中线腰椎融合技术在老年退行性腰椎疾病应用的早期临床疗效及置钉注意事项

目的:探讨中线腰椎融合技术(midline lumbar fusion,MIDLF)治疗老年退行性腰椎疾病的效果、安全性及皮质骨轨迹(cortical bone trajectory,CBT)螺钉固定技术置钉注意事项。方法:回顾性分析我院2018年4月～9月收治的采用MIDLF治疗老年退行性腰椎疾病患者16例,男性8例,女性8例。年龄58～81岁,平均68.7±7.7岁。手术节段均为L4/5。术中均应用CBT螺钉固定技术。入钉点的选择参考上位节段的下关节突最尖端下移约5mm(a值)与峡部最窄处内移约4mm(b值)的交点,记录手术时间、术中出血量、手术并发症等。应用视觉模拟评分法(visual analogue scale,VAS)记录术前和末次随访时腰腿痛情况,应用腰椎JOA评估患者手术后功能改善情况,所有患者出院前及术后12个月均行腰椎CT扫描。通过Rao分级标准评价置钉准确性,置钉优良率=置钉优良数/总置钉数×100%。在术后出院前CT测量螺钉的外倾角、尾倾角、a值和b值。对未突破皮质组与突破皮质组上述4个参数进行比较。结果:手术时间平均174.3±27.9min (133～232min),术中出血量平均69.3±36.7ml(30～150ml),术后总引流量平均147.5±95.2ml(20～315ml),术后住院天数平均2.5±0.8d(2～4d)。术后随访时间平均15.1±2.0个月(12～20个月)。术后1例患者出现足下垂和血肿,有5枚CBT改为椎弓根螺钉固定。其他患者无术中和术后并发症。术前VAS腰痛评分4.5±1.7分,末次随访时为1.1±0.5分,差异有统计学意义(t=7.013,P0.001);术前VAS腿痛评分5.6±1.0分,末次随访时为1.1±0.9分,差异有统计学意义(t=13.006,P0.001);术前腰椎JOA评分15.7±2.4分,末次随访时为23.9±2.1分,差异有统计学意义(t=-16.364,P=0.000)。参考术后出院前CT进行Rao分级:0级46枚,1级4枚,2级3枚,3级6枚。置钉的优良率为84.7%(50/59),突破皮质骨的螺钉有13枚(13/59,22%),其中突破椎弓根内壁的3枚,突破椎体的10枚。未突破皮质骨组与突破皮质骨组比较分析显示螺钉外倾角有显著性差异(11.0°±3.7°vs 14.9°±3.8°,P=0.002),而尾倾角(15.0°±8.4°vs 16.9°±9.2°,P=0.502)、a值(5.6°±1.2°vs 5.7°±1.4°,P=0.687)、b值(4.1°±1.0°vs 4.4°±1.6°,P=0.459)未见显著性差异。结论:MIDLF技术应用于老年退行性腰椎疾病患者时,创伤小,可获得良好的手术效果,入钉点的选择参考上位节段的下关节突最尖端下移5.6～5.7mm(a值)与峡部最窄处内移4.1～4.4mm(b值)的交点,但是CBT螺钉置钉的容错率低,置钉技术要求高,置钉时螺钉外倾不要过大,角度11°为宜。     

Accidental external rotation of distal interlock jig in retrograde femoral nailing can lead to more prominent screws

Objective

Symptomatic distal interlocking screws in retrograde femoral nailing are common due the difficulties of imaging the trapezoidal femur. Screws appearing to have appropriate length on imaging may possibly be prominent, creating symptoms. Screw trajectory may influence the degree of this radiographic error. We hypothesize that external rotation of screw trajectory will increase measurement error of screw length.

Ambulatory activity classification with dendogram-based support vector machine: Application in lower-limb active exoskeleton

Ambulatory activity classification is an active area of research for controlling and monitoring state initiation, termination, and transition in mobility assistive devices such as lower-limb exoskeletons. State transition of lower-limb exoskeletons reported thus far are achieved mostly through the use of manual switches or state machine-based logic. In this paper, we propose a postural activity classifier using a ‘dendogram-based support vector machine’ (DSVM) which can be used to control a lower-limb exoskeleton.A pressure sensor-based wearable insole and two six-axis inertial measurement units (IMU) have been used for recognising two static and seven dynamic postural activities: sit, stand, and sit-to-stand, stand-to-sit, level walk, fast walk, slope walk, stair ascent and stair descent. Most of the ambulatory activities are periodic in nature and have unique patterns of response. The proposed classification algorithm involves the recognition of activity patterns on the basis of the periodic shape of trajectories. Polynomial coefficients extracted from the hip angle trajectory and the centre-of-pressure (CoP) trajectory during an activity cycle are used as features to classify dynamic activities.The novelty of this paper lies in finding suitable instrumentation, developing post-processing techniques, and selecting shape-based features for ambulatory activity classification. The proposed activity classifier is used to identify the activity states of a lower-limb exoskeleton. The DSVM classifier algorithm achieved an overall classification accuracy of 95.2%.     

Novel Risk Factors for Progression of Diabetic and Nondiabetic CKD: Findings From the Chronic Renal Insufficiency Cohort (CRIC) Study

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Depressive symptom trajectories associated with standard and accelerated rTMS

BackgroundTo determine if an accelerated rTMS protocol results in distinct depressive symptom response trajectories, compared to a standard rTMS protocol. We also sought to validate previous analyses that identified distinct depressive symptom response trajectories with rTMS treatment using an external dataset.MethodData from two recent clinical trials comparing accelerated rTMS protocol delivered to the left dorsolateral prefrontal cortex (DLPFC) with standard once-daily rTMS protocol were used to identify depressive symptom response trajectories. The accelerated protocol in Trial 1 was conventional 10-Hz rTMS, while Trial 2 employed intermittent theta burst stimulation (iTBS). Participants were adult outpatients (18–70 years old) with bipolar or unipolar depression and moderate-severe depression (Montgomery Asberg Depression Rating Scale score >19) who had failed to respond to adequate courses of two different antidepressants. We used group-based trajectory modeling to identify MADRS response trajectories, and regression techniques adjusting for baseline depressive symptom severity to determine the association between treatment protocol and depressive symptom response trajectory.ResultsTreatment outcomes of 189 participants were analysed. We identified four distinct response trajectories: “nonresponse” (N = 59; 30.7%), “minimal response” (N = 65; 34.1%), “higher symptoms, response” (N = 26; 14.6%), “lower symptoms, response” (N = 39; 20.6%). We failed to find an association between rTMS protocol (accelerated vs standard) with depressive symptom response trajectory even after adjusting for baseline depressive symptom severity.ConclusionThe accelerated rTMS protocol in this study did not impact depressive symptom response trajectories. This work provides further confirmatory evidence that there are distinct depressive symptom response trajectories with rTMS delivered to the left DLPFC.Australian new zealand clinical trials registryACTRN12616000443493 and ACTRN12613000044729.     

Avoiding iatrogenic vascular injury in tibial external fixation with half pins. An in-vivo study based on CT angiography

BackgroundExternal fixation is an important tool in the management of variety of tibial fractures. Appropriate half pin insertion is important, to provide stable fixation without compromising the surgical field for definitive surgical procedures, and avoiding further damage to the important structures of the traumatized limb. There is paucity of literature about the optimal trajectories and safe corridors for half pins insertion based on in vivo studies. The available studies are based on anatomic atlases, cadaveric studies or half pin related complications.The aim of the current study is to present the findings of CT angiograms, in patients with external fixation of tibia, to enhance our understanding of optimal trajectories in safe corridors for half pins insertion.Material and methodsWe performed a retrospective study of patients with external fixators on the tibia, who had undergone CT angiogram as part of pre-operative planning for orthoplastic reconstructive procedures. The relationship between the tips of the fixator half pins and named vessels of the leg were analyzed, pins within 5 mm of a named vessel were considered to be a risk of causing iatrogenic injury.ResultsA total 51 patients, with in situ temporizing external fixators, with 134 half pins in different segments of the tibia were analyzed. More than 5 mm of penetration beyond the far cortex was noted in 47%, while in another 16% of pins penetration was more than 10 mm beyond the cortex. A tip to vessel distance (TVD) of 5 mm or less was noted in 28/134 (21%) of the pins, which highlights potential risk to the neurovascular bundles of the leg.ConclusionRisk of iatrogenic injury to neurovascular structures from half pin insertion can be reduced by meticulous use of fluoroscopy, by avoiding penetration beyond the far cortex, and avoiding exiting with half pins on the lateral surface in the distal 1/3rd of segment II of tibia. Moreover observing optimal trajectories and safe corridors for pin insertion, and selection of appropriate type of half pin can mitigate the risk to these structures.