Hungarian Society of Biomechanics: E-Journals / Magyar Biomechanikai Társaság
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Application of fingertip support technique in microsurgery
Get PDFObjectiveThe physiological tremor which may extend up to 0.4–0.6 mm on the instrument tip in case of a well-skilled microsurgeon may cause diffi culties in any fi eld of microsurgery, in spite of using different armrests. The limit of correctness of medical robots is about 0.1 mm so far, but the application of these machines is expensive and not convenient for surgeons because the direct touch via microinstruments with living tissues is impossible.MethodThe effectiveness of the fi ngertip support technique has been proven by randomized analysis by exact measuring of the reduction of tremor.ResultsThe 0.1 mm precision could be reached by fi ngertip support. This extra precise work has not been available by hand so far.ConclusionThe signifi cant effect of fi ngertip support technique in neurosurgery has been certifi ed and published by exact measuring and clinical data.Our hypothesis could be the indication for trials in any microsurgical work. DOI: 10.17489/biohun/2010/1/0
Effect of percutaneous vertebroplasty on adjacent vertebrae: a preliminary biomechanical study
Get PDFAz elõzetes biomechanikai vizsgálatban a szerzõk az osteoporosis talaján kialakult kompreszszióscsigolyatörések kezelésében alkalmazott perkután csigolyastabilizációs módszerek, avertebroplasztika és kyphoplasztika szomszédos csigolyatestekre gyakorolt hatásait vizsgálták.A vizsgálatot három csigolyatestet tartalmazó funkcionális gerincegységek végezték nyomóterhelésalkalmazásával. A funkcionális gerincegységek középsõ csigolyáját elõzetesen vertebroplasztikávalvagy kyphoplasztikával kezelték. Az eredmények azt mutatják, hogy a kidolgozottmódszer alkalmas egy nagyobb mintaszámú összehasonlító vizsgálat elvégzésére, amely választadhat arra a kérdésre, hogy a két perkután csigolyastabilizációs módszer szomszédos csigolyákragyakorolt biomechanikai hatásában van-e különbség. DOI: 10.17489/biohun/2009/2/03In this preliminary study the authors have evaluated the biomechanical effect of two differentpercutaneous vertebral augmentation techniques – vertebroplasty and kyphoplasty – on adjacentvertebral bodies. The in vitro study was performed by applying compressive load on functionalspinal units containing three vertebrae. The middle vertebral body was previously treatedwith one of the above mentioned techniques. The results showed that the applied technologyis feasible for performing a larger sample size study to compare vertebroplasty andkyphoplasty in terms of their biomechanical effects on adjacent vertebrae
Correspondence of biomechanical changes in respect of pain score and psychological status after the standard and enhanced spine stabilisation trainings
Get PDFLow back pain is one of the leading causes of disability. Exercise therapy is a management strategy that is widely used in low back pain. The aim of our study was to investigate the results of standard and enhanced exercise therapy. 15 patients who had low back pain were involved in the study, none of the patients had had spinal operations before. In the fi rst group the patients did the exercises every day at home. The patients of the second group did the exercises 3 times a week. For the biomechanical measurement we used the Spinal Mouse, a computer associated device, based on electromagnetic impulses. For estimating pain we used the 3D pain questionnaire (West-Haven-Yale Multidimensional Pain Inventory [WHYMPI]).In the outline analysis there was a signifi cant rise in the capacity (
Fusion of video and motion data: engineering tasks and clinical applicability
Get PDFStatus of a new project – focusing on technical aspects of fusion of live video and data from optical motion tracking – is summarized. Also, the signifi cance of development in two areas is marked out: (1) in clinical fi eld of endoscopic surgeries as demonstrating and training tool; (2) in biomechanical research for accurate detection of human motion curves. DOI: 10.17489/biohun/2010/1/2
Study and examination of the implements used for securing pelvis bone
Get PDFOur goal was to compare the direct plate known as the “gold standard” technology in case of a pelvis fracture with the H-plate technology reinforced with iliolumbar fusion and the pelvis screwing technology reinforced with iliolumbar fusion, especially focusing on the matter of stability.In our work we studied and examined the securing possibilities and stability of the transforaminal pelvis fracture using the finite element analysis. My colleauges and I created the anatomically correct model (including the 4th and 5th lumbars and cartilages under the lumbars). To create the model we used a previous geometric model used for older preceding analyses. During the modeling we perfected the geometry; we separated the different bone regions and paid close attention to create the scale model of the implements. The placements of the implements are appropriate and in accordance with real surgery procedures. We examined three different cases: standing on the healthy leg, standing on both legs and standing on the injured leg. The boundary conditions for the finite element analysis: the femur is fi xed and in case of standing on one leg the opposing side of the hip bone is fixed on both the X and Z axes directions. Furthermore both hip bones are fixed on the Y axis direction, and this applies when standing on both legs as well. We added the load to the 4th lumbar on the model. The value of the load is 500 N and the direction is –Z. We defined surface to surface connection between the femur and acetabulum and also between the side of the symphysis pubica and the fracture ends. We defined bonded connection between all the other components. In our analyses and evaluation we examined the arising stress values and also the displacements in the cortical and spongiosa regions and in the implements. We examined the elongation of the ligaments in the pelvis and measured the maximal distance between the fracture ends under load.Considering the results of the stress states, the iliolumbar fusion technologies provide more stability. Therefore it is recommended to use these technologies, not mentioning the fact that the dorsal exposure puts the patient through considerably less trauma.Considering the results of the fracture ends displacements it can be declared that the reason for the existence of the H-plate technology reinforced with iliolumbar fusion cannot be questioned. Therefore continuing the research can be justifi ed by further analyzing and examining dynamic loads on models extracted from CT images. DOI: 10.17489/biohun/2010/1/2
Analysis of the mechanical behaviorof discrete elements in fluids (from the continuum to the discrete)
Get PDFDOI: 10.17489/biohun/2010/1/3
Force measurement of hand and fingers
Get PDFObjective: To determine forces of hand and fi ngers in model situations.Methods: Subjects were 16 university students (males). Dyna-8 force measuring system was used, which is equipped with transducers making the measurement of handgrip strength andforces of fi ngers possible. The maximum force value is displayed digitally and simultaneously, the complete force diagram is shown on the computer monitor.Results: Right and left hand strengths and forces of all fi ngers were recorded, and descriptive statistics, correlation analysis, and t-test were executed. Forces of right and left hand strengths correlate, but differ signifi cantly when their means are compared. Forces of the same fi ngers on the right and left hand correlate signifi cantly with the exception of the middle and index fi ngers.Conclusion: Hand and fi nger force data are used in numerous sport types, industrial design, ergonomics, and rehabilitation. DOI: 10.17489/biohun/2010/1/0
Mechanical properties of coronary vein – in vitro evaluation of longitudinal and transversal samples
Get PDFAims: Even though several publications are available and experiments were done in the topic of the mechanical properties of vessels there is no data for special veins like coronary veins. Previously a few rectangular coronary vein parts had been examined and the results show that probably there is a difference between the transversal and longitudinal direction of coronary vein. The aim of this study is to investigating the differences in the mechanical properties of the two directions with in vitro tensile tests.Method: Coronary veins from six pig hearts were tested within one hour after explantation. Five transversal and nine longitudinal coronary vein samples were prepared from these hearts and kept in physiologic solution until the tests. The samples were evaluated in 37 °C physiologic solution with tensile equipment and the force-displacement curves were recorded. Based on these curves and the tearing results the longitudinal and transversal tensile strengths, relative extensions and Young’s modulus were calculated.Results: The evaluation squarely proved the differences of mechanical properties between the longitudinal and transversal directions of coronary vein samples. Transversal direction had higher elongation properties (248±117% vs. 137±37%) but lower resistance to mechanical loading (0.99±0.16 MPa vs. 2.55 ± 0.46 MPa) than the longitudinal direction.Conclusion: The experiments are successfully investigated the mechanical differences of coronary vein directions. These are important parameters, because in case of special application the maximal elongation capability and the maximal force that the vein can tolerate without injury had to be known. With the result of these experiments the maximal loading concerning to coronary veins can be modelled. However there are still question to answer for example the individual role of the different layers of coronary veins which is not known during the mechanical testing.Further investigations are necessary to perform in order to have a complete analysis of mechanical properties of coronary veins. DOI: 10.17489/biohun/2010/1/0
Examination of pregnant women’s gait per trimesters with stabilometry
Get PDFCélkitűzésekA várandósság hatással van a testtartásra és így a járásra, mint a dinamikus testtartás egy képviselőjére. Célunk volt bizonyítani ezen élettani változások hatásait a járásra.Adatok és módszerekAz utánkövetéses vizsgálatban, melyet a PTE ÁOK Szülészeti és Nőgyógyászati Klinikáján végeztünk 2008 májusától 2009 februárjáig, 42 nő vett részt: 21 várandós az I., a II. és a III. trimeszterben, és 21 nem terhes és még nem szült nő alkotta a kontrollcsoportot.EredményekA stabilométeres mérések szerint a várandósok járása lassabb, mint a kontrollcsoporté (p=0,046), de a lépésciklus ideje a terhesség előrehaladtával csökken. A trimeszterekben mért lengőfázis ideje rövidebb a kontrollcsoporthoz képest. A kettőstámaszok aránya a teljes lépésciklushoz képest, a kontrollcsoporttal összehasonlítva trimeszterenként nőtt. A gördítés vizsgálatánál a kontrollcsoport és a kismamák I. trimeszterben mért adatai között szignifi káns különbséget találtunk (p=0,006). Az I. trimeszterben lévő kismamáknál mért lábszög nagyobb a kontrollcsoporténál (p=0,029). A kismamák I. trimeszterben mért lépésszélessége a kontrollcsoportéhoz képest kisebb (p=0,002). A várandós nők I. és III. trimeszterben mért lépésszélességét összehasonlítva szignifi káns növekedést tapasztaltunk (p=0,049).KövetkeztetésekKimutattuk, hogy a járás kinematikája megváltozik a terhesség folyamán, illetve eltérést mutat a kontrollcsoporthoz képest. DOI: 10.17489/biohun/2010/1/09Pregnancy has an impact on posture and so on walking as well, as it is a representative of the dynamic posture. Our aim was to demonstrate the effects of these physiological changes on walking.The follow-up research was conducted at the Medical School of the University of Pécs Department of Obstetrics and Gynaecology Clinic from May 2008 to February 2009. 42 women participated in it. 21 pregnant women in the I., II. and III. trimester of their pregnancy were involved and 21 non-pregnantwomen, who had not gave birth yet, formed the control group.According to the stabilometric measurements the pregnant women’s gait is slower than the control group’s gait (p = 0.046), but the period of the gait cycle decreases in course of pregnancy. The duration of the swing phase measured during the trimesters are shorter compared to the control group. The proportion of the double-support stance period in the whole gait cycle, increased during the trimesters in comparison with the control group. The test of the midstance showed signifi cant difference (p = 0.006) between the control group and the pregnant women in the fi rst trimester. The foot angle of the expectant mothers in the fi rst trimester is bigger than the footangle of the control group (p = 0.029). The step width of the pregnant women in the fi rst trimester is smaller than the control group’s step width (p= 0.002). The comparison of the step width of pregnant women in the fi rst and third trimester, showed a signifi cant increase (p = 0.049).We have shown that the kinematics of gait changes during pregnancy and differs from the controlgroup