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1.
目的 研究髓内钉结合辅助钢板固定胫骨近端1/3骨折的稳定性,比较并观察胫骨近端1/3骨折后内侧辅助钢板与前外侧辅助钢板结合髓内钉固定的生物力学特点。方法 选取Sawbones第4代人工胫骨模型。根据辅助钢板位置分为后内侧钢板组和前外侧钢板组,每组4例,髓内钉远近端均2枚锁定钉固定,钢板远近端各3枚皮钉双层皮质固定。模拟AO分型41-A2型骨折,水平截骨平面位于胫骨髓内钉近端锁定钉远端0.5 cm即近端关节面以远5~6 cm位置。截骨完成后,通过生物力学试验机分别进行轴向压缩、三点弯曲、循环加载及极限应力测试,比较各组轴向刚度、三点弯曲刚度等结果。结果 轴向压缩实验表明,后内侧钢板组平均轴向刚度低于前外侧钢板组,两组间差异无统计学意义。三点弯曲实验表明,后内侧钢板组无论是对抗内翻应力(钢板位于骨折压力侧,t=3.679,P<0.05)还是外翻应力(钢板位于骨折张力侧,t=8.975,P<0.05),其弯曲刚度均优于前外侧钢板组。结论 辅助钢板结合髓内钉固定胫骨近端1/3骨折可以提高近端骨折块固定的稳定性,并允许患者更早负重。钢板置于后内侧或者前外侧均能够提供足够的轴向强度,后...  相似文献   

2.
目的 本研究利用高分辨率显微磁共振成像(micro-magnetic resonance imaging,μMRI)在呈现骨微结构方面的优势和对人体无辐射的优点,结合有限元分析(finite element analysis,FEA),无创探究人体在自然站立状态下股骨近端微观力学行为,明确股骨易骨折危险区域,为μMRI-FEA未来临床应用提供理论基础。方法 采集5例年龄55~63岁女性志愿者(58.4岁±3.4岁)的股骨近端μMRI图像。将图像中骨骼和软组织分割,三维重建得到包含股骨近端皮质骨和松质骨微结构的大尺度三维有限元模型(约一千万六面体单元),赋予非均匀材料属性。模拟人体自然站立时股骨的受力,将其远端固定,在股骨头部位施加压缩载荷,进行线弹性有限元分析,得到股骨近端的应力和应变分布,并选取股骨颈和大转子部位10 mm~3松质骨感兴趣区域进行比较。结果 人体自然站立姿态下,股骨颈上、下侧皮质骨分别出现拉、压应力集中现象。股骨颈松质骨感兴趣区域在上下(superior-inferior,SI)、内外(medial-lateral,ML)和前后(anterior-posterior,AP)三个方向上的正应力(σ_(SI)、σ_(ML)、σ_(AP))分别为大转子部位的13.4倍、2.2倍和1.9倍;正应变(ε_(SI)、ε_(ML)、ε_(AP))分别为大转子部位的7.4倍、5.0倍和4.0倍。结论自然站立时股骨颈皮质骨和松质骨所受应力和应变较大,提示股骨颈是易发生骨折的高危区域,与临床观察一致。本研究为μMRI-FEA未来应用于临床无创评估股骨骨折风险进而鉴别骨折高风险人群提供了一定的前期理论支撑。  相似文献   

3.
目的探讨内侧支撑螺钉在肱骨近端锁定钢板固定肱骨近端骨折中的生物力学性能。方法将30个人工合成左侧肱骨随机分成3组,建立外科颈骨折模型,采用肱骨近端锁定钢板固定:A组,近端内侧骨皮质支撑,无内侧支撑螺钉;B组,3枚内侧支撑螺钉支撑,无内侧骨皮质支撑;C组,无内侧骨皮质和内侧支撑螺钉支撑。分别对3组标本进行轴向压缩、抗扭、剪切力压缩、模型失效测试。结果 A、B、C 3组轴向压缩最大载荷为A组((240.88±19.13)N)>B组((169.04±19.26)N)>C组((128.58±17.53)N),P<0.05);抗压刚度为A组((424.4±101.2)N/mm)>B组((230.7±40.54)N/mm)>C组((147.0±29.2)N/mm,P<0.05);抗扭测试最大扭矩A组((8.92±0.25)N.m)、B组((9.09±0.31)N.m)>C组((7.57±0.53)N.m,P<0.05),抗扭刚度A组((1.80±0.07)N.m/(°))、B组((1.86±0.07)N.m/(°))>C组((1.53±0.10)N.m/(°),P<0.05);剪切力压缩测试最大载荷为A组((444.71±20.87)N)>B组((228.79±28.95)N)>C组((188.73±26.15)N,P<0.05),抗压刚度为A组((470.0±54.4)N/mm)>B组((183.89±29.64)N/mm)>C组((140.2±32.1)N/mm,P<0.05);模型失效载荷A组((2 949.76±355.08)N)>B组((2 448.13±402.39)N)、C组((2 222.55±336.41)N,P<0.05)。结论肱骨近端内侧骨皮质支撑具有最佳的生物力学性能,采用3枚内侧支撑螺钉重建肱骨近端内侧柱支撑的生物力学性能较无内侧柱支撑时明显增强。通过内侧骨皮质支撑或内侧支撑螺钉重建肱骨近端内侧柱支撑值得临床运用,以预防术后内固定失败。  相似文献   

4.
人体腰椎松质骨的生物力学性质   总被引:5,自引:0,他引:5  
本文以三具新鲜男性尸体的T12~L4椎体的松质骨为材料,通过准静态压缩试验,分析了应变率(ε)表观密度(ρa)和组织密度(ρt)对松质骨弹性模量、强度和终应变的影响。试验采用了5个应变率1.0×10-5,5.0×10-5,1.0×10-4,5.0×10-4,1.0×10-3S-1。松质骨的表观密度和组织密度范围分别为0.46~0.71g/cm3,1.02~1.54g/cm3。以弹性模量、强度和终应变为因变量(Y),以应变率和表观密度或组织密度为自变量。利用以下模型进行了非线性回归分析:Y=aρbaεc。当b分别取1.88,2和3时,弹性模量与应变率的关系均可用上面模型表达,其指数c分别为0.07,0.1,0.1。弹性模量与表观密度呈1.88次方关系,强度与表观密度呈1.29次方关系。终应变作为独立变量不受表观密度和应变率的影响。组织密度的平方和立方均与弹性模量正相关  相似文献   

5.
目的 比较膝关节单髁置换术(unicompartmental knee arthroplasty, UKA)常规截骨、保留圆角截骨及全新扩大圆角截骨方法对术后胫骨近端生物力学特性的影响。方法 基于Sawbones胫骨的CT数据,构建完整胫骨模型及不同截骨方式下UKA术后胫骨模型,采用轴向压缩工况对模型进行有限元分析,比较不同模型间胫骨近端应变情况及骨水泥应力差异。结果 在轴向压缩工况下,扩大圆角组其截骨区皮质骨von Mises应变峰值较常规截骨组与保留圆角组有所增加,而松质骨von Mises应变峰值则分别减少24.3%~42.9%、26.0%~48.7%。对比截骨区松质骨与皮质骨von Mises应变峰值差Δεpeak,发现扩大圆角组其Δεpeak远远小于其余两组。UKA后不同模型间胫骨前内侧皮质骨最小主应变无明显差异,但较完整胫骨模型增加23.3%~34.5%。扩大圆角组骨水泥单元平均von Mises应力随着圆角半径增大呈现下降趋势,且整体均小于常规截骨组与保留圆角组。结论 全新扩大圆角截骨方法可使健康骨质条件下胫骨近端应力传递更均匀...  相似文献   

6.
目的 探讨雄性大鼠肱骨、股骨和胫骨生物力学性能增龄性变化规律及其在年龄推断中的应用价值。方法 根据不同周龄,将90只健康雄性SD大鼠分为2、4、6、8、17、26、52、78和104周龄组,每组10只。过量麻醉处死大鼠后分离肱骨、股骨和胫骨并剔除附着软组织,利用游标卡尺测量上述骨骼长度及中段(受压部位)直径,利用电子万能材料试验机进行三点弯曲试验以检测极限载荷和极限载荷下位移。结果 不同周龄组雄性大鼠肱骨、股骨和胫骨极限载荷组间差异均具有统计学意义(P<0.05)。随着周龄增长,肱骨、股骨和胫骨极限载荷均呈先增大后减小趋势,且都在52周龄组达峰值,52周龄前与周龄呈强正相关(r=0.884、0.933、0.929,P<0.05)。极限载荷下位移除股骨组间差异有统计学意义外(P<0.05),肱骨、胫骨均无统计学意义。股骨极限载荷下位移与周龄呈弱正相关(r=0.406,P<0.05)。52周龄前大鼠肱骨、股骨、胫骨、3种骨骼综合极限载荷自动线性建模的年龄预测准确度分别为78.2%、86.8%、84.1%、88.3%。肱骨、股骨、胫骨长度与极限载荷呈强正相关(r=0....  相似文献   

7.
目的 研究松质骨粒移植增强和骨水泥增强对治疗节段和相邻非治疗节段的生物力学相容性 影响,探讨椎体重建前后的荷载传导机制。方法 选取正常男性青壮年脊柱L1-L2节段标本进行薄层 CT扫描,构建正常的和骨折复位后疏松的功能脊柱单元三维有限元模型,模拟经皮穿刺椎体后凸 成形术(PKP)在L2椎体核心注入骨水泥,模拟经皮骨移植(Optimesh)在L2椎体核心置入松质骨粒,按 照脊柱三柱理论施加轴向压缩、前屈和后伸荷载进行有限元分析。结果 质骨粒移植增强或骨水泥增强后相邻节段椎体应力应变的变化甚微;但是,治疗节段增强区域的应力应变明显改变。另外,骨质疏松、松质骨粒移植增强、骨水泥增强对脊柱三柱轴向压缩位移和椎间盘平均内压没有影响。结论 松质骨粒移植增强和骨水泥增强均能恢复疏松椎体的总体刚度和强 度,有利于椎体功能重建;但从椎体与增强材料间的力学相容性和生物相容性的观点看,松质骨粒 移植增强优于骨水泥增强。  相似文献   

8.
目的 分析填充块材料和尺寸对胫骨截骨模型应力分布的影响。方法 建立3种不同材料(髂骨、松质骨和聚醚醚酮)、5种不同尺寸填充块,分别植入胫骨截骨模型,对模型进行力学加载,分析模型的应力分布和边缘位移。结果 就3种材料而言,植入髂骨材料的填充块模型在胫骨近端、钢板的应力和边缘位移低于松质骨和聚醚醚酮材料,但髂骨材料的填充块应力最高;在不同尺寸填充块植入截骨间隙时,胫骨截骨各部分应力分布和边缘位移存在差异,特别是填充块宽度从30 mm减小到10 mm,胫骨近端、钢板和填充块应力峰值平均分别增加了49.3%、92.7%、54.4%。结论 不同的填充块参数会影响胫骨截骨不同部位的应力分布。研究结果为临床胫骨截骨填充块参数的选择提供理论依据。  相似文献   

9.
目的:探讨髋部骨折老年患者Singh指数与股骨近端几何结构及承重区生物力学的关系。方法:选取82例髋部骨折老年患者(观察组)与41例既往存在闭合性髋部骨折史青壮年者(对照组)的临床资料进行回顾性分析,对比Singh指数分级、股骨近端几何结构指标(股骨颈轴长、颈干角、颈长、内侧偏距)及承重区生物力学指标(骨极限应力、弹性模量),分析Singh指数与股骨近端几何结构指标、承重区生物力学指标的关系。结果:观察组Singh指数分级中Ⅱ、Ⅲ级占比高于对照组,而Ⅳ、Ⅴ、Ⅵ级占比低于对照组(P<0.05);观察组Singh指数、颈干角、骨极限应力、弹性模量低于对照组,而股骨颈轴长、内侧偏距、颈长高于对照组(P<0.05)。分层回归显示,颈干角、骨极限应力、弹性模量会对Singh指数产生显著的正向影响关系,而股骨颈轴长会对Singh指数产生显著的负向影响关系(P<0.05)。结论:髋部骨折老年患者Singh指数与股骨近端几何结构及承重区生物力学具有密切关系,Singh指数的降低会严重影响患者的股骨近端几何结构及承重区生物力学。  相似文献   

10.
目的 探讨数字化摄影技术(DR)用于骨密度测定的方法和可行性.方法 门诊健康体检成年女性194例,DR拍摄标准骨盆平片,利用DR的图像后处理工作站选取股骨颈3点,Ward三角1点,股骨大粗隆3点,测量像素密度后求平均值.按年龄分层,观察DR像素密度变化规律;与双能X线吸收法(DXA)测定的相应部位骨密度值进行相关性分析.结果 不同年龄层成年女性DR像素密度不同,DR像素密度和DXA骨密度均随年龄增长呈逐渐下降趋势;左右侧股骨颈DR像素密度和DXA骨密度呈正相关(r=0.353,0.371)(均P<0.01);左右侧Ward三角部位DR像素密度和DXA骨密度呈正相关(r=0.460,0.466)(均P<0.01);左右大粗隆部位DR像素密度和DXA骨密度呈正相关(r=0.484,0.433)(均P<0.01).结论 DR技术可用于髋部骨密度测定.  相似文献   

11.
Renal dysplasia and asplenia in two sibs   总被引:2,自引:0,他引:2  
A family is reported in which two sibs, one male and the other female, both died within 24 hours of birth with enlarged polycystic kidneys. Postmortem histology in the second child showed gross renal dysplasia. In both children the pancreas was enlarged, nodular and cystic but the liver appeared macroscopically normal. In the second child, histological examination confirmed pancreatic fibrosis with cystic dilation of ducts, but showed portal fibrosis with bile duct proliferation in the liver.
This combination of findings is very reminiscent of those in a girl and her brother reported by Ivemark et al. (1959). The children reported here also showed absence or hypoplasia of the spleen, cardiac anomalies and other features of the Ivemark syndrome (Ivemark 1955), a quite different, usually sporadic, congenital disorder. It is suggested that the children described here have a distinct lethal congenital disorder, probably inherited in an autosomal recessive manner.  相似文献   

12.
Over 200 schizophrenic patients belonging to three major and interrelated pedigree complexes have been investigated over the past 30 years in a North Swedish geographically isolated population, presently numbering about 6,000. An intensive investigation of a number of biochemical correlates and genetic markers in a few selected families belonging to one of the major pedigrees has indicated new strategies for the current research program.
Schizophrenia, as defined operationally, is significantly associated with decreased activities of two enzymes (1) blood platelet monoamine oxidase, (2) plasma dopamine-β-hydroxylase, and (3) with the genetic marker Gc2 (group specific antigen). Both enzymes are subject to genetic variation. A positive score for linkage between schizophrenia and low plasma DBH activity has been calculated, but, so far, available data are insufficient for discrimination between linkage and partial contribution of genetically controlled low plasma DBH to the pathogenesis of the disease. Alternatively, both mechanisms could be involved.
As a model for continued research, schizophrenia is explained as based on a double dominant-recessive genotype (Aabb), representing a vulnerability which in about 50 % of cases develops into clinical schizophrenia. It is suggested that the dominant mutation (A) operates on or affects MAO activity, and that the recessive genotype (bb) is instrumental in low variates of DBH activity and very likely such variates within the normal range of physiological variation. Moreover, it is suggested that the combined effects of MAO- and DBH-reduced efficiency on the metabolism of e.g. dopamine could be an essential pathogenic mechanism for the schizophrenic illness which is segregating in this population.  相似文献   

13.
About 1900, modern food selection and processing caused widespread epidemics of the B vitamin deficiency diseases of beriberi and pellagra which, for genetic reasons, often expressed as different diseases ranging from bowel and heart disease to dermatoses and psychoses. But the B vitamins merely help convert essential fatty acids (EFA) into the prostaglandin (PG) tissue regulators and it now turns out that, through hydrogenation, milling and selection of w3-poor southern foods, we have also been systematically depleting, by as much as 90%, a newly discovered trace Nordic EFA (w3) of special importance to primates and sole precursor of the PG3(4) series, even as a concurrent fiber deficiency increases body demand for EFA. Since substrate EFA is processed by many B vitamin catalysts, an EFA deficiency will mimic a panhypovitaminosis B, i.e., a mixture of substrate beriberi and substrate pellagra resembling vitamin beriberi and pellagra but exhibiting as even more diverse endemic disease. This would consitute a second stage of the Modern Malnutrition and explain why some workers now hold the dominant diseases of modermized societies to be new, nutritionally based, pellagraform yet lipid-related and to range, once again, from heart disease to psychosis. It is an assumption that our dominant diseases are unrelated to each other or are merely revealed by our diagnostic acumen and therapeutic success; and that hydrogenating millions of tons of food oils annually, to destroy the rancidity producing w3-EFA, is safe for primates. Extensive beriberiform disease is reported here in 32 typical cases taken from medical practice which responds strikingly to linseed oil supplements (60% w3-EFA) in confirmation of identical results in Capuchins.  相似文献   

14.
15.
Recent advancements in agricultural biotechnology have created a need for analytical techniques to determine introduced proteins in crops enhanced through modern biotechnology techniques. These proteins are expressed in plant tissues and may be present in food ingredients. Immunoassays are ideally suited for protein detection and may be used as both quantitative and threshold methods. Microplate ELISA and lateral flow devices are two of the most commonly used immunoassay formats for agricultural biotechnology applications. This paper provides general background information and a discussion of criteria for the validation and application of immunochemical methods to the analysis of proteins introduced into plants and food ingredients using biotechnology methods. It is the result of a collaborative effort of members of the Analytical Environmental Immunochemical Consortium. This collaborative effort represents the combined expertise of several organizations to reach consensus on establishing guidelines for the validation and use of immunoassays. Further, the paper offers developers and users a consistent approach to adopting the technology as well as aid in producing accurate and meaningful results.  相似文献   

16.
Newton H 《Medical history》2011,55(2):153-182
Sick children were ubiquitous in early modern England, and yet they have received very little attention from historians. Taking the elusive perspective of the child, this article explores the physical, emotional, and spiritual experience of illness in England between approximately 1580 and 1720. What was it like being ill and suffering pain? How did the young respond emotionally to the anticipation of death? It is argued that children’s experiences were characterised by profound ambivalence: illness could be terrifying and distressing, but also a source of emotional and spiritual fulfilment and joy. This interpretation challenges the common assumption amongst medical historians that the experiences of early modern patients were utterly miserable. It also sheds light on children’s emotional feelings for their parents, a subject often overlooked in the historiography of childhood. The primary sources used in this article include diaries, autobiographies, letters, the biographies of pious children, printed possession cases, doctors’ casebooks, and theological treatises concerning the afterlife.  相似文献   

17.
The preparation steps usually necessary for obtaining ultrathin frozen sections of biological material (chemical prefixation, enclosing, cryoprotective treatment, freezing, sectioning, and post-staining the sections for transmission electron microscopy) are submitted to a critical analysis. The application of cryo-ultramicrotomy, in particularly for cytochemical purposes, is reviewed. Fundamental considerations of chemical prefixation and poststaining are supported by examples from yeast cytology. Furthermore, the efficiency of the cryo-ultramicrotomy (electron optical resolution of ultrastructural details) is demonstrated on yeast cells and protoplasts.  相似文献   

18.
There is a sharp difference in how one views TCR structure–function–behaviour dependent on whether its recognition of major histocompatibility complex‐encoded restriction elements (R) is germline selected or somatically generated. The generally accepted or Standard model is built on the assumption that recognition of R is by the V regions of the αβ TCR, which is not driven by allele specificity, whereas the competing model posits that recognition of R is allele‐specific. The establishing of allele‐specific recognition of R by the TCR would rule out the Standard model and clear the road to a consideration of a competing construct, the Tritope model. Here, the case for allele‐specific recognition (germline selected) is detailed making it obvious that the Standard model is untenable.  相似文献   

19.
Most bodily functions require the coordinated actions of complementary and supplementary paired muscle groups. Where this essential muscular cooperation is lacking, hollow organs may burst and others become literally screwed up, giving rise to many similar spastic diseases such as Torticollis, Twisted ovarian cyst, Torsion of the Testis, Volvulus of the intestines, Varicose Veins, Megacolon, Aortamegaly, Scoliosis, Erb's Palsy, Peyronie's Disease, Main-en-Griffe, Undescended Foot (Pes Cavus), Talipes, Strabismus. Spasm is “panenepidemic” and unclassified examples of Torsion Dystonia and Dyskinesia really are as common as debt and taxes.  相似文献   

20.
Zusammenfassung Die Lagerung des Körpers hat wesentlichen Einfluß auf die Balance der transkapillären Bewegung eiweißarmer Flüssigkeit, das heißt auf das Gesamt-Starling-Gleichgewicht im Kreislauf. Aufrichten aus der horizontalen Lage hat Hämokonzentration, Hinlegen Hämodilution zur Folge. Folglich beeinflußt Lageänderung das Blut- und Plasmavolumen und darüber hinaus Werte wie Eiweißkonzentration, Hämatokrit oder Hämoglobinkonzentration im Blut.In der vorliegenden Arbeit wird die Möglichkeit vorgestellt, mittels der Biegeschwingermethode durch Dichtemessungen an Kapillarblut und -plasma diese orthostatischen Einflüsse auf hämatologische Zustandsvariable zu quantifizieren und ihren zeitlichen Verlauf mit hoher Auflösung zu erfassen.Im Durchschnitt ergab sich infolge Aufrichten des Körpers (70°) aus der Horizontalen eine Verringerung des Plasmavolumens um 6,6% nach 10 und um 11,1% nach 30 min; Hinlegen bewirkte nach 10 min eine Erhöhung des Plasmavolumens um 6,5% und nach 30 min um 10,5%. Entsprechende Blutvolumenveränderungen zwischen 5 und 10% gingen auch aus den Blutdichteänderungen bei orthostatischen Reizen hervor.Eine wichtige praktische Konsequenz ist die Forderung nach Beachtung der Körperlage vor und während Blutabnahmen, vor allem bei Verlaufsmessungen hämatologischer Größen bei ein und demselben Patienten oder bei statistischen Vergleichen verschiedener Kollektive.Diese Arbeit wurde vom Fonds zur Förderung der Wissenschaftlichen Forschung unterstützt  相似文献   

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