• Title/Summary/Keyword: spinal load

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Biomechanical Effect of Total Disc Replacement on Lumbar Spinal Segment : A Finite Element Analysis (추간판 치환술이 요추분절에 미치는 생체역학적 영향 : 유한요소해석)

  • Park, Won-Man;Kim, Ki-Tack;Hong, Gyu-Pyo;Kim, Yoon-Hyuk;Oh, Taek-Yul
    • 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.

Suggestion of Structural Analysis Model Using Auxiliary Rehabilitation Device for a Patient of Spinal Curvature (척추측만증 환자의 재활 치료 보조기 개발을 위한 구조 해석 모델 제시)

  • Bak, Jeong-Il;Yoon, Ho-Cheul;Kou, Heung;Yum, Deuk-Joon;Sun, Dong-Youn;Kim, Young-Chul
    • Proceedings of the IEEK Conference
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    • 2009.05a
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    • pp.141-144
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    • 2009
  • The purpose of this study is to develop the auxiliary rehabilitation device for a patient of spinal curvature. The adolescent diopathic scoliosis(AIS) must be treated by rehabilitation brace if Cobb angle is $20^{\circ}{\sim}40^{\circ}$. The rehabilitation brace is consist of 4 vest and 2 hinge parts(hinge and couple bar) that give a force to the ribs. But thin and light hinge parts for young patient failed easily because of unusual movement of the upper body. We studied optimum design and structural analysis of hinge parts when it distorted by tensile and bending force. The specimen of hinge parts were tested to evaluate the failure strength. And we attached circuits with memory and sensor detecting pressure and displacement to recoding stress in hinge parts. These data are used to alarm the patient to stop unusual movement and understand the load history.

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Prediction of Mechanical Behaviors of Bio-mechanical Materials (생체공학용 척추경 나사의 기계적 거동 예측)

  • Park, Joon-Sik;Choi, Jin Hwa;Cho, Myeong-Woo;Choi, Gil-Woon
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.3 no.1
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    • pp.72-78
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    • 2004
  • In this paper, mechanical behaviors of developed pedicle screw system, made of bio-mechanical materials(Ti-6Al-4V, Grade 5), ale predicted using FEM analysis. As a first step, morphologic construction of normal Korean spines and surgical operation convenience are considered to design optimum pedicle screw system. In this step, various design variables are considered as design parameters to develop optimized models. As a next step, tension and bending tests are performed to improve the structural performance of the developed system using finite element method. In this step, required Static compression and bending test specifications by ASTM F-04 25 04 01 are applied to understand the bio-mechanical behaviors of the designed spinal implant system under various load types. As the results of this research, it is possible to develop efficient pedicle screw system, having enough rigidity and fixation to stand any spinal damage under allowable stress conditions.

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Biomechanical analysis of pullout strength of the pedicle screws in relation to change bone mineral density (반복 하중 후 골밀도 감소에 따른 척추경 나사못의 고정력(Pullout Strength)감소 형태 분석)

  • Jung, D.Y.;Lee, S.J.;Kim, D.S.;Shin, J.W.;Kim, W.J.;Suk, S.I.
    • Proceedings of the KOSOMBE Conference
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    • v.1998 no.11
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    • pp.155-156
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    • 1998
  • Screw loosening and subsequent pullout can be attributed to the reduction in bone mineral density in the vertebrae manifested by osteoporosis in which the decrease in fixation strength between the cancellous bone and screw threads are accelerated by repeated loads exerted by patients own weight and activities following the surgery. In this study, the change in pullout strength of the pedicle screws was investigated before and after repeated loads were imparted. For this purpose. Diapason pedicle screws $(6.7\times40mm)$ were inserted onto fresh porcine spine specimens (T1-L5) after bone mineral density was measured using a DEXA. With an MTS, an axial load was applied at a loading rate of 0.33mm/sec until failure to measure the maximum pullout strength. Flexion moment of 7.5N-m was then imparted at 0.5Hz for 2000 cycles. It was found that the maximum pullout strength was exponentially related to BMD regardless of load types ($107.71\;\times\;\exp^{(1.43{\times}BMD)}r^2=0.93$, P<0.0001 without repeated load; ($107.71\;\times\;\exp^{(2.19{\times}BMD)}r^2=0.78$, P<0.0001 with repeated load). The results suggest that the reduction in pullout strength for pedicle screws is far more prominent in osteoporotic spine than in normal spine especially as number of repeated load was increased. More importantly, it was demonstrated that the level of bone mineral density and the activity level of the patient should be evaluated in more detail for successful implementation of pedicle screw systems in spinal surgery.

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Effect of Dietary Calcium on Spinal Bone Fusion in an Ovariectomized Rat Model

  • Cho, Jae-Hoon;Cho, Dae-Chul;Yu, Song-Hee;Jeon, Young-Hoon;Sung, Joo-Kyung;Kim, Kyoung-Tae
    • Journal of Korean Neurosurgical Society
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    • v.52 no.4
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    • pp.281-287
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    • 2012
  • Objective : To evaluate the effect of calcium supplementation on spinal bone fusion in ovariectomized (OVX) rats. Methods : Sixteen female Sprague Dawley rats underwent bilateral ovariectomy at 12 weeks of age to induce osteoporosis and were randomly assigned to two groups : control group (n=8) and calcium-supplemented group (OVX-Ca, n=8). Autologous spinal bone fusion surgery was performed on both groups 8 weeks later. After fusion surgery, the OVX-Ca group was supplemented with calcium in drinking water for 8 weeks. Blood was obtained 4 and 8 weeks after fusion surgery. Eight weeks after fusion surgery, the rats were euthanized and the L4-5 spine removed. Bone fusion status and fusion volume were evaluated by manual palpation and three-dimensional computed tomography. Results : The mean fusion volume in the L4-5 spine was significantly greater in the OVX-Ca group ($71.80{\pm}8.06mm^3$) than in controls ($35.34{\pm}8.24mm^3$) (p<0.01). The level of osteocalcin, a bone formation marker, was higher in OVX-Ca rats than in controls 4 weeks ($610.08{\pm}10.41$ vs. $551.61{\pm}12.34$ ng/mL) and 8 weeks ($552.05{\pm}19.67$ vs. $502.98{\pm}22.76$ ng/mL) after fusion surgery (p<0.05). The level of C-terminal telopeptide fragment of type I collagen, a bone resorption marker, was significantly lower in OVX-Ca rats than in controls 4 weeks ($77.07{\pm}12.57$ vs. $101.75{\pm}7.20$ ng/mL) and 8 weeks ($69.58{\pm}2.45$ vs. $77.15{\pm}4.10$ ng/mL) after fusion surgery (p<0.05). A mechanical strength test showed that the L4-5 vertebrae in the OVX-Ca group withstood a 50% higher maximal load compared with the controls (p<0.01). Conclusion : Dietary calcium given to OVX rats after lumbar fusion surgery improved fusion volume and mechanical strength in an ovariectomized rat model.

Effects of Disc Degeneration on Biomechanical Behaviors of the Intevertebral Disc: A Biomechanical Analysis (퇴행성으로 인한 추간판의 생체역학적 거동에 대한 분석)

  • Lee Hyun-Ok;Lee Sung-Jae;Shin Jung-Woog;Shin Tae-Jin
    • The Journal of Korean Physical Therapy
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    • v.12 no.3
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    • pp.455-467
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    • 2000
  • The purpose of this study was to analyse the effects of disc degeneration on the biomechanical behaviors of the intervertebral disc in term of axial displacement, intradiscal pressure. disc bulge at the 1.4-1.5 functional spinal unit(FSU). The degeneration is divided 4 grade by initial intradiscal pressure: normal: 135kPa. mild: 107kPa. moderate: 47kPa, severe: 15kPa, The predicted results were follows: 1. The magnitude of the bulge is found to be maximum at the anterior, minimum at the postero-lateral portion. The bulge of lateral, postero-lateral is found to be maximum in severe grade. followed by moderate. mild, normal grade. 2. Tho displacement was increased with increasing compressive load in all four grades.'rho stiffness of disc was found to be reduced by progressing from normal to severe grade. 3. The intradiscal pressure was increased nearly linearly with increasing compressive load in normal and mild grade. But the increasing rate in moderate and severe grade was showed apparently different from nomal and mild grade. Specially, it was increased very slightly in severe grade. In conclusion, decreased intradiscal pressure resulted in increase of axial displacement and disc bulge with compressive load increasing. these may compromise the nerve root impingement or irritation. Therefore posture and activities must be focus to reduce compressive load applied on the back or disc.

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Analysis of Whiplash by Rear End Collisions Using a Cervical Spine Model with Preloaded Muscles (근력을 적용한 경추 모델의 후방 충돌 해석)

  • Oh, Hyun-Woo;Yang, Seok-Jo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.34 no.2
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    • pp.139-143
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    • 2010
  • Whiplash injuries often occur in motor vehicle collision accidents. This injury frequently occurs in the cervical region. However, the reason for this has not yet been clarified. In this study, a multi-body neck model with muscles was designed. Some muscles in the model were preloaded; these were previously determined using the concept of the follower load. Cervical spinal vertebrae, discs, and muscles were designed in accordance with the human cervical spine. The purpose of this study was to investigate the effect of preloads on muscles. The results imply that the whiplash model with preloaded muscles simulates practical situations more closely than models without preloads.

Biomechanical Characteristics of Cervical Spine After Total Disc Replacement (인공 추간판 치환술 후 경추의 생체역학적 특성)

  • Park, Won-Man;Joo, Jeung-Woo;Kim, Kyung-Soo;Lee, Ki-Seok;Kim, Yoon-Hyuk
    • 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.

Analysis of Human Neck Loads During Isometric Voluntary Ramp Efforts: EMG-Assisted Optimization Modeling Approach

  • Choi, Hyeon-Ki
    • Journal of Mechanical Science and Technology
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    • v.14 no.3
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    • pp.338-349
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    • 2000
  • Neck muscle forces and spinal loads at the C4/5 level were estimated that result from isometric voluntary ramp efforts gradually developing to maximums in flexion, extension, left lateral bending and right lateral bending. Electromyographic (EMG) activities, a three-dimensional anatomic data of the neck and a hybrid model, EMG-assisted optimization (EMGAO) model, were used. The model computed the cervical loads at 25%,50%,75%, and 100% of peak moments. The highest model-predicted C4/5 joint compressive forces occurred during flexion; $361\;({\pm}164)\;N,\;811\;({\pm}288)\;N,\;1207\;({\pm}491)\;N\;and\;1674\;({\pm}319)\;N$ in 25%, 50%, 75% and 100% of peak moment respectively. Variations in load distribution among the agonistic muscles and co-contractions of antagonistic muscles were estimated during ramp efforts. Results suggest that higher C4/5 joint loads than previously reported are possible during isometric, voluntary muscle contractions. These higher physiological loads at C4/5 level must be considered possible during orthopedic reconstruction at this level.

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EMG assessment of Muscle Fatigue on Sloping Ground When Lifting (EMG를 이용한 경사면에서의 근피로도 분석)

  • 서승록;김종석
    • Journal of Korea Society of Industrial Information Systems
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    • v.5 no.2
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    • pp.1-8
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    • 2000
  • Manual material handling(MMH)is major factor which causing physical injuries of worker at working area and frequency of low back pain(LBP) is increasing industrial accidents. Especially, working in bad circumstance such as farm, orchard, harbor loading and unloading, logging place and mining place which located in inclined slope can cause much possibility of hazard and absence of working balance can cause injuries of musculoskeletal system such as joint, bone, ligament. So, this study used EMG system to measure and evaluate muscle force information and fatigue of worker when lifting on slope. The result of measuring averaged integrated EMG(AEMG) shows multifidus muscle be used more than anything else in force. neck extensors are used at 15°, 20°frequently. generally the AEMG result shows multifidus muscle be used in force. Commonly, muscle fatigue of multifidus is higher than other muscle by analysis mean power frequency(MPF). The result of load sharing rate shows multifidus and erectorspinae which are deep spinal muscles is relatively high and neck extensor is low.

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