聚乙烯醇水凝胶髓核的生物力学特性

目的 对一种新型水凝胶人工髓核的生物力学特性进行研究,为将来临床开展人工髓核置换手术提供科学依据。方法 采用7具新鲜标本的L_(4-5)脊柱功能单元进行生物力学实验,在轴向压缩、前屈后伸和左右侧弯等运动工况下,观察正常椎间盘、髓核摘除以及人工髓核植入3种状态下椎间盘高度、应变和位移的变化。结果 与正常椎间盘相比较,髓核摘除后椎间盘的高度和刚度降低,应变和位移加大(P<0.05)。而人工髓核植入后各项指标恢复正常(P>0.05)。结论 这种新型水凝胶人工髓核置换可纠正髓核摘除后的生物力学紊乱,有望进行临床应用。     

青年性腰椎弓根崩裂直接修复后TSRH钩钉系统固定12例初步报告

[目的]评价TSRH钩钉系统对青年患者腰椎弓崩裂直接修复后固定的临床疗效。[方法]自2001年7月~2003年10月,对12例男性单纯腰椎弓崩裂患者(16~31周岁)行腰椎弓崩裂自体骨直接修复峡部裂后TSRH椎板钩、椎弓根钉固定术。术后随访,根据术后X线、CT结果评价修复效果,并根据MacNab's标准进行临床评价。[结果]经过6~19个月随访,所有患者腰椎弓崩裂影像学全部融合;临床下腰痛显著缓解,按MacNab's标准,优8例,良3例,一般1例;无手术及内固定相关并发症发生。[结论]直接修复后TSRH钩钉系统固定治疗青年性腰椎弓崩裂能充分保留腰椎运动节段,在减少融合节段的同时能有效恢复腰椎稳定,操作简便、安全,固定可靠,是一种合乎逻辑的治疗青年性腰椎弓崩裂方法。     

动态颈神经根管率的X线片测量

目的　应用新的颈椎斜位X线片测量方法测量颈神经根管矢状径、动态颈神经根管矢状径率 ,确定诊断神经根管狭窄敏感指标。方法　取 2 0 0名不同年龄段的成人摄取颈椎动态斜位X线片 (斜位、过伸斜位、过屈斜位 ) ,测量动态神经根管的矢状径 (a )、椎体斜位矢状径 (b )、计算颈神经根管率 (a/b )。分年龄、性别及组别进行统计分析。结果　①同一节段不同年龄、不同性别颈神经根管率差异无统计学意义。②不同组别动态颈神经根管率差异有非常显著性 (P <0 .0 1)。结论　①动态神经根管率是诊断神经根型颈椎病有效和敏感指标。②颈椎动态神经根管率 95 %理想值范围底限为 0 .30。颈椎动态神经根管率≤ 0 .30时应考虑颈神经根管狭窄     

Etiological musculo-skeletal factor in focal dystonia in a musician's hand: A case study of the right hand of a guitarist.

A case study is presented in which a focal hand dystonia seems to have developed in the right hand of a classical guitarist as a result of a neuromuscular peripheral defect caused by trauma. The trauma was a near total perforation of the first web space by a splinter. Healing was uneventful without apparent functional complications. Two years later the patient noticed difficulties in extending the index in playing, for which he received various unsuccessful treatments during seven years. However, we found more severe dystonic symptoms (cocontractions) in the thumb than in the index during playing, which correlated with an undiagnosed insufficiency in the flexor pollicis brevis (FPB). This defect allowed proposing a biomechanical analysis of compensations for diminished thumb control in playing, which would explain the dysfunction in the index in playing as overcompensation for the thumb problem. If this analysis is correct, the etiology of the case can be traced back to underlying multiarticular control problems in the thumb caused by an insufficient FPB. This defect was considered irrepairable. It was concluded that even with knowledge of the underlying cause, a potentially successful treatment of the dystonia might not exist in this case. The case would demonstrate that task-specific hand dystonias can arise as overcompensations for (peripheral) neuro-musculoskeletal defects. The case is illustrated by videos of playing and functional thumb tests.     

Why do long-distance runners not have more bone? A vital biomechanical explanation and an estrogen effect

Inanimate structures cannot detect and repair their fatigue damage or microdamage, so to minimize it they need more structural material and strength. Living bone handles this matter differently. Bone modeling drifts adapt bone architecture and strength to the loads on bones in ways that tend to keep strains from exceeding a “modeling threshold” range. Strains (or equivalent features) above that threshold switch mechanically controlled modeling ON. Where strains stay below that threshold, this modeling goes OFF. Repeatedly loading-deloading a bone causes microdamage in it, and basic multicellular unit (BMU)-based bone remodeling normally repairs it. Where strains stay below an operational “microdamage threshold,” remodeling can repair whatever microdamage happens for as long as it happens. Strains above that threshold can cause too much microdamage to repair completely and lead to fatigue fractures of trabeculae or whole bones. The modeling threshold normally lies comforably below the microdamage threshold. Since modeling normally adjusts bone architecture to keep strains from exceeding the modeling threshold, this keeps strains below the microdamage threshold, too, and voluntary activities do not cause more microdamage than remodeling can repair. Therefore, long-distance runners do not need more bone mass and strength than nonrunners of comparable age, sex, and body size.     

应用三维有限元模型研究颈椎不同工况下的生物力学变化

目的 研究颈椎前屈、后伸、侧屈、旋转等多种工况下，钩椎关节、小关节应力规律，从应力角度探讨钩椎关节、小关节退变的生物力学机制。方法 测量尸体颈段脊柱各节点三维坐标，利用SUPER—SAP软件建立机内模型，模拟完整的颈段脊柱力学模型。通过测量求得力矩值，直接或根据力矩等价公式间接将肌力值加载于模型体表各点。运用颈椎周围不同肌肉对颈椎作用力的变化，模拟正常活动范围内颈椎前屈、后伸、侧屈、旋转等多种工况。分别计算并得出相应载荷下钩椎关节、小关节应力值。结果钩椎关节在各种工况下的受力总体上集中于颈椎中下段。前屈时，由上至下呈现逐渐增大趋势；后伸时，在C4-5，C5-6出现应力集中现象。小关节各种工况下的受力状况总体趋势与钩椎关节相同，前屈时z轴上受到拉应力，后伸时受到压应力，且后伸时承受的拉应力是前屈时承受压应力的2倍多。这说明小关节在后伸时起到承受和传导载荷的作用。结论 不同运动状态下，中下段颈椎的钩椎关节、小关节出现应力集中。     

In vivo measurement of the shear modulus of the human vocal fold: interim results from eight patients

The shear modulus of the vocal fold is an essential parameter required to enhance our understanding of how the vocal fold operates, to develop mathematical models of phonatation, and to provide benchmarks to quantify the effectiveness of surgical procedures. The authors announced the successful deployment of an instrument to measure vocal fold elasticity in vivo last year, and now present the data taken from eight patients in vivo. The shear modulus was measured at the mid-membranous point, in a transverse direction with respect to the axis drawn between the anterior commissure and vocal process. The range of mean shear modulus results is 701–2,225 Pa, with a mean value of 1,371 Pa.     

小牛胸腰椎解剖、生物力学研究及其临床意义

目的　测量小牛胸腰椎相关解剖数据并测试其生物力学性能 ,探讨其作为胸腰椎前路内固定模型的可行性。方法　采集 1周以内的新鲜小牛胸腰椎脊柱标本 2 0具 ,测量椎体及椎间盘的最大横径、矢状径和前部高度。测试屈曲、伸展、侧屈及扭转状态下的载荷 -应变、载荷 -位移关系以及最大载荷时的应力强度及轴向刚度 ,并进行极限力学性能测试。结果　小牛胸腰椎椎体及椎间盘矢径、横径、高度自T10 至L5逐渐递增 ,椎体横径与矢径之比约为 1∶1,其T10 ～L5段椎间盘高度之和与椎体高度比值为 1∶0 .9。小牛胸腰椎载荷 -应变及载荷 -位移关系呈线性变化 ,生理载荷下屈曲、伸展及侧屈状态下的应力强度分别为 (2 .86± 0 .2 4 )N/mm2 ,(2 .17± 0 .2 0 )N/mm2 ,(5 .2 9± 0 .5 0 )N/mm2 。屈曲、伸展、侧屈及扭转状态下的轴向刚度分别为 (37.13± 4 .30 )N/mm ,(35 .38± 4 .2 0 )N/mm ,(34.5 6± 4 .2 0 )N/mm ,(5 1.6 9± 1.6 2 )N/mm。结论　小牛胸腰椎形态及大小可满足前路内固定模型的需要 ,以小牛标本作为体外非破坏性生物力学实验模型具有可行性。     

人正常下颌升支区应力分布的三维有限元法分析

目的：对正常人下颌升支在不同咀嚼力作用时应力分布情况进行三维有限元分析。方法：采用三维有限元应力分析的方法，对正常离体人下颌升支在不同加载条件下的应力分布特征进行对比定量分析。结果：(1)所有载荷形式的各种应力值，随着单元距加载点的距离的增大，其应力值相对减小。(2)下颌骨下颌角、升支后缘的应力梯度变化较大。结论：下颌骨下颌角、升支后缘是应力相对集中的区域，也是临床上常见的下颌骨骨折区，同时还是下颌升支矢状骨劈开术后加强固定以及防止骨段移位的区域。     

Effect of pulley integrity on excursions and work of flexion in healing flexor tendons

Effect of pulley integrity on excursions and work of flexion in healing flexor tendons@Wang YH @Gu YT @Chen F