Post-retrieval functionality testing of PRECICE lengthening nails: The “Sleeper” nail concept

IntroductionPRECICE intramedullary magnetic lengthening nails, introduced in 2011, have changed the landscape of long bone limb lengthening. The implants have a stroke ranging from 5 to 8 cm, but it may be desirable to perform part of the lengthening at one treatment, allow bone healing, leave the implant in place, dormant, and then return one or more years later to re-lengthen with the same implant. We call this the “sleeper” nail concept. This strategy may be gentler for the joints and soft tissues. Would the nail mechanism still be functional one or more years later?MethodsWe tested 102 intact, consecutively explanted nails. Using a “fast magnet,” the male part was lengthened to 5 mm short of its maximum stroke capacity and retracted back to 35 mm (all nails start with the male part exposed 30 mm). The nails passed the test if the male part succeeded in lengthening to 5 mm short of the maximum stroke capacity and back to 35 mm (or only retract in case fully deployed at testing). During our testing, the nails were prevented from reaching their full capacity of lengthening/retraction to avoid jamming the gears. Failure was defined as the inability or partial ability to complete the process.ResultsEighty-six nails (84.3%) performed successfully according to our testing standard. When comparing successful and failed nails in terms of nail type, generation, diameter, length and in vivo interval, there was no statistical significance. Comparing both groups in terms of status at testing (fully deployed or not) showed statistical significance with 9 of the 16 failed nails fully deployed at testing (p < 0.001).ConclusionDormant PRECICE nails can be reactivated for further lengthening. The results imply that full deployment may damage the mechanism, making future re-use by retracting and then re-lengthening unsuccessful. The candidate nails for this purpose should not have any signs of clear damage (bending or breakage) and should not have been fully deployed. However, surgeons and patients should be aware of the need for possible nail exchange if the “sleeper” nail fails to wake up.Level of evidenceLevel IV case series analysis of retrieved surgical implants.     

提高脊柱骨折水平复位力量对Harrington分离棒应力分布的影响——二维光弹性实验研究

使用Edwards套棒可提高Harrington装置对脊柱骨折的解剖复位率,但同时使Harrington棒各点应力值呈线性增加,尤以套棒所在点受影响最大,然而总体应力分布趋势不变,棒体——齿棘区交界处应力集中为棒的危险断面,棒前侧应力值高于后侧;齿棘部高于棒体部。实验结果提示,临床应用Ebwards套捧时应注意将其安置在尽量远离危险断面处,并使危险断面尽量靠近上钩,以减少在交变应力作用下应力集中造成的Harrington棒疲劳断裂。     

脊柱侧凸矫形钽氏棒内固定失败原因分析

目的：分析脊柱侧凸鲁氏棒矫形内固定术后内失败的原因,为今后应用鲁氏棒治疗脊柱侧凸提供有益的借鉴。方法回顾1989年1月至1999年3月收治的脊柱侧凸患者应用鲁氏棒矫形内固定者96例,其中由各种原因所致的内固定失败者15例。结果：分析造成内固定失败的原因为①术前软组织松解不充分;②矫形过程中拧紧内固定钢丝时用力不均匀;③内固定钢丝数量太少;④植骨的数量不足;⑤内固定的节段不正确;⑥下床活动太早。结论：应用鲁氏棒治疗脊柱侧凸仍然是一种行之有效的方法,但在术前准备、手术过程和术后处理时,应注意以上可能造成固定失败的因素。     

老年性黄斑变性的黄斑部光敏感度检测

目的　探讨老年性黄斑变性早期患者黄斑暗视敏感度的变化。方法　用Octopus10 1型视野计 ,对早期老年性黄斑变性组 2 0例 30眼 ,对照组正常人 2 1例 2 6眼进行暗视和明视敏感度检测 ,应用tM2 测试程序 ,将中心 30°视野内视网膜暗视和明视敏感度进行比较和分析。结果　老年性黄斑变性组暗视和明视敏感度较正常组均降低 ,且暗视敏感度降低值大于明视敏感度降低值 ,差异显著 (P <0 .0 5 )。结论黄斑暗视敏感度检测可作为老年性黄斑变性早期诊断和检测指标。     

A robust and real-time vascular intervention simulation based on Kirchhoff elastic rod

A virtual reality (VR) based vascular intervention simulation system is introduced in this paper, which helps trainees develop surgical skills and experience complications in safety remote from patients. The system simulates interventional radiology procedures, in which flexible tipped guidewires are employed to advance diagnostic or therapeutic catheters into vascular anatomy of a patient. A real-time physically-based modeling approach ground on Kirchhoff elastic rod is proposed to simulate complicated behaviors of guidewires and catheters. The slender body of guidewire and catheter is modeled using more efficient special case of naturally straight, isotropic Kirchhoff rods, and the shorter flexible tip composed of straight or angled design is modeled using more complex generalized Kirchhoff rods. The motion equations for guidewire and catheter were derived with continuous elastic energy, followed by a discretization using a linear implicit scheme that guarantees stability and robustness. In addition, we used a fast-projection method to enforce the inextensibility of guidewire and catheter. An adaptive sampling algorithm was also implemented to improve the simulation efficiency without decrease of accuracy. Experimental results revealed that our system is both robust and efficient in a real-time performance.     

生活垃圾集装箱在集装化转运系统中的改进技术研究

为延长生活垃圾集装箱及其零配件的使用寿命,以及解决箱门无法正常开闭和在运输途中的垃圾渗沥液渗漏问题,对部分零部件(扇齿轮、水平杆、兼容箱箱门门框密封技术)进行了技术革新,有效缓解了现存的问题.     

AIS患者主侧凸及总体侧凸向量对躯干冠状面平衡的影响

目的探究青少年特发性脊柱侧凸（AIS）患者主侧凸向量、总体侧凸向量对手术前后躯干冠状面平衡(CTB)的影响。方法回顾性分析22例采用后路椎弓根钉-棒系统矫形治疗的AIS患者的临床资料。所有患者术前、术后均摄站立位脊柱全长正侧位X片,术前拍摄仰卧位左右Bending像。引入物理中表示大小和方向的向量概念,对术前和术后末次随访时冠状面C7铅垂线（C7PL）相对于骶骨中垂线(CSVL)的偏移情况、冠状面各个侧凸的向量等参数进行统计分析。结果术前C7PL-CSVL向量与术前主侧凸向量相关性有统计学意义（r=0.447,P<0.05）,术前C7PL-CSVL向量与术前所有侧凸向量之和的相关性有统计学意义（r=0.510,P<0.01）。主侧凸校正量与C7PL-CSVL变化量的相关性无统计学意义（P＞0.05）,主侧凸校正率与C7PL-CSVL变化率的相关性无统计学意义（P＞0.05）。C7PL-CSVL大小与主侧凸cobb角大小、所有侧凸cobb角大小之和的相关性无统计学意义（P＞0.05）。结论干预（支具、手术）AIS患者可能出现的躯干冠状面失平衡的重点应该是防止躯干整体向主侧凸和总体侧凸的凸出方向偏移。手术前后AIS患者侧凸cobb角与CTB无直接关系。     

生长棒撑开术中经颅刺激运动诱发电位和体感诱发电位监测的应用价值

目的:分析生长棒撑开术中经颅刺激运动诱发电位(MEP)和体感诱发电位(SEP)神经功能监测的应用价值。方法:回顾性分析2010年10月~2015年1月我院进行的65例141次生长棒撑开手术,在生长棒撑开术中,运用MEP和SEP进行神经功能监测。MEP监测采用经颅刺激C3、C4,记录外周肌源性MEP,SEP监测采用刺激双侧胫后神经,记录电极采用Cz-CPz。阳性诊断标准:与基线相比,MEP波幅下降75%,SEP波幅下降50%或潜伏期延长10%。结果:141例次撑开手术中成功获得具有监护价值且重复性较好MEP 139例次,检出率98.6%,全程失败2例次(占1.4%);SEP成功监测140例次,检出率99.3%,失败1例(占0.7%)。所有患者均能成功记录到一种以上的诱发电位。本组141例次手术中未出现MEP及SEP监测阳性。所有患儿术后神经系统检查均无异常发现,神经功能监测结果均为真阴性。结论:生长棒撑开术是简单安全的手术操作,但是,运用MEP和SEP进行术中神经功能监测可以为生长棒撑开术提供客观的安全评估指标。     

Correcting QUEST Magnetic Resonance Imaging–Sensitive Free Radical Production in the Outer Retina In Vivo Does Not Correct Reduced Visual Performance in 24-Month-Old C57BL/6J Mice

PurposeTo test the hypothesis that acutely correcting a sustained presence of outer retina free radicals measured in vivo in 24-month-old mice corrects their reduced visual performance.MethodsMale C57BL/6J mice two and 24 months old were noninvasively evaluated for unremitted production of paramagnetic free radicals based on whether 1/T1 in retinal laminae are reduced after acute antioxidant administration (QUEnch-assiSTed [QUEST] magnetic resonance imaging [MRI]). Superoxide production was measured in freshly excised retina (lucigenin assay). Combining acute antioxidant administration with optical coherence tomography (i.e., QUEST OCT) tested for excessive free radical–induced shrinkage of the subretinal space volume. Combining antioxidant administration with optokinetic tracking tested for a contribution of uncontrolled free radical production to cone-based visual performance declines.ResultsAt two months, antioxidants had no effect on 1/T1 in vivo in any retinal layer. At 24 months, antioxidants reduced 1/T1 only in superior outer retina. No age-related change in retinal superoxide production was measured ex vivo, suggesting that free radical species other than superoxide contributed to the positive QUEST MRI signal at 24 months. Also, subretinal space volume did not show evidence for age-related shrinkage and was unresponsive to antioxidants. Finally, visual performance declined with age and was not restored by antioxidants that were effective per QUEST MRI.ConclusionsAn ongoing uncontrolled production of outer retina free radicals as measured in vivo in 24 mo C57BL/6J mice appears to be insufficient to explain reductions in visual performance.