Dynesys在腰椎退变性疾病治疗中的应用进展

Dynesys（dynamic neutralization system,Dynesys）是一种后路经椎弓根动态内固定装置,由Stoll等[1]在Graf韧带系统的基础上改进设计而成,是目前临床上使用较为广泛的非融合内固定方式之一。其设计目的在于维持手术节段稳定性的同时保留一定的椎体间活动度（range of motion,ROM）,以减缓邻近节段退变（adjacent segments degeneration,ASD）的发生。Dynesys自应用于临床以来已有十几年的历史,现已广泛用于腰椎间盘突出症、腰椎管狭窄症、退行性脊柱侧凸和腰椎滑脱症等腰椎退变性疾病行减压术后的辅助治疗。其适应证包括[2]：①腰椎管狭窄或退行性腰椎滑脱所导致的神经源性疼痛或椎间盘退变所导致的腰背痛;②减压手术导致的医源性腰椎不稳;③退行性脊柱侧凸所致的椎管狭窄并处于进展期。禁忌证：①Ⅱ度以上的峡部不连性或退行性椎体滑脱;②大于10°的退行性脊柱侧凸;③颈、胸椎;④局部有骨肿瘤、感染或骨折;⑤合并重度骨质疏松及其他代谢性骨疾病;⑥融合失败后的翻修术;⑦严重椎间盘退变导致的椎间盘源性疼痛。现就Dynesys的临床应用进展综述如下。     

Dynesys动态稳定系统治疗下腰椎疾病效果观察

 目的 探讨Dynesys动态稳定系统治疗腰椎退行性疾病的应用指征及安全性。方法 回顾性分析2007 年1 月至2011 年12 月采用后路减压+Dynesys动态内固定系统治疗102例腰椎退行性疾病患者中69例完整的随访资料,男39例,女30例;年龄30~62岁,平均44岁;单纯腰椎间盘突出24例,腰椎间盘突出并退行性椎管狭窄35例,椎间盘退行性改变10例。手术固定节段: L_2,3 2例,L_3,4 4例,L_4,5 42例,L₅S₁15例,L₃~L₅ 5例,T₁₂~L₄ 1例。采用视觉模拟评分(visual analogue scale,VAS)评估疼痛;临床疗效评价采用Oswestry功能障碍指数(Oswestry disability index,ODI)。结果 手术时间为1.5~4.2 h,平均2.5 h;术中出血80~550 ml,平均320 ml。术后随访时间为6~44 个月,平均35个月。VAS评分,术前6~9分,平均8.6分;术后0~5分,平均2.8分。术前ODI为30%~91%,平均73%;术后为0~61%,平均30%。无一例发生钉绳系统和聚酯套管松动及深部感染。术后根据中华医学会骨科学分会脊柱学组腰背痛手术评定标准对手术疗效进行评价,优53 例,良12 例,可4 例,优良率为94.2%(65/69)。结论 Dynesys动态内固定系统能在保留腰椎手术节段活动度的同时保证术后临床症状恢复,是治疗腰椎退行性疾病的一种有效的非融合性、动力性固定方法。     

Dynesys动态固定系统治疗腰椎退变性疾病的临床疗效

目的探讨Dynesys动态固定系统应用于退变性腰椎疾病中的临床疗效评价。方法自2009-01—2013—01采用Dynesys动态固定系统结合后路椎板减压治疗35例腰椎退变性疾病,包括腰椎间盘突出症23例,腰椎管狭窄症12例。结果术后随访时间为6-40个月。平均26个月。术后3个月、1年和末次随访时的VAS及ODI均较术前明显下降。差异有统计学意义（P〈O．05）,而末次随访时较术后3个月和1年继续下降,差异有统计学意义（P〈0．05）。手术节段椎间隙后缘高度较术前明显增加,差异有统计学意义（P〈0．05）,但随时间的延长,高度略有下降,椎间隙前缘高度较术前减少,但差异无统计学意义（P〉0．05）。手术节段保持了一定的活动度,但较术前明显减少,差异有统计学意义（P〈0．05）。结论Dynesys动态固定系统结合椎板减压治疗腰椎退变性疾病的早期效果较明显。该手术方案维持了手术节段的椎间隙高度,在稳固脊柱的前提下保留一定活动度,能够预防邻近节段退变及腰椎不稳,但远期的疗效还需进一步深入研究。     

Dynesys动态稳定系统与腰椎退变性疾病

传统的脊柱融合术是治疗腰椎退变性疾病的金标准.越来越多证据表明,融合后腰部活动受限制、脊柱动力学改变和邻近节段加速退变可导致腰椎不稳和椎管狭窄复发.非融合技术也称为动态固定,开始受到关注.非融合固定可通过非融合方法有效改善腰椎节段间的应力传导,缓解疼痛并预防邻近关节退变的发生,其远期效果在于异常活动被控制后,椎间盘在动态固定保护下可自身修复或延缓退变.绝大多数临床结果显示,非融合疗效与传统融合术相当,但创伤较小,不会增加邻近节段继发退变等风险,更符合脊柱生理性稳定.该文主要介绍后路经椎弓根动态稳定系统Dynesys的设计理念、治疗原理、临床应用及治疗效果等.     

动态中和固定系统治疗腰椎退行性疾病的研究进展

动态固定技术治疗腰椎退行性疾病日益成为基础和临床研究的热点。动态中和固定系统(dynamic neutralization system,Dynesys)作为动态固定技术的一种,既能保持脊柱的活动能力,改善患者的临床症状,还在延缓邻近节段退变方面表现出一定的优势。Dynesys技术可作为腰椎融合之外治疗腰椎退行性疾病的另一最佳选择,主要适用于轻至中度的腰椎退变性疾病,但它缺乏保持和恢复腰椎前凸的机制需要患者主动伸展实现前凸。如何延长使用寿命、预防并发症发生等问题有待解决,其远期疗效及延缓邻近节段退变作用机制需进一步明确。     

自动复位内固定器治疗腰椎不稳定

目的 介绍自动复位内固定器及其应用效果。方法 应用自动复位内固定器治疗腰椎不稳定４例,对其临床资料及内固定器结构特点进行分析。结果 ４例随访１．５年,症状和体征完全消失,椎间隙无变窄塌陷,屈伸动力位摄片无椎体滑移。结论 该内固定符合生物力学特性,能增大或维持椎间隙或椎间孔正常高度,有利于植骨融合,操作简单。     

The dynamic neutralization system for the spine: a multi-center study of a novel non-fusion system

European Spine Journal - Various forms of lumbar instability require a surgical stabilization. As an alternative to fusion, a mobile, dynamic stabilization restricting segmental motion would be...     

Soft system Stabilization of the lumbar spine as an alternative surgical modality to lumbar arthrodesis in the facet syndrome

Summary The authors present preliminary results in a series of 27 patients with a lumbar and/or lumbosacral facet syndrome operated on by use of the soft-system-Stabilization (SSS) according to Graf. Attention is paid to the correct selection of patients for this surgical technique. Excellent, good, satisfactory, moderate, and poor results were obtained in 19 (70%), 2 (7.5%), 5 (18.5%), 1 (3.5%), and 0 instances, respectively.The authors think that a Graf-procedure may be indicated in young to middle-aged patients with a lumbar and/or lumbosacral facet syndrome with 1.) no arthrotic changes of the facet joints, 2.) a still intact disc and/or only mild loss of intervertebral distance, 3.) well trained low-back muscles, and 4.) a clear-cut pain relief on test-anaesthesia of articular nerves and trial immobilization in a plastic jacket.     

Biomechanics of the lumbar spine after dynamic stabilization

Target of the study was to predict the biomechanics of the instrumented and adjacent levels due to the insertion of the DIAM spinal stabilization system (Medtronic Ltd). For this purpose, a 3-dimensional finite element model of the intact L3/S1 segment was developed and subjected to different loading conditions (flexion, extension, lateral bending, axial rotation). The model was then instrumented at the L4/L5 level and the same loading conditions were reapplied. Within the assumptions of our model, the simulation results suggested that the implant caused a reduction in range of motion of the instrumented level by 17% in flexion and by 43% in extension, whereas at the adjacent levels, no significant changes were predicted. Numerical results in terms of intradiscal pressure, relative to the intact condition, predicted that the intervertebral disc at the instrumented level was unloaded by 27% in flexion, by 51% in extension, and by 6% in axial rotation, while no variations in pressure were caused by the device in lateral bending. At the adjacent levels, a change of relative intradiscal pressure was predicted in extension, both at the L3/L4 level, which resulted unloaded by 26% and at the L5/S1 level, unloaded by 8%. Furthermore, a reduction in terms of principal compressive stress in the annulus fibrosus of the L4/L5 instrumented level was predicted, as compared with the intact condition. These numerical predictions have to be regarded as a theoretical representation of the behavior of the spine, because any finite element model represents only a simplification of the real structure.     

侧路经皮椎间孔镜技术在腰椎后路术后再次手术中的应用

目的:探讨侧路经皮椎间孔镜技术(transforaminal endoscopic spine system,TESSYS)在腰椎后路术后再次手术中的应用效果。方法:自2012年1月至2013年10月,根据纳入标准,筛选14例腰椎后路术后需要再次手术的患者,应用TESSYS治疗。其中男8例,女6例;年龄27～84岁,平均(50.4±18.9)岁。观察比较手术前后视觉疼痛模拟评分 (visual analogue scale,VAS)及日本骨科协会评分 (Japanese Orthopaedic Association Scores,JOA评分),并采用改良的Macnab标准评估疗效。结果:所有患者获得随访,时间6～27个月,平均18个月。术前及术后1周,3、6个月的VAS分别为6.79±1.31,2.50±1.29,2.21±1.53,1.64±1.08,术后与术前比较差异有统计学意义(P <0.01);JOA评分分别为12.43±1.95,21.50±3.78,21.93±4.55,23.36±4.33,术后较术前明显提高(P <0.01).按改良的Macnab 标准评定,优5例,良7例,可1例,差1例。1例穿刺过程中损伤L5神经根,其余患者无并发症。结论:选择合适的病例,在腰椎后路术后再次手术中应用TESSYS治疗,可以成功避开初次手术瘢痕,减少并发症,取得满意的临床效果。     

K-Rod脊柱动态稳定系统在多节段腰椎退行性疾病中的临床应用

目的:评估K-Rod脊柱动态稳定系统治疗多节段腰椎退行性疾病的临床疗效。方法:2011年10月至2013年10月应用K-Rod脊柱动态稳定系统治疗多节段腰椎退行性疾病20例,男8例,女12例;年龄31～65岁,平均45.4岁;病程9个月～6.25年,平均3.8年。所有患者术前有腰腿痛病史,其中极外侧腰椎间盘突出症10例,腰椎管狭窄症7例,腰椎滑脱3例(Ⅰ度滑脱2例,Ⅱ度滑脱1例),所有病例的责任节段为单节段,并且责任间隙的相邻椎间盘至少有1节已经出现明显退变。进行手术解除神经压迫及植入K-Rod脊柱后路动态稳定系统(其中责任间隙行椎间融合,退变邻椎行动态稳定).采用疼痛视觉模拟评分(VAS)、日本矫形外科协会关于下腰痛的评分标准(JOA)和Oswestry功能障碍指数(ODI)评估临床疗效;通过影像学资料对退变邻椎节段活动度(ROM)、椎间盘高度及椎间盘信号(根据改良Pfirrmann分级系统)进行评估。结果:全部患者获得1年以上随访,术前症状均明显缓解,腰腿痛VAS、JOA及ODI术前与术后1周、术后1年差异均有统计学意义(p<0.05).术后影像学检查见责任节段均已融合,未见内植物松动、移位及断裂。术后相邻椎间盘的ROM有所减少(p<0.05).相邻退变椎间盘的高度术后1年与术前比较差异无统计学意义(p>0.05).对25个相邻椎间盘应用改良Pfirrmann分级系统进行分级并对比,术后1年共有8个(32%)椎间盘在评级中有所好转,15个(60%)椎间盘在评级中无变化,2个(8%)椎间盘在评级中退变加重。结论:应用腰椎融合辅以邻近节段动态固定的K-Rod脊柱动态稳定系统治疗多节段腰椎退行性疾病,可以取得良好的近期临床疗效。     

Short-term effects of a dynamic neutralization system (Dynesys) for multi-segmental lumbar disc herniation

Purpose

To determine the safety and short-term curative effects of internal fixation using a dynamic neutralization system (Dynesys) for multi-segmental lumbar disc herniation (ms-LDH) with the control group treated by posterior lumbar interbody fusion (PLIF).

Methods

Forty-five patients with ms-LDH were selected as study group treated with Dynesys and 40 patients as control group with PLIF. The surgical efficacy was evaluated by comparing the visual analogue scale (VAS) scores, the Oswestry Disability Index (ODI) scores and the ROMs of the adjacent segment before and after surgery. The postoperative complications related to the implants were identified.

Results

All patients were followed up for an average duration of over 30 months. Dynesys stabilization resulted in significantly higher preservation of motion at the index level (p < 0.001), and significantly less (p < 0.05) hypermobility at the adjacent segments. VAS for back and leg pain and ODI improved significantly (p < 0.05) with both the methods, but there was no significant difference between the groups.

Conclusions

The non-fusion fixation system Dynesys is safe and effective regarding short-term curative effects for the treatment of ms-LDH.

     

Stabilization of the lower thoracic and lumbar spine with external skeletal fixation

For stabilization of the lower thoracic and lumbar spine, an external spinal skeletal fixation (ESSF) system has been developed and clinically used since 1977. The system consists of two pairs of Schanz screws and an adjustable external fixation device. The Schanz screws are firmly anchored through the pedicles into the vertebral bodies. Application of ESSF offers some unique characteristics beneficial in the treatment of unstable spinal injuries and spinal osteomyelitis. In contrast to other fixation systems, the number of vertebrae immobilized can be reduced with ESSF. Versatility of the system allows application in every type of spinal instability. Stability obtained with ESSF suffices for early mobilization without major external support in every instance. In laboratory investigation, ESSF proved to be more secure than rod distraction systems and plate fixation. Since 1977, 65 patients were treated with ESSF. All 52 patients who were at least one year postsurgery were personally examined. This group included 42 patients with acute spinal trauma and eight patients with spinal osteomyelitis. Results achieved with ESSF have been encouraging, with no serious complications to date. Future modifications of ESSF application could lead to simplification and facilitation of treatment.     

Factors affecting dynamic foraminal stenosis in the lumbar spine

Background contextLumbar foraminal stenosis is a common clinical problem and a significant cause of lower extremity radiculopathy. Minimal in vivo data exists quantifying changes in foraminal area (FA) as the spine moves from flexion to extension in the lumbar spine or on the relationship between FA and lumbar segmental angular motion, translational motion (TM), or disc bulge migration.PurposeTo use kinetic magnetic resonance imaging (kMRI) to evaluate changes in dimensions of lumbar neural foramina during weight bearing in neutral, flexion, and extension positions. To evaluate the relationship between foraminal stenosis and lumbar segmental angular motion, TM, and disc bulge migration.Study designA retrospective radiographic study.Patient sampleForty-five patients with a mean age of 44 years undergoing kMRI for symptoms of low back pain or radiculopathy.Outcome measuresMagnetic resonance imaging measurements of FA, angular motion, TM, and disc bulge migration.MethodsKinetic magnetic resonance imaging of the lumbar spine was reviewed in 45 patients with low back pain or radiculopathy, and parasagittal images were evaluated for changes in neural foraminal dimensions in various degrees of motion with weight bearing. The changes in foraminal dimension were correlated to the amount of segmental angular motion, TM, and disc bulge migration at each level. Neural foramina were also assessed qualitatively by Wildermuth criteria. Only those foramina that were clearly visualized with well-defined anatomic boundaries in all three positions were taken into consideration. Patients with previous surgery, tumor, and scoliosis were excluded from the study.ResultsThere was a significant decrease in the FA from flexion to neutral (p<.05) at all levels except L5–S1 and from neutral to extension at all levels (p<.05). The average percent decrease in FA was 30.0% with the greatest decrease from flexion to extension occurring at L2–L3 (167–107 mm²) and the smallest change occurring at L5–S1 (135–106 mm²) (p<.05). The magnitude of change in FA increased as angular motion at a segment increased. The mean change in FA was 32.3 mm² when angular motion was less than 5° and was 75.16 mm² when angular motion exceeded 15°. The extent of disc bulging posteriorly in the neural foramen was also correlated with the reduction in the FA from flexion to extension, but TM had no effect.ConclusionsForaminal area decreased significantly in extension compared with flexion and neutral on MRI. Lumbar disc bulge migration and angular motion at each level contributed independently to the decrease in FA in extension, whereas TM had no effect on FA.     

Pedicle screw-based posterior dynamic stabilization in the lumbar spine

Traditionally, management of spinal pathology has centered on decompression, correction of deformity, and stabilization. Deformity correction and stabilization have been accomplished largely by spinal fusion at the pathologic levels. In addition to the risks and potential complications, there are sequelae to a successful fusion. Therefore, attention is being directed toward disk replacement in the lumbar spine. In addition to their preserving motion in the anterior column, several posterior motion-preservation devices have been developed in an effort to prevent pathologic motion at both a decompressed level and a segment adjacent to a fusion. Initial studies suggest that the results of posterior dynamic stabilization may be comparable to those of fusion; however, longer periods of clinical and radiographic follow-up are required to fully define the role these devices may play in the management of the degenerative lumbar spine.     

Muscular contributions to dynamic dorsoventral lumbar spine stiffness

Spinal musculature plays a major role in spine stability, but its importance to spinal stiffness is poorly understood. We studied the effects of graded trunk muscle stimulation on the in vivo dynamic dorsoventral (DV) lumbar spine stiffness of 15 adolescent Merino sheep. Constant voltage supramaximal electrical stimulation was administered to the L3–L4 interspinous space of the multifidus muscles using four stimulation frequencies (2.5, 5, 10, and 20 Hz). Dynamic stiffness was quantified at rest and during muscle stimulation using a computer-controlled testing apparatus that applied variable frequency (0.46–19.7 Hz) oscillatory DV forces (13-N preload to 48-N peak) to the L3 spinous process of the prone-lying sheep. Five mechanical excitation trials were randomly performed, including four muscle stimulation trials and an unstimulated or resting trial. The secant stiffness (k _y = DV force/L3 displacement, kN/m) and loss angle (phase angle, deg) were determined at 44 discrete mechanical excitation frequencies. Results indicated that the dynamic stiffness varied 3.7-fold over the range of mechanical excitation frequencies examined (minimum resting k _y = 3.86 ± 0.38 N/mm at 4.0 Hz; maximum k _y = 14.1 ± 9.95 N/mm at 19.7 Hz). Twenty hertz muscle stimulation resulted in a sustained supramaximal contraction that significantly (P < 0.05) increased k _y up to twofold compared to rest (mechanical excitation at 3.6 Hz). Compared to rest, k _y during the 20 Hz muscle stimulation was significantly increased for 34 of 44 mechanical excitation frequencies (mean increase = 55.1%, P < 0.05), but was most marked between 2.55 and 4.91 Hz (mean increase = 87.5%, P < 0.05). For lower frequency, sub-maximal muscle stimulation, there was a graded change in k _y, which was significantly increased for 32/44 mechanical excitation frequencies (mean increase = 40.4%, 10 Hz stimulus), 23/44 mechanical excitation frequencies (mean increase = 10.5%, 5 Hz stimulus), and 11/44 mechanical excitation frequencies (mean increase = 4.16%, 2.5 Hz stimulus) when compared to rest. These results indicate that the dynamic mechanical behavior of the ovine spine is modulated by muscle stimulation, and suggests that muscle contraction plays an important role in stabilizing the lumbar spine. This study was presented, in part, at the 31st Annual Meeting of the International Society for the Study of the Lumbar Spine, New York, NY, May 11–14, 2005.     

一种新型腰椎动态固定系统的初步生物力学分析

目的设计一种后路腰椎椎弓根动态固定系统,并对其进行生物力学试验,从而为其临床应用提供一定可行性依据。方法选取新鲜小牛腰椎(L2~5),将标本分成4组:A组(正常试验组)、B组(腰椎减压非固定组)、C组(动态系统固定组)、D组(传统坚强钉棒系统固定组),5个标本按一定顺序依次在指定力学测试机器上进行生物力学试验,测定给定载荷下(500、1 000、2 000、3 000、4 000、5 000 N)小牛腰椎标本的形变量,并对相关数据进行统计学分析。结果首先对500 N载荷下的形变量进行统计学分析,500 N载荷下各组样本所在总体的方差齐(Levene值为1.923,P=0.1690.05),ANOVA分析结果显示500 N的负荷下各组形变量不全相同(F=90.251,P0.05),SNK法分析结果显示4组中任意2组之间的差异有统计学意义(P0.05)。测量结果显示在给定压力下B组标本形变量值均大于A组,C、D组标本的形变量值均大于A、B组,C组形变量均大于D组对应值,差异有统计学意义(P0.05)。对4组在1 000 N、2 000 N、3 000 N、4 000 N、5 000 N载荷下也做了同样的比较分析,得到类似的结果。结论新设计的动态固定系统分散了应力的集中,稳定了腰椎,一定程度保留了固定腰椎节段的运动,承载了部分固定邻近节段的负荷,固定有效。