients of cervical, lumbar vertebral disease. It is necessary for more randomized controlled trials to evaluate effect of cervical/lumbar traction therapy targeting patients of cervical, lumbar vertebral disease.

• Journal of Korean Neurosurgical Society
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• 제39권2호
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• pp.92-95
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• 2006

Objective : Severe vertebral body collapse [vertebra plana] is considered a contraindication to vertebroplasty by most authors. The purpose of this study is to determine the efficacy of vertebroplasty in treating severe compression fracture patients with osteoporosis. Methods : 16 patients underwent 18 vertebroplasties following postural reduction for vertebra plana. The fractures were defined vertebrae that have collapsed to more than 75% of their original height. Imaging and clinical features were analyzed, including involved vertebrae level, vertebral height after postural reduction for 2 days, injected cement volume, clinical outcome and complications. Results : Involved veretebra were located from level T7 to L4. Vertebral body collapse averaged 79% [range $12{\sim}25%$] of the original height. After pillow reduction for 2 days, vertebral body height increased 35% of the original height [range $15{\sim}45%$]. The kyphotic wedge was $12^{\circ}$ before procedure and was decreased $7.0^{\circ}$ after vertebroplasty. The mean injected cement volume was 3.8ml [range $2.0{\sim}4.9ml$]. After the procedure, surgical outcome was excellent in 8 [50%] of 16 patients, good in 7 [42%] and unchanged in one [8%]. The mean pain score [VAS score] prior to vertebroplasty was 8.3 and it changed 3.2 after the procure. Cement leakage to the adjacent disc [5 cases] and paravertebral soft tissues [4 cases] developed but there were no major complications. Conclusion : We propose that vertebra plana due to osteoporosis is not a contraindication to vertebroplasty. Vertebroplasty following postural reduction for severe compression fracture is safe and effective treatment.

• Journal of Korean Neurosurgical Society
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• 제52권6호
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• pp.513-516
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• 2012

Objective : It is rare that the medial loop in the V2 segment of the vertebral artery (VA) causes compression of the proximal cervical root of the spinal cord without leading to bony erosion and an enlarged foramen. We evaluated the clinical significance and incidence of the medial loop in the V2 segment of the VA. Methods : We reviewed the records from 1000 consecutive patients who had undergone magnetic resonance imaging evaluation of the cervical spine between January 2005 and January 2008. The inclusion criteria were that over a third of the axial aspect of the VA located in the intervertebral foramen was inside the line between the most ventral points of the bilateral lateral mass, and that the ipsilateral proximal root deviated dorsally because of the medial loop of the VA. We excluded cases of bone erosion, a widened foramen at the medial loop of the VA, any bony abnormalities, tumors displacing VA, or vertebral fractures. The medical records were reviewed retrospectively to search for factors of clinical significance. Results : In six patients (0.6%), the VA formed a medial loop that caused compression of the proximal cervical root. One of these patients had the cervical radiculopathy that developed after minor trauma but the others did not present with cervical radiculopathy related to the medial loop of the VA. Conclusion : The medial loop of the VA might have a direct effect on cervical radiculopathy. Therefore, this feature should be of critical consideration in preoperative planning and during surgery.

• Journal of Korean Neurosurgical Society
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• 제52권5호
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• pp.435-440
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• 2012

Objective : The purpose of this study is to find the optimal stiffness and volume of bone cement and their biomechanical effects on the adjacent vertebrae to determine a better strategy for conducting vertebroplasty. Methods : A three-dimensional finite-element model of a functional spinal unit was developed using computed tomography scans of a normal motion segment, comprising the T11, T12 and L1 vertebrae. Volumes of bone cement, with appropriate mechanical properties, were inserted into the trabecular core of the T12 vertebra. Parametric studies were done by varying the volume and stiffness of the bone cement. Results : When the bone cement filling volume reached 30% of the volume of a vertebral body, the level of stiffness was restored to that of normal bone, and when higher bone cement exceeded 30% of the volume, the result was stiffness in excess of that of normal bone. When the bone cement volume was varied, local stress in the bony structures (cortical shell, trabecular bone and endplate) of each vertebra monotonically increased. Low-modulus bone cement has the effect of reducing strain in the augmented body, but only in cases of relatively high volumes of bone cement (>50%). Furthermore, varying the stiffness of bone cement has a negligible effect on the stress distribution of vertebral bodies. Conclusion : The volume of cement was considered to be the most important determinant in endplate fracture. Changing the stiffness of bone cement has a negligible effect on the stress distribution of vertebral bodies.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.169-170
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• 1998

In this study, regional variation in vertebral bone density due to osteoporosis were investigated using a method that employs images from QCT. QCT images(1mm thick slices) of the first lumbar vertebra from a normal person (23/M, BMD=139.8mg/ml) and from an osteoporotic patient (54/F, BMD=82.0mg/ml) were obtained. Uniform settings (140kVp, 204mA) were used and images of 300 Hounsfield Unit or greater were selectied to filler out soft tissue interference. To assess the regional variation of the area fraction the vertebral body was divided into 3 layers and each layer contained 9 regions. Area faction was calculated based on image analysis data. Our results showed that the area fraction at the middle of the vertebra was quite lower than the endplate and peripheral regions, but the area fraction values from the osteoporotic patient were uniform throughout the entire height of the vertebral body, which indicates the significant drop of BMD had occurred near both end-plates due to the osteoporosis, especially at the peripheral regions. Our results suggest the susceptability of the vertebrae to compression fracture types in osteoporotic spine.

• Journal of Trauma and Injury
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• 제27권4호
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• pp.186-191
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• 2014

Purpose: The objectives of this study were to assess pain relief according to the time after kyphoplasty and to evaluate the factors affecting pain relief after kyphoplasty in the treatment of a single-level osteoporotic vertebral compression fracture. Methods: A retrospective review of 34 kyphoplasties for single-level osteoporotic vertebral compression fractures was performed. Pain relief was assessed by using the visual analogue scale (VAS) at preoperatively and postoperatively at 6 weeks, 3 months, and 6 months. Associated factors, including age, sex, pain duration, bone mineral density, and cement leakage, were evaluated using the patients' medical records. Statistical analyses were conducted using the paired t-test to assess pain relief and using the independent t-test and Pearson's correlation coefficient to evaluate the relationship between those factors and pain relief. Results: Preoperatively, the mean VAS score was 7.06. Postoperatively, it declined to 3.66 (p=0.001), 2.81 (p=0.001) and 2.24 (p=0.001) at 6 weeks, 3 months and 6 months, respectively. Also, statistically significant pain relief was observed during the periods from 6 weeks to 3 months (p=0.001) and from 3 months to 6 months (p=0.001). However, reduction of the VAS score showed no significant correlation with age, sex, pain duration, bone mineral density, or cement leakage (p>0.05). Conclusion: Our study suggests that a kyphoplasty may be effective in osteoporotic vertebral compression fracture patients with acute pain and that after the kyphoplasty, pain is reduced remarkably for 6 weeks and then continuously for 6 months.