后纵韧带生物力学测试评价胸腰段脊柱前路减压后的稳定性

背景：到目前为止,对于后纵韧带在胸腰段脊柱前路减压术式中所发挥的生物力学稳定作用的研究未见文献报道。 目的：通过生物力学测试,评价胸腰段脊柱后纵韧带在椎管前方减压自体髂骨植骨+Kaneda内固定过程中的作用。 方法：采用7具新鲜小牛胸腰段脊柱(T₁₁~L₃)标本,采用前后对照方法,按操作过程标记为：正常组→后纵韧带完整组(椎管前方减压植骨内固定,保留后纵韧带组)→后纵韧带切除组,应用实验应力方法测试各组的生物力学特性。模拟临床手术行L₁椎体切除椎管前方减压自体髂骨植骨+Kaneda内固定,在脊柱WE-10A万能材料实验机上进行非破坏性生物力学测试,并计算应变、刚度、轴向压缩强度、扭转强刚度等数据,通过F检验分析数据。 结果与结论：胸腰椎椎管前方减压植骨+Kaneda内固定,局部切除后纵韧带使胸腰椎的稳定性在旋转、轴压、前屈、后伸、侧弯各运动状态下降,其中以前屈时最为明显,差异具有显著性意义(P < 0.05)。提示在胸腰段脊柱椎管前方减压过程中,局部切除后纵韧带将使术后脊柱稳定性在前屈状态时下降,不利于提高脊柱的融合率。因此应尽可能保留正常的后纵韧带。     

保留前纵韧带的椎体间植骨术的稳定性实验研究

目的：为评价保留前纵韧带的椎体间支撑植骨治疗脊柱爆裂骨折提供的生物力学稳定能力。方法：用传感器及电测技术，采用新鲜人体胸腰段脊柱标本。结果：除旋转外，轴压、前屈、后伸、侧弯四种运动方式皆能提供满意的稳定性。结论：实验提示，该方法能明显增加损伤脊柱的力学稳定性，有利于提高脊柱的融合率，是一种治疗脊柱骨折较为理想的植骨方法     

后路钉棒系统置入内固定并侧前方减压植骨融合治疗胸腰椎严重爆裂骨折12例

背景：胸腰椎爆裂性骨折侧前方减压植骨融合、钉棒系统内固定术可通过同一切口实现。 目的：观察后路钉棒系统置入内固定并侧前方减压植骨融合治疗胸腰椎严重爆裂骨折合并脊髓及神经根损伤的临床疗效。 方法：回顾采用后路钉棒系统置入内固定,侧前方减压植骨融合治疗12 例胸腰椎爆裂骨折合并神经损伤的病例。 结果与结论：12例患者椎管均获得有效减压,均随访9个月以上。影像学显示植骨块融合良好, 伤椎高度基本恢复,Cobb’s 角由术前平均22°恢复到6°,F rankel 分级恢复1级者6 例,恢复2级者3 例,无变化者3例。结果表明,采用后路钉棒系统内固定加侧前方减压椎体次全切除植骨融合是集减压、复位、内固定、植骨融合、矫正畸形、重建脊柱稳定一次完成的有效方法,但应严格掌握适应证。     

一期前后联合入路治疗胸腰段脊柱结核

目的探讨前路一期结核病灶清除植骨融合联合后路钉棒系统内固定治疗胸腰段椎体结核的疗效。方法 2007年2月～2009年10月手术治疗胸腰段椎体结核13例,均采用前路一期结核病灶清除取自体髂骨植骨融合联合后路钉棒系统内固定治疗胸腰段椎体结核,根据术前、术后X线平片分析植骨融合及术后畸形矫正效果。结果经6～18个月随访,脊髓神经功能得到不同程度的恢复,植骨融合满意,无内固定失败和脊柱结核病灶复发。结论前路一期结核病灶清除植骨融合联合后路钉棒系统内固定治疗胸腰段椎体结核具有椎管减压彻底,脊柱后凸侧弯畸形易于矫正,内固定远离病灶处等特点,是治疗胸腰段椎体结核的一种有效手术治疗方法。其缺点是手术创伤相对较大[1],术中操作相对繁琐。     

脊髓前路减压Kaneda器械内固定治疗胸腰段脊柱损伤伴截瘫

目的探讨胸腰段脊柱损伤伴截瘫患者前路手术及Kaneda器械内固定方法。方法总结20例患者经前路减压及Kaneda器械内固定治疗脊柱损伤伴截瘫的经验。结果20例患者经治疗后，5例不全瘫及3例截瘫患者下肢肌力恢复正常，能下地行走，其余12例患者下肢肌力感觉无明显改善。结论脊髓前路减压可减除脊髓前方压迫，为神经功能的保护或恢复创造了必要条件，而Kaneda器械内固定可早期重建脊柱的稳定性。     

后路间接减压植入物内固定与后路椎板切除直视下减压内固定治疗胸腰椎爆裂骨折

背景：对于后纵韧带复合体完整的胸腰椎爆裂骨折是否需要减压,采用何种复位效果较为可靠,尚缺乏临床对照研究。 目的：对比后路间接减压植入物内固定与后路椎板切除直视下减压内固定治疗后纵韧带复合体完整的后柱牵张性损伤胸腰椎爆裂骨折的临床效果。 方法：纳入后纵韧带复合体完整的后柱牵张性损伤胸腰椎爆裂骨折患者48例,其中23例采用后路间接减压植入物内固定修复,25例采用后路椎板切除直视下减压内固定修复。观察固定后并发症、脊柱后凸畸形矫正情况、椎管占位复位和神经损伤恢复程度。 结果与结论：所有患者随访20~25个月,随访期间,采用后路间接减压植入物内固定修复患者的早期并发症发生率、远期残留背痛及活动受限的发生率均低于采用后路椎板切除直视下减压内固定修复的患者;固定后1周,后路间接减压植入物内固定后椎体前后缘高度、Cobb角纠正程度优于后路椎板切除直视下减压内固定,固定后1年,两组患者脊柱后凸畸形纠正程度、神经损伤恢复情况差异无显著意义。说明对于后纵韧带复合体完整的后柱牵张性损伤胸腰椎爆裂骨折应优选后路间接减压植入物内固定进行修复。     

前路减压植骨内固定在基层医院胸腰椎骨折伴脊髓损伤治疗中的应用

目的探索在基层医院对胸腰椎爆裂骨折伴脊髓损伤行前路减压,植骨内固定的治疗效果。方法 36例胸腰椎骨折伴脊髓损伤行前路减压,Kaneda器械固定8例,Z-Plate钢板系统固定28例。结果随访6个月~4年,治疗后胸腰段脊柱生理曲度基本恢复,内固定无松动和断裂,植骨融合好,神经功能恢复(按Frankel分级)。总有效率为89%,完全恢复正常为25%。结论在基层医院,对胸腰椎骨折伴脊髓损伤行前路减压,植骨融合内固定治疗,取得较好的疗效和一定的社会和经济效益。     

椎弓根螺钉置入内固定与单纯椎管减压治疗退行性腰椎滑脱的比较

背景：随着脊柱内固定和脊柱融合技术的发展,脊柱融合已成为腰椎退行性滑脱症毫无争议的“金标准”。同时,邻近节段退行性变的问题引起人们越来越多的关注。 目的：观察椎弓根螺钉内固定置入植骨融合治疗退行性腰椎滑脱的临床疗效、手术节段稳定性及其对相邻节段的影响,并与单纯椎管加压进行对比。 方法：选择天津医科大学总医院骨科收治的退行性腰椎滑脱患者38例,排除失访3例,余35例中采用椎弓根固定后外侧融合21例,单纯椎管减压14例。单纯椎管加压组用咬骨钳咬除黄韧带和椎板解除神经根后方的压迫,用骨凿凿除向前滑脱的椎体后缘与下位相邻椎体后缘形成的相对性突起;椎弓根螺钉固定植骨融合组按Wein-stein 法定位椎弓根钉进针,拧入椎弓根螺钉,根据受压情况进行椎板减压。按Oswestry功能障碍指数综合评价临床疗效,观察过伸、过屈位时的水平位移及角移位,采用UCLA系统来评价邻近节段退变情况。 结果与结论：35例患者随访时间1年。椎弓根螺钉固定植骨融合组优良率显著高于单纯椎管加压组(P < 0.05)。椎弓根螺钉固定植骨融合对腰椎稳定性影响不大,邻近节段退变置入前和置入后1年无明显变化。单纯椎管加压对腰椎稳定性影响显著,同时治疗前和治疗后1年邻近节段退变无明显变化。提示椎弓根螺钉内固定置入植骨融合治疗退行性腰椎滑脱疗效满意,对腰椎稳定性影响小,并且置入后早期对椎间盘的邻近节段影响不大。     

前路减压植骨内固定治疗胸腰椎骨折

目的:探讨胸腰椎骨折的前路减压植骨内固定的临床疗效.方法:采用前路减压自体髂骨植骨内固定术治疗胸腰椎骨折14例,其中10例合并不全瘫.结果:术后随访3个月～2 a,平均1 a,14例病人脊柱畸形矫正满意,生理曲度恢复,植骨均达到骨性融合.10例术前有脊髓功能损伤患者术后有1～3级的神经功能恢复,无内固定松动、断钉、断板等发生.结论:前路手术安全可靠,椎管减压彻底,可重建脊柱的稳定性,恢复脊柱的生理曲度.     

后纵韧带对椎体爆裂骨折椎骨内骨块复位作用的生物力学行为特性及其临床意义探讨

目的：观测脊柱后纵韧带（PLL）对椎体爆裂骨折突入椎管骨块前推复合力的生物力学行为特点。方法：取人体脊柱标本制作爆裂骨折损伤模型,以测力探头测试不同脊柱状态下PLL对突入椎管骨块的前推复位力。结果：在撑开力（140N）作用下PLL前推复位力明显增加,无撑开力作用时后伸状态PLL前推复位力大于前屈状态,撑开后伸时PLL前推力与撑开前屈无显著差异,PLL前推力与骨块占位程度成正相关。结论：撑开力是PLL对骨块间接复位作用的决定性因素,脊柱前屈后伸状态及骨块占位程度也是影响因素。在治疗胸腰椎爆裂骨折中要获得椎管内骨块的间接复位减压,使用具有较强撑开能力的内固定装置进行纵向撑开是最重要的。     

Intergenerational stability of the myotonic dystrophy protomutation

The amplification of the CTG trinucleotide repeat in myotonicdystrophy (DM) correlates with increasingly severe phenotypes.We designate its minimal amplification the ‘protomutation’since it is the mutation itself at an early stage of intergenerationalevolution and is associated with very mild clinical signs. Fromthe study of 536 DM mutation carriers (from 158 affected families),a total of 60 DM-parent/DM-offspring pairings were identifiedin which the parent had the protomutation. We found a strongcorrelation between the protomutation length and the amplificationobserved in the next generation. We also observed the stabletransmission of the protomutation through successive generations.This stability may explain the maintenance in the populationof this autosomal dominant disease despite the low reproductivefitness of severe DM phenotypes.     

Internal deletion compromises the stability of dystrophin

Duchenne muscular dystrophy (DMD) is a deadly and common childhood disease caused by mutations that disrupt dystrophin protein expression. Several miniaturized dystrophin/utrophin constructs are utilized for gene therapy, and while these constructs have shown promise in mouse models, the functional integrity of these proteins is not well described. Here, we compare the biophysical properties of full-length dystrophin and utrophin with therapeutically relevant miniaturized constructs using an insect cell expression system. Full-length utrophin, like dystrophin, displayed a highly cooperative melting transition well above 37°C. Utrophin constructs involving N-terminal, C-terminal or internal deletions were remarkably stable, showing cooperative melting transitions identical to full-length utrophin. In contrast, large dystrophin deletions from either the N- or C-terminus exhibited variable stability, as evidenced by melting transitions that differed by 20°C. Most importantly, deletions in the large central rod domain of dystrophin resulted in a loss of cooperative unfolding with increased propensity for aggregation. Our results suggest that the functionality of dystrophin therapeutics based on mini- or micro-constructs may be compromised by the presence of non-native protein junctions that result in protein misfolding, instability and aggregation.     

Temporal stability of the emotion-modulated startle response

In the present study, we examined the stability of one measure of emotion, the emotion-modulated acoustic startle response, in an undergraduate sample. Using the acoustic startle paradigm on two different occasions, we measured stability of affective modulation of the startle response during and following the presentation of pictures selected to be of positive, negative, or neutral emotional valence. The two assessments were separated by 4 weeks. Two groups of subjects were compared: one group that viewed the same pictures at each assessment and a second group that viewed different pictures at the second assessment. We found that viewing different pictures at two assessments separated by 4 weeks yielded moderate stability of the emotion modulation of startle magnitude, whereas subjects who viewed the same pictures at both assessments showed poor stability. Furthermore, this difference was due to the stability of responses to high versus low arousal pictures, not to differences in valence.     

Chemical control stability in the elderly

The prevalence of central apnoea and periodic breathing is increased in the elderly. This implies that the chemical control of breathing might become less stable with ageing. To investigate this, we measured loop gain in healthy elderly individuals using proportional assist ventilation. Loop gain is an engineering term that describes the stability of a system controlled by feedback loops, such as the respiratory control system. A loop gain close to zero indicates a stable system, whereas a loop gain close to or greater than one indicates an unstable system. Eleven healthy elderly subjects were studied with a mean ± s.d. age and body mass index (BMI) of 71 ± 5 years and 25 ± 3 kg m⁻², respectively. We also studied a small group of elderly individuals with obstructive sleep apnoea (OSA) for comparison ( n = 3, age 68 ± 1 years, BMI 32 ± 11 kg m⁻²). Comparisons were made with previously studied young individuals (age 27 ± 4 years, BMI 23 ± 1 kg m⁻²). We found significantly lower loop gains in the healthy elderly group (loop gain ≤ 0.25) compared with the young group (loop gain ≤ 0.47, P = 0.001). Also, we found quite low loop gains in the elderly OSA group (loop gain ≤ 0.26). We conclude that the chemical control of breathing does not become unstable with ageing and is thus an unlikely cause of central (and possibly obstructive) apnoeas in this population.     

Temporal stability of the hemodynamics of cardiovascular reactivity

Cardiovascular responses to a competitive reaction-time task were monitored in 13 male subjects tested twice, 3 months apart. The temporal stability of blood pressure responses was in line with previous reports. However, in this study impedance cardiography permitted the investigation of the hemodynamic adjustments underlying the observed blood pressure responses. Analyses revealed that cardiac output and total peripheral resistance responses displayed temporal stability, indicating that subjects' blood pressure responses on the two occasions were the result of similar hemodynamic responses. These data thus extend the literature by demonstrating that the hemodynamic response pattern itself represents a stable individual difference variable.