Biomechanical evaluation of segmental instability in degenerative lumbar spondylolisthesis

Here we investigated the biomechanical properties of spinal segments in patients with degenerative lumbar spondylolisthesis (DLS) using a novel intraoperative measurement system. The measurement system comprised spinous process holders, a motion generator, a load cell, an optical displacement transducer, and a computer. Cyclic displacement of the holders produced flexion-extension of the segment with all ligamentous structures intact. Stiffness, absorption energy (AE), and neutral zone (NZ) were determined from the load-deformation data. Forty-one patients with DLS (M/F = 15/26, mean age 68.6 years; Group D) were studied. Adjacent segments with normal discs in six patients (M/F = 3/3, mean age 35 years) were included as a control group (Group N). Flexion stiffness was significantly lower in Group D than in Group N. The NZ, however, was significantly greater in Group D than in Group N. Thus, compared to normal segments, spinal segments with DLS had a lower flexion stiffness and a higher NZ. NZs in Group D were, however, widely distributed compared to those in Group N that showed NZ <2 mm/N in all cases, suggesting that the segment with DLS is not always unstable and that the segments with NZ >2 mm/N can be considered as unstable. A patent application for the intraoperative measurement system has been submitted.     

Kinetic magnetic resonance imaging analysis of lumbar segmental mobility in patients without significant spondylosis

Purpose

The purpose of this study was to examine lumbar segmental mobility using kinetic magnetic resonance imaging (MRI) in patients with minimal lumbar spondylosis.

Methods

Mid-sagittal images of patients who underwent weight-bearing, multi-position kinetic MRI for symptomatic low back pain or radiculopathy were reviewed. Only patients with a Pfirrmann grade of I or II, indicating minimal disc disease, in all lumbar discs from L1–2 to L5–S1 were included for further analysis. Translational and angular motion was measured at each motion segment.

Results

The mean translational motion of the lumbar spine at each level was 1.38 mm at L1–L2, 1.41 mm at L2–L3, 1.14 mm at L3–L4, 1.10 mm at L4–L5 and 1.01 mm at L5–S1. Translational motion at L1–L2 and L2–L3 was significantly greater than L3–4, L4–L5 and L5–S1 levels (P < 0.007). The mean angular motion at each level was 7.34° at L1–L2, 8.56° at L2–L3, 8.34° at L3–L4, 8.87° at L4–L5, and 5.87° at L5–S1. The L5–S1 segment had significantly less angular motion when compared to all other levels (P < 0.006). The mean percentage contribution of each level to the total angular mobility of the lumbar spine was highest at L2–L3 (22.45 %) and least at L5/S1 (14.71 %) (P < 0.001).

Conclusion

In the current study, we evaluated lumbar segmental mobility in patients without significant degenerative disc disease and found that translational motion was greatest in the proximal lumbar levels whereas angular motion was similar in the mid-lumbar levels but decreased at L1–L2 and L5–S1.     

Measurement of angular and linear segmental lumbar spine flexion-extension motion by means of image registration

Background The presently available method of measuring segmental lumbar spine mobility by means of superimposition of lumbar spine radiographs in flexion and extension lacks precision due to differences in the cortical outline of the vertebral bodies in flexed and extended position. The introduction of digital image processing has opened the possibility of computerised superimposition (matching) of digital vertebral body images by means of image registration. Theoretically this technique allows more accurate image matching and, consequently, greater precision of measurement because the whole vertebral body image (not only its cortical outline) can be chosen as region of interest, with registration of all available digital information within this region.Methods To check accuracy and convenience of the new method, two computer program experts performed five image registration measurements of the five lumbar motion segments in five consecutive flexion-extension studies of old lumbar fracture, spondylolytic spondylolisthesis and degenerative anterolisthesis. For comparison an experienced radiologist performed the same repeated measurements with the manual superimposition method.Results Measurement error of the image registration method proved to be significantly smaller than that of the manual superimposition method. There was no overlap between the 95% confidence intervals of the mean standard deviations of experts A and B using the image registration method and the 95% confidence interval of the mean standard deviations of the experienced radiologist using the manual superimposition method. Besides, the image registration method proved to be more convenient because the whole procedure from import of the image data to display of the measurement outcomes lasted 2–3 min compared to 3–6 min for the superimposition method.     

Failed back surgery syndrome: the role of symptomatic segmental single-level instability after lumbar microdiscectomy

Segmental instability represents one of several different factors that may cause or contribute to the failed back surgery syndrome after lumbar microdiscectomy. As segmental lumbar instability poses diagnostic problems by lack of clear radiological and clinical criteria, only little is known about the occurrence of this phenomenon following primary microdiscectomy. Retrospectively, the records of 2,353 patients were reviewed according to postoperative symptomatic segmental single-level instability after lumbar microdiscectomy between 1989 and 1997. Progressive neurological deficits increased (mean of 24 months; SD: 12, range 1–70) after the initial surgical procedure in 12 patients. The mean age of the four men and eight women was 43 years (SD: 6, range 40–77). The main symptoms and signs of secondary neurological deterioration were radicular pain in 9 of 12 patients, increased motor weakness in 6 of 12 patients and sensory deficits in 4 of 12 patients. All 12 symptomatic patients had radiological evidence of segmental changes correlating with the clinical symptoms and signs. All but one patient showed a decrease in the disc height greater than 30% at the time of posterior spondylodesis compared with the preoperative images before lumbar microdiscectomy. All patients underwent secondary laminectomy and posterior lumbar sponylodesis. Postoperatively, pain improved in 8 of 9 patients, motor weakness in 3 of 6 patients, and sensory deficits in 2 of 4 patients. During the follow-up period of 72±7 months, one patient required a third operation to alleviate spinal stenosis at the upper end of the laminectomy. Patients with secondary segmental instability following microdiscectomy were mainly in their 40s. Postoperative narrowing of the intervertebral space following lumbar microdiscectomy is correlated to the degree of intervertebral disc resection. It can therefore be concluded that (1) patients in their 40s are prone to postoperative narrowing of the intervertebral disc space and hence subsequent intervertebral instability and (2) that a small extent of intervertebral disc resection and preservation of the segmental frame may be beneficial in those patients. The present study demonstrated for the first time that the degree of extensive operative techniques in microdiscectomy increased the risk of subsequent segmental instability. In addition, narrowing of the intervertebral space of more than 30% represents a clear radiological sign of segmental instability.Presented in part at the International Congress on Pain Management and Failed Back Surgery Syndrome, Rotterdam, The Netherlands, November 9–12, 1998     

后路椎体间融合术治疗腰椎节段性不稳定

目的：探讨后路椎体间融合术(PLIF手术)治疗腰椎节段性不稳定的临床疗效，比较不同种类的椎间融合技术。方法：本组采用3种PLIF手术治疗腰椎节段性不稳定患者72例，共82个节段。其中椎体滑脱28例，间盘突出合并节段性不稳定19例，不稳定型椎管狭窄25例。3种椎间融合技术包括：单纯植骨、双侧椎问支撑器、单侧斜行椎间支撑器，术中均采用椎弓根固定系统辅助，后2种方法中在安放内置物的同时，均辅以椎间自体骨屑植骨。结果：术后随访6个月～5年8个月，平均3年6个月。4～6个月后均达骨性愈合，无固定螺钉松动、断裂及再滑脱现象。患者的腰痛、下肢疼痛症状均有明显缓解，绝大多数病人恢复原正常的工作和生活。VAS疼痛分值术前平均为7.4分，术后下降至3.1分。功能评定结果：优41例，良24例，可7例，差0例，优良率为90．28％。结论：PLIF手术是治疗腰椎不稳症的一种可靠手段，只要把握手术适应证，可以取得满意的结果。     

中老年腰腿痛患者腰椎终板Modic改变的分布情况及其与腰椎不稳的关系

目的:探讨中老年腰腿痛患者腰椎终板Modic改变的分布情况,分析其与腰椎不稳之间的关系。方法:随机选取2007年3月~2011年12月因腰腿痛在我院行腰椎MRI和常规X线片检查的年龄≥40岁的患者430例,男210例,女220例,年龄40~73岁。观察患者腰椎终板Modic改变的发生率、类型及分布特点;根据腰椎是否稳定分为腰椎稳定组和腰椎不稳定组,分析其与Modic改变之间的关系;腰椎稳定组患者分为腰椎曲度正常组和异常组,分析其与Modic改变之间的关系。结果:430例共计2150个腰椎椎间盘中,124例(28.84%)154个(7.16%)椎间盘终板存在Modic改变,其中Ⅰ型34例(7.91%)、34个椎间盘(1.58%),Ⅱ型72例(16.74%)、100个椎间盘(4.65%),Ⅲ型18例(4.19%)、20个椎间盘(0.93%);L2/3 14个,L3/4 24个,L4/5 50个,L5/S1 66个,其发生率分别为0.65%、1.12%、2.32%、3.07%;其中Modic改变位于终板前部79个,后部31个,整个终板44个;仅累及上终板52个,仅累及下终板41个,累及上、下终板61个。腰椎不稳定组终板Modic改变的发生率为36.68%,腰椎稳定组为19.90%,两组差异有统计学意义(P<0.05);ModicⅠ、Ⅱ、Ⅲ型中腰椎不稳的发生率分别为82.35%、69.44%、33.33%,三者差异有统计学意义(P<0.05);腰椎曲度正常组终板Modic改变的发生率为11.11%,腰椎曲度异常组为23.91%,两组差异有统计学意义(P<0.05)。结论:中老年腰腿痛患者腰椎终板Modic改变以Ⅱ型最多见,以L4/5和L5/S1节段多发;其与腰椎不稳和腰椎曲度之间存在相关关系,ModicⅠ型改变与腰椎不稳相关性最强。     

PLIF治疗腰椎节段性不稳定

目的探讨应用PLIF治疗腰椎节段性不稳定的适应性。方法 2002-12-2010-10我院采用PLIF技术治疗腰椎节段性不稳定患者30例,男19例,女11例,年龄24～69岁,平均45.8岁。失稳节段:L3-46例,L4-511例,L5-S113例。3种椎间融合术包括:单纯椎体间植骨、双侧椎体间融合器、单侧斜行椎间融合器,术中均采用椎弓根固定系统辅助,后2种方法中在安放内置物的同时,均辅以椎间自体骨粒植骨。临床恢复情况按Nakai分级;疗效评定按照目测视觉类比评分法(visualanalogue scale VAS)。结果随访3个月～6年9个月,平均3年7个月。术后18个月时按Nakai标准评定:优19例,良9例,可2例;优良率93.3%。患者的腰痛、下肢疼痛症状均有明显缓解,绝大多数患者恢复正常的工作和生活。结论 PLIF手术是治疗腰椎节段性不稳定比较可靠的方法,只要把握手术适应证,可以取得满意的结果。     

腰椎节段性失稳的概念及诊断进展

在整个脊柱运动范围中存在着一个中性区域,在这个区域内,脊柱活动时受到的阻力较小。腰椎节段性失稳的定义是在生理载荷下,脊柱的稳定系统将脊柱运动的中性区域维持在生理范围内的能力减退,从而出现脊柱的畸形、神经症状和不能忍受的疼痛。脊柱的稳定系统由被动系统、主动系统和神经控制系统组成。腰椎节段性失稳是腰椎退变过程中一个暂时的阶段。腰椎屈伸侧位片拍摄的是腰椎活动的最后阶段,只反应了脊柱被动系统的功能,而没有反应主动系统和神经控制系统的功能。因为临床表现、腰椎正侧位片和体格检查可以反应脊柱的中性区城和稳定系统,所以能作为诊断腰椎节段性失稳的依据。     

Spondylodesis in the treatment of segmental instability of the lumbar spine with special reference to clinically verified instability

Summary We analysed the outcome of 42 consecutive patients suffering from low back pain and segmental instability of the lumbar spine who underwent spondylodesis with transpedicular fixation. There were 29 (69%) females and 13 (31%) males with a mean age of 47±9 years (range 23 to 66 years). The presence of clinically verified instability was a basic requirement for operative treatment, with at least one clinical sign of instability positive in all patients. Radiological signs of instability were detected in only 74 % of the patients.After a postoperative follow-up of one year, lumbar fusion was found in 38 (90%) patients. The fusion was classified as complete in 18 (43%) and as partial in 20 (47%) patients. No fusion there was detected in 4 (10%) patients. Low back pain was completely abolished in 19 (45%) and markedly diminished in 15 (36 %) patients. In 7 (17%) patients, low back pain had remained unchanged and become worse in 1 (2%) patient. Clinical signs and symptoms of instability were still detected in 10 (24%) patients. As compared to the pre-operative situation, the decrease in clinical instability was statistically significant (p = 0.02). Moreover, a significant correlation was observed between the persistence of clinically verified instability and a poor postoperative outcome in daily activities. Of all patients, 17 (40%) returned to work during the period of followup. Based on the good outcome of our patients, the results of this study show that clinical signs and symptoms of instability can be successfully used as selection criteria for lumbar spondylodesis.     

腰椎峡部裂滑脱动态摄片及其临床意义

目的 :探讨腰椎峡部裂滑脱动态摄片的临床意义。方法 :对 5 2例有症状的腰椎弓峡部裂滑脱患者分为两组(轻 中度组和重度组 )进行过屈 /过伸、牵引 /负重动态摄片 ,观察水平位移范围与矢状面旋转角度 ,并与正常组 (10例成年男性自愿者 )和无症状组 (8例无症状腰椎峡部裂者 )比较。结果 :正常组与无症状组间无显著性差异 ;轻 中度症状组与重度症状组间有显著性差异 ;无症状组与有症状组间亦有显著性差异。结论 :腰椎峡部裂滑脱患者临床症状的严重程度与动态滑移密切相关 ;常规前屈 /后伸及过伸 /过屈位X线检查未能显示的节段不稳定 ,通过牵引 /负重动态摄片可显示。     

运动捕捉坐位腰椎旋转手法运动力学参数及相关影响因素

目的：探讨患者个体特征对坐位腰椎旋转手法操作运动力学参数的影响。方法：2016年1月至2016年12月就诊的退行性腰椎滑脱患者30例,男18例,女12例;年龄45～61（52.33±2.34）岁;病程2～72（29.13±3.23）个月。应用运动捕捉技术,测量同一手法操作者向30例患者施者行坐位腰椎旋转手法的运动力学参数,包括旋扳时间、最大速度、最大加速度。对比术者左右手参数不同,分析不同个体特征对坐位腰椎旋转手法操作运动力学参数影响。结果：坐位腰椎旋转手法运动力学参数包括旋扳时间、最大速度、最大加速度,左右手施行的坐位腰椎旋转手法的力学参数差异无统计学意义（P>0.05）。经多元线性回归分析,患者的年龄对操作者的旋扳时间相关具有显著性（P<0.01）;患者的身高对操作者的最大速度与最大加速度有显著的相关性（P<0.01）。结论：左右手施行的坐位腰椎旋转手法有相近的力学参数,因此左右手的手法操作在临床应用上并无较大区别。经过研究发现,在坐位腰椎旋转手法操作过程中,受试者的年龄、身高等均是重要的影响因素。     

应用TSRH椎弓根钉系统治疗腰椎不稳症

目的：评价ＴＳＲＨ椎弓根钉系统在治疗腰椎不稳症中效果。方法：对２１例腰椎不稳症患者行ＴＳＲＨ椎根钉系统内固定手术,术后随诊分析。结果：２１例获平均２０．９个月的随访,植骨晤率为９５．２％,疗效满意。结论：ＴＳＲＨ椎弓根钉系统简单、固定牢靠,适用于腰椎不稳症的手术治疗。     

Kinematics of the lumbar spine in trunk rotation: in vivo three-dimensional analysis using magnetic resonance imaging

In vivo three-dimensional (3D) kinematics of the lumbar spine has not been well evaluated by the conventional methods because of their methodological limitations, while 3D intervertebral motions have been quantitatively determined by cadaver studies. We thus developed a novel 3D analyzing system for the relative motions of individual vertebrae using 3D magnetic resonance imaging (MRI) and analyzed in vivo 3D intervertebral motions of the lumbar spine during trunk rotation. Ten healthy volunteers underwent 3D MRI of the lumbar spine in nine positions with 15° increments during trunk rotation (0°, 15°, 30°, 45°, and maximum). Relative motions of the lumbar spine were calculated by automatically superimposing a segmented 3D MRI of the vertebra in the neutral position over images of each position using the voxel-based registration method. These 3D motions were represented with 6 degrees of freedom by Euler angles and translations on the coordinate system. The mean axial rotation of ten healthy volunteers of each lumbar spinal segment in 45° trunk rotation to each side ranged from 1.2° to 1.7°. Coupled flexion with axial rotation was observed at the segments from L1/2 to L5/S1. Coupled lateral bending of the segments from L1/2 to L4/5 was in the opposite direction of the trunk rotation, while that of T12/L1 and L5/S1 was in the same direction. The direction of the coupled lateral bending in the present study was different from that in the previous cadaver study only at L4/5. This difference might result from the non-load state of the supine position in the current study and/or the non-physiological state in the cadaver study. Our system has two limitations: (1) the study was conducted with each volunteer in the supine position, and (2) because the rotation device regulated trunk rotation, trunk rotation might not have been physiological. In vivo 3D intervertebral motions of the lumbar spine during trunk rotation were evaluated using our novel motion analysis system. These data may be useful for the optimal orthopaedic management of lumbar spinal disorders. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Kinematic and temporal interactions of the lumbar spine and hip during trunk extension in healthy male subjects

Kinematic properties of trunk extension are considered sensitive differentiators of movement between asymptomatic and low back pain subjects. The aim of this study was to quantify the continuous interaction of the hip and lumbar spine kinematics and temporal characteristics as a function of direction during the task of trunk bending backwards and returning to the upright position in healthy young subjects. The sagittal hip and lumbar spine kinematics during the extension task were examined in 18 healthy male subjects. Five trials of trunk extension were recorded for each subject and paired t-tests were then used to determine significant differences (P < 0.05) between the mean lumbar and the hip time-normalized kinematic and temporal variables. The data from the full cycle of trunk extension was analyzed with respect to movement initiation, time to reach peak velocity and peak angular displacement during the full cycle of trunk extension. Three distinct phases of movements were identified based on the continuous movement trajectories of velocity and angular displacement in the lumbar spine and hip; that of extension, return and, a terminal overcorrection phase. There were significant differences identified in the respective mean peak angular velocities of the lumbar spine (21.7 +/- 8.6, 37.0 +/- 14.7, 8.3 +/- 5.0 deg/s) when compared with those of hip (14.6 +/- 6.1, 21.7 +/- 8.5, 5.4 +/- 3.5 deg/s) in each of these three phases. The lumbar spine initiated the movement of trunk extension when bending backwards and returning to the upright position significantly early than that of the hip. These results highlight that in normal healthy adults there is the tendency for the lumbar spine to dominate over the hip during the task of backward trunk bending in terms of the amount and velocity of movement. At the end of extension the kinematics of the lumbar spine and hip kinematic are characterized by a terminal overcorrection phase marking the completion of the movement.     

Effect of a novel interspinous implant on lumbar spinal range of motion

Interspinous devices have been introduced to provide a minimally invasive surgical alternative for patients with lumbar spinal stenosis or foraminal stenosis. Little is known however, of the effect of interspinous devices on intersegmental range of motion (ROM). The aim of this in vivo study was to investigate the effect of a novel minimally invasive interspinous implant, InSwing^®, on sagittal plane ROM of the lumbar spine using an ovine model. Ten adolescent Merino lambs underwent a destabilization procedure at the L1–L2 level simulating a stenotic degenerative spondylolisthesis (as described in our earlier work; Spine 15:571–576, 1990). All animals were placed in a side-lying posture and lateral radiographs were taken in full flexion and extension of the trunk in a standardized manner. Radiographs were repeated following the insertion of an 8-mm InSwing^® interspinous device at L1–L2, and again with the implant secured by means of a tension band tightened to 1 N/m around the L1 and L2 spinous processes. ROM was assessed in each of the three conditions and compared using Cobb’s method. A paired t-test compared ROM for each of the experimental conditions (P < 0.05). After instrumentation with the InSwing^® interspinous implant, the mean total sagittal ROM (from full extension to full flexion) was reduced by 16% from 6.3° to 5.3 ± 2.7°. The addition of the tension band resulted in a 43% reduction in total sagittal ROM to 3.6 ± 1.9° which approached significance. When looking at flexion only, the addition of the interspinous implant without the tension band did not significantly reduce lumbar flexion, however, a statistically significant 15% reduction in lumbar flexion was observed with the addition of the tension band (P = 0.01). To our knowledge, this is the first in vivo study radiographically showing the advantage of using an interspinous device to stabilize the spine in flexion. These results are important findings particularly for patients with clinical symptoms related to instable degenerative spondylolisthesis.     

Reliability of computer-assisted lumbar intervertebral measurements using a novel vertebral motion analysis system

Background contextTraditional methods for the evaluation of in vivo spine kinematics introduce significant measurement variability. Digital videofluoroscopic techniques coupled with computer-assisted measurements have been shown to reduce such error, as well as provide detailed information about spinal motion otherwise unobtainable by standard roentgenograms. Studies have evaluated the precision of computer-assisted fluoroscopic measurements; however, a formal clinical evaluation and comparison with manual methods is unavailable. Further, it is essential to establish reliability of novel measurements systems compared with standard techniques.PurposeTo determine the repeatability and reproducibility of sagittal lumbar intervertebral measurements using a new system for the evaluation of lumbar spine motion.Study designReliability evaluation of digitized manual versus computer-assisted measurements of the lumbar spine using motion sequences from a videofluoroscopic technique.Patient sampleA total of 205 intervertebral levels from 61 patients were retrospectively evaluated in this study.Outcome measuresCoefficient of repeatability (CR), limits of agreement (LOA), intraclass correlation coefficient (ICC; type 3,1), and standard error of measurement.MethodsIntervertebral rotations and translations (IVR and IVT) were each measured twice by three physicians using the KineGraph vertebral motion analysis (VMA) system and twice by three different physicians using a digitized manual technique. Each observer evaluated all images independently. Intra- and interobserver statistics were compiled based on the methods of Bland-Altman (CR, LOA) and Shrout-Fleiss (ICC, standard error of measurement).ResultsThe VMA measurements demonstrated substantially more precision compared with the manual technique. Intraobserver measurements were the most reliable, with a CR of 1.53 (manual, 8.28) for IVR, and 2.20 (manual, 11.75) for IVT. The least reliable measurements were interobserver IVR and IVT, with a CR of 2.15 (manual, 9.88) and 3.90 (manual, 12.43), respectively. The ICCs and standard error results followed the same pattern.ConclusionsThe VMA system markedly reduced variability of lumbar intervertebral measurements compared with a digitized manual analysis. Further, computer-assisted fluoroscopic imaging techniques demonstrate precision within the range of computer-assisted X-ray analysis techniques.     

腰椎间盘突出症合并节段性不稳的治疗

目的　探讨腰椎间盘突出症合并节段性不稳的诊断与治疗方法。方法　行两侧扩大开窗摘除椎间盘 ,并作椎体间植骨融合。结果　植骨块 2～ 4个月愈合 ,手术优良率 87 5 %。结论　治疗腰椎间盘突出症合并节段性不稳时 ,应把恢复该节段的稳定作为重点 ,摘除椎间盘后行椎体间植骨融合。     

The influence of cancellous bone density on load sharing in human lumbar spine: a comparison between an intact and a surgically altered motion segment

The aim of the current study is twofold: first, to compare load sharing in compression between an intact and a surgically repaired lumbar spine motion segment L3/4 using a biomechanically validated finite element approach; second, to analyse the influence of bone mineral density on load sharing. Six cadaveric human lumbar spine segments (three segments L2/3 and three segments L4/5) were taken from fresh human cadavers. The intact segments were tested under axial compression of 600 N, first without preload and then following instrumented stabilisation. These results were compared to a finite element model simulating the effect of identical force on the intact segments and the segments with constructs. The predictions of both the intact and the surgically altered finite element model were always within one standard deviation of the mean stiffness as analysed by the biomechanical study. Thus, the finite element model was used to analyse load sharing under compression in an intact and a surgically repaired human lumbar spine segment model, using a variety of E moduli for cancellous bone of the vertebral bodies. In both the intact and the surgically altered model, 89% of the applied load passed through the vertebral bodies and the disc if an E modulus of 25 MPa was used for cancellous bone density. Using 10 MPa--representing soft, osteoporotic bone--this percentage decreased, but it increased using 100 MPa in both the intact and the altered segment. Thus, it is concluded that reconstruction of both the disc and the posterior elements with the implants used in the study recreates the ability of the spine to act as a load-sharing construction in compression. The similarity in load sharing between normal and instrumented spines appears to depend on assumed bone density, and it may also depend on applied load and loading history.     

Spondylolisthesis with postural slip reduction shows different motion patterns with video-fluoroscopic analysis

To compare the motion of lumbar spondylolisthesis between the standing and decubitus positions and to identify the radiological parameters concerning segmental instability, the lumbar sagittal motion of 5 volunteers and 14 patients was recorded using video-fluoroscopy in both positions. Still images at three frames per second were captured, and the motion pattern was compared between the two positions. Patients were classified into two subgroups according to the degree of postural slip reduction. In the volunteer group, the motion patterns were not particularly different between the two positions. In the small postural reduction group, the motion patterns were not particularly different between the two positions, except in one patient for whom the range of motion (ROM) at the upper adjacent level increased in the decubitus position. In the large postural reduction group, a motion pattern change was observed. The ROM at the slip level in three patients increased, and in the remaining four patients the angle at the midpoint in ROM at the slip level shifted to the extension side in the decubitus position. This condition (anterior slip being reduced in the supine position, with disc angle and average disc height increased) is thought to result from anterior column deficiency and the vertical laxity of the surrounding soft tissues. A biomechanically stable fusion technique is recommended for surgical management.     

Determination of trunk motion patterns associated with permanent or transient stenosis of the lumbar spine

Dynamometric devices used to assess back function are becoming increasingly used in research as well as in clinical practice. These devices provide values for a variety of movement variables such as torque, displacement, and velocity, but they also enable the study of movement patterns. The purpose of this study was to determine the movement patterns of patients presenting with specific spinal pathologies. Thirteen patients with spinal stenosis and 14 patients with degenerative changes and a borderline spinal canal diameter, as well as a control group of 30 symptom-free subjects, were studied. An isoinertial trunk-testing dynamometric device was used. Sagittal velocity and position were measured against a resistance set to 50% of the subject's maximum isometric torque. A phase plane analysis (velocity against position) was performed for each subject. An ensemble averaging technique was used to average the repetitions of every subject and a normalization technique was employed to draw an average graph for each group. This graph showed distinct patterns of movement for the three groups. The differences appeared mostly during the extension phase of movement, as confirmed by statistical analysis. The spinal stenosis group showed lower velocities than the controls during the entire extension phase (P<0.05), while the borderline spinal canal group demonstrated a significant decrease in velocity at the end of the extension phase (P<0.01). These findings can be related to the increase in disk bulge and decrease in the diameter of the spinal canal during extension. This study shows the relation between some spinal pathologies and movement patterns. This type of functional assessment may be a valuable tool for assessing the relation between anatomical lesions and function and for determining the responsibility of findings such as bulging disk and/or facet syndrome in causing a patient's complaints.