The relationship between disc degeneration and flexibility of the lumbar spine.

BACKGROUND CONTEXT: A relationship between degenerative changes of the intervertebral disc and biomechanical functions of the lumbar spine has been suggested. However, the exact relationship between the grade of disc degeneration and the flexibility of the motion segment is not known. PURPOSE: To investigate the relationship between degenerative grades of the intervertebral disc and three-dimensional (3-D) biomechanical characteristics of the motion segment under multidirectional loading conditions. STUDY DESIGN/SETTING: A biomechanical and imaging study of human cadaveric spinal motion segments. METHODS: One hundred fourteen lumbar motion segments from T12-L1 to L5-S1 taken from 47 fresh cadaver spines (average age at death, 68 years; range, 39 to 87 years) were used in this study. The severity of degeneration (grades I to V according to Thomson's system) was determined using magnetic resonance (MR) images and cryomicrotome sections. Pure unconstrained moments with dead weights were applied to the motion segments in six load steps. The directions of loading included flexion, extension, right and left axial rotation, and right and left lateral bending. RESULTS: When the MR images were graded, 2 segments had grade I disc degeneration; 45, grade II; 20, grade III; 26, grade IV; and 21, grade V. When the cryomicrotome sections were graded, 14 segments had grade I disc degeneration; 31, grade II; 22, grade III; 26, grade IV; and 21, grade V. Segments from the upper lumbar levels (T12-L1 to L3-4) tended to have greater rotational movement in flexion, extension, and axial rotation with disc degeneration up to grade IV, whereas the motion decreased when the disc degenerated to grade V. In the lower lumbar spine at L4-5 and L5-S1, motion in axial rotation and lateral bending was increased in grade III. CONCLUSIONS: These results suggest that kinematic properties of the lumbar spine are related to disc degeneration. Greater motion generally was found with disc degeneration, particularly in grades III and IV, in which radial tears of the annulus fibrosus are found. Disc space collapse and osteophyte formation as found in grade V resulted in stabilization of the motion segments.     

T2* mapping of ovine intervertebral discs: Normative data for cervical and lumbar spine

To obtain T2* values in histologically evaluated healthy ovine intervertebral discs of the cervical and lumbar spine. Intervertebral discs of nine sheep and nine lambs underwent histological assessment with the modified Boos score for grading of disc degeneration. Discs with a score <10 points (maximum = 40 points) underwent T2* mapping (n = 64). Mid‐sagittal T2* values were obtained in five regions: Anterior annulus fibrosus, anterior nucleus pulposus, central nucleus pulposus, posterior nucleus pulposus, and posterior annulus fibrosus. We noted a zonal T2* distribution with high values in the central nucleus and low T2* values in the anterior and posterior annulus fibrosus. The T2* values were higher in lamb than in sheep IVDs for both cervical and lumbar spine (p < 0.001). The T2* values were also higher in the cervical than in the lumbar spine (p = 0.029 for sheep and p < 0.001 for lamb IVDs). The T2* values obtained in these ovine intervertebral discs can serve as baseline values for future T2* measurements both in health and disease. © 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:717–724, 2016.     

The lumbar disc and low back pain.

The lumbar disc serves to sustain compression loads and is subject to tension and shear in forward bending and rotation. Its outer third is innervated and can be a source of pain. The annulus fibrosus may be injured in rotation and flexion of the lumbar spine and may become symptomatic as a ligamentous injury. Compression injuries of the disc are initially asymptomatic but may set in train a degradative process that, in time, leads to internal disc disruption, which becomes symptomatic as a result of chemical or mechanical irritation of nociceptors in the annulus fibrosus. Disc prolapse is but one possible end stage of internal disc disruption and represents the culmination of a series of destructive processes affecting the disc. This condition can be symptomatic while the external appearance of the disc remains normal and before nerve roots are affected in any way.     

Enhanced prolylhydroxylase activity in the posterior annulus fibrosus of canine intervertebral discs following long-term running exercise

Summary The effect of long-term exercise on the intervertebral disc collagen concentration (hydroxyproline), collagen-synthesizing enzymes (prolyl-4-hydroxylase, PH, and galactosyl-hydroxylysyl glucosyltransferase, GGT) and hydroxypyridinium crosslinks was studied in ten female beagle dogs. The dogs were run on a treadmill for 1 year starting at the age of 15 weeks. The daily running distance was gradually increased to 40 km, which distance the dogs ran for the final 15 weeks. Ten untrained dogs from the same breeding colony served as controls. The nucleus pulposus and anterior and posterior halves of the annulus fibrosus of C2–3, T10–12, L4–5 disc segments were analysed. Crosslinks were measured from the anterior annulus fibrosus of the T10–11 disc. Hydroxyproline and hydroxypyridinium concentrations remained similar in both groups. PH and GGT were significantly elevated by running in the posterior annulus fibrosus of the thoracic and lumbar discs and in the lumbar nucleus pulposus. In the thoracic nucleus pulposus GGT was reduced significantly. The results suggest activated collagen metabolism in the posterior annulus fibrosus of the thoracic and lumbar discs as a result of locally increased strains on the spine.The research was carried out at the Department of Anatomy, University of Kuopio     

An observation of ruptured annulus fibrosus in lumbar discs.

To observe anatomical or pathological changes in lumbar intervertebral discs, discography and computed tomography-discography (CTD) were performed on fresh human cadavers. The results of discograms and CTD were compared with histological findings of cross sections of discs. Preoperative CTD of lumbar disc herniation was investigated based on these results. Ruptures of the annulus fibrosus were divided into two categories: circumferential rupture and radial rupture. In CTD images of fresh human cadavers, most images of rupture of the annulus fibrosus showed anterior to lateral circumferential rupture. As disc degeneration progressed, circumferential rupture tended to coexist with radial rupture in many cases. In CTD cases of lumbar disc herniation, most images of ruptures of the annulus fibrosus showed a posterior radial rupture, which was the route for herniated nucleus. The greater the degree of degeneration, the more the images tended to show radial ruptures coexisting with circumferential ruptures.     

Histological changes in intervertebral discs after smoking and cessation: experimental study using a rat passive smoking model

Background Passive smoking has been reported to induce intervertebral disc degeneration in rats, and the objective of the present study was to histologically investigate changes in smoking-induced intervertebral disc degeneration after cessation of smoking. Methods Four-week-old rats were subjected to passive smoking for 8 weeks in a smoking box [20 cigarettes a day: one cigarette an hour (inhaled over 3 minutes and followed by ventilation with room air for 5 minutes)] to induce intervertebral disc degeneration. Smoke-free periods of different lengths were then established, and intervertebral discs were histologically analyzed. Results Immediately after 8 weeks of passive smoking, intervertebral discs exhibited cracks, tears, and misalignment of the annulus fibrosus, and increased fibrous tissue was seen in the nucleus pulposus. In addition, the level of interleukin-1β in intervertebral discs was higher in the smoking group than in the non-smoking group. After cessation, progression of degeneration ceased, and the matrix of the nucleus pulposus and annulus fibrosus exhibited increased fibrous connective tissue and proteoglycan. However, there were no changes in annulus fibrosus misalignment. Interleukin-1β levels also remained significantly elevated after 8 weeks of cessation. Conclusions While the annulus fibrosus degeneration caused by smoking was partially irreversible after cessation of smoking, the amount of mucin (proteoglycan) in the nucleus pulposus and annulus fibrosus tended to increase after cessation, thus suggesting the possibility that smoking-induced intervertebral disc degeneration can be repaired to some degree by cessation of smoking.     

The mechanical response of the lumbar spine to different combinations of disc degenerative changes investigated using randomized poroelastic finite element models

Degeneration of the intervertebral disc is related to progressive changes in the disc tissue composition and morphology, such as water loss, disc height loss, endplate calcification, osteophytosis. These changes may be present separately or, more frequently, in various combinations. This work is aimed to the biomechanical investigation of a wide range of clinical scenarios of disc degeneration, in which the most common degenerative changes are present in various combinations. A poroelastic non-linear finite element model of the healthy L4–L5 human spine segment was employed and randomly scaled to represent ten spine segments from different individuals. Six different degenerative characteristics (water loss in the nucleus pulposus and annulus fibrosus; calcification and thickness reduction of endplate cartilage; disc height loss; osteophyte formation; diffuse sclerosis) were modeled in 30 randomly generated models, 10 for each overall degree of degeneration (mild, moderate, severe). For each model, a daily loading cycle including 8 h of rest, 16 h in the standing position with superimposed two flexion–extension motion cycles was simulated. A tendency to an increase of stiffness with progressing overall degeneration was observed, in compression, flexion and extension. Hence, instability for mild degeneration was not predicted. Facet forces and fluid loss decreased with disc degeneration. Nucleus, annulus and endplate degeneration, disc height loss, osteophytosis and diffuse sclerosis all induced a statistically significant decrease in the total daily disc height variation, facet force and flexibility in flexion–extension. Therefore, grading systems for disc degeneration should include all the degenerative changes considered in this work, since all of them had a significant influence on the spinal biomechanics.     

两种骨水泥渗漏对椎间盘影响的实验研究

目的 探讨椎体成形术时骨水泥渗漏是否会引起椎间盘退变，以及椎间盘退变程度与骨水泥类型是否相关。方法 选用8只成年家犬，以每只犬L2-3、L3-4、L4-5椎间盘为实验对象，随机分为对照组、聚甲基丙烯酸甲酯（polymethylmethacrylate，PMMA）与磷酸钙骨水泥（calcium phosphate cement，CPC）3组。对照组仅行椎间盘穿刺，不注入任何物质，PMMA组及CPC组均各向椎间盘注入0．1ml骨水泥。术前及术后24周摄正、侧位X线片，计算椎间盘高度指数百分数（disc height index percentage，DHIP）。术后24周行MR检查，计算MRI指数。组织学检查参照Masuda标准对椎间盘退变程度评分并分析。结果 术后24周X线片显示对照组椎间隙无狭窄，病理学检查未见椎间盘退变。PMMA、CPC组椎间盘MRI显示：椎间隙有狭窄，R加权像髓核信号不同程度降低且不均一，其相对高信号区面积减小，髓核形态不规则，纤维环与髓核界限不清。组织学检查显示髓核细胞数量不同程度减少，空泡变小。髓核的细胞外基质不同程度压缩，纤维环断裂或扭转。3组DHIP、MRI指数、组织学评分的差异均有统计学意义（P〈0.01）。结论 PMMA、CPC注入椎间盘会导致椎间盘退变，PMMA所致椎间盘退变较CPC更为严重.     

Long‐Term Pathology of Ovine Lumbar Spine Degeneration Following Injury Via Percutaneous Minimally Invasive Partial Nucleotomy

The focus of this work is to assess the long‐term progression of degeneration in the ovine lumbar spine following a minimally invasive model injury comparable to the damage of an intervertebral disc (IVD) herniation. A partial nucleotomy was performed on 18 sheep via the percutaneous dorsolateral approach. The animals were culled at 6 and 12 months to evaluate the damaged and neighboring functional spine units (FSUs) for degenerative characteristics via μ‐CT and histology. Both quantitative μ‐CT and histology investigations demonstrated statistically significant differences between the native and damaged FSUs investigated. Qualitative analysis of μ‐CT revealed numerous pathological markers consistent with intervertebral disc degeneration (IDD), with differences in frequency and severity between the native and damaged FSUs. The annulus fibrosus reforms a pressure seal within 6 weeks, but the extent of the trauma is significant enough to initiate IVD degeneration, which is already clearly visible at 6 months and especially so 12 months post‐op. IDD pathology consistent with signs of a herniation was seen in both the 6‐ and 12‐month groups. This technique provides a useful model injury for the preclinical evaluation of IDD in large animal models, especially in regards to simulating disc herniation as well as for testing the efficacy of associated therapies in the future. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2376–2388, 2019     

Percutaneous Endoscopic Lumbar Discectomy for Lumbar Disc Herniation Using an Endoscopic Staining: A Technical Note

Symptomatic lumbar disc herniation (LDH) is widely treated using percutaneous endoscopic lumbar discectomy (PELD). In the present PELD surgery, performing decompression under endoscope still takes a long time to explore the rupture site of annulus fibrosus, resulting in prolonged operation time and over‐invasion of the undegenerated annulus fibrosus. A wide range of intraoperative exploration also induces an iatrogenic injury of the normal annulus fibrosus, even aggravating intervertebral disc degeneration, which may lead to early postoperative recurrence in severe case. Hence, it is important to seek a precise decompression in PELD surgery. Under this kind of realization, more spinal surgeons possibly choose a disc staining before performing decompression. However, the classical disc staining technique still has its shortcomings. First of all, an appropriate dose of staining cannot be accurately mastered, even induces unqualified staining effect. Second, the duration of surgery and the times of fluoroscopy will be increased. Finally, what surgeons see under the endoscope is the staining result but not the staining process. Hence, this is accomplished more effectively by designing procedures that perform fully visible disc staining under spinal endoscope. There is no specific research to discuss the technique note of endoscopic staining in PELD surgery. We have come up with a new original technology of endoscopic staining with methylene blue injection in PELD for treatment of LDH.     

Influence prediction of injury and vibration on adjacent components of spine using finite element methods

OBJECTIVES: A three-dimensional finite element (FE) model of the lumbar spine L3-L5 segment, the ligaments of which were assumed to be nonlinear materials, was established based on the actual vertebra geometry to investigate the influence of the injury lumbar spine on its adjacent components on the condition of whole-body vibration. Several injury conditions of the spine components were assumed, such as facetectomy, nucleotomy, and removal of bony posterior elements. METHODS: The dynamic FE analyses were carried out for those FE conditions under cyclic compression loads at the frequencies of 5 and 10 Hz. Then a comparison between the dynamic results and the static results was conducted to analyze the influence of both the nucleus injury and the facet joint injury on the adjacent intervertebral discs. RESULTS AND CONCLUSIONS: The results indicate that the lumbar spine exhibits not only vertical vibration but also the flexion--extension motion during vibration. The denucleation will cause high stress and large disc bulge on the disc annulus under vibration. The facet joints of lumbar spine can limit the motion amplitude of flexion-extension and protect both the posterior regions and the posterolateral regions of disc annulus from large strain and stress during vibration. The facet joint removal will increase the stress of disc annulus by around 15% at the posterior region for the conditions of nucleotomy or no vibration. The stress of annulus circumference is higher at the posterolateral region than that of other regions of annulus circumference, and the facet joint removal may exacerbate the intervertebral disc degeneration on the condition of whole-body vibration.     

有限髓核摘除结合纤维环缝合治疗腰椎椎间盘突出症的早期疗效

目的观察有限髓核摘除结合纤维环缝合治疗腰椎椎间盘突出症的早期临床疗效。方法对2015年1月—2016年3月在本院行有限髓核摘除术的59例腰椎椎间盘突出症患者临床资料进行回顾性对照研究。缝合组28例行小切口腰椎椎板开窗有限髓核摘除结合纤维环缝合术;对照组31例行小切口腰椎椎板开窗有限髓核摘除,未行纤维环缝合。采用MacNab标准对术后1、3、6个月的治疗效果进行评价,同时采用椎间盘高度及椎间盘夹角对术后6个月时的脊柱稳定性进行评价。结果术后1、3个月2组Mac Nab评分优良率比较差异无统计学意义;术后6个月时缝合组患者优良率高于对照组,差异有统计学意义(P0.05)。术后6个月时缝合组患者椎间盘高度高于对照组,差异有统计学意义(P0.05),椎间盘夹角小于对照组,差异有统计学意义(P0.05)。随访6个月无复发及再手术患者。结论有限髓核摘除结合纤维环缝合术治疗腰椎椎间盘突出症安全、可靠,能获得满意的早期临床疗效且不影响脊柱稳定性,是降低复发率和再手术风险的一种行之有效的方法,值得临床推广应用。     

三种纤维环处理方式对腰椎生物力学影响的三维有限元分析

目的:通过建立"一"字型切口、环形切口、纤维环缝合的有限元分析模型,利用有限元分析方法,评估三种纤维环处理方式对于腰椎生物力学的影响。方法:选取健康成人L4/5腰椎节段的CT的DICOM结果,通过逆向建模方式建立人体正常腰椎模型、环形切口模型、"一"字型切口模型及缝合模型,测量腰椎在正常轴向压力的情况下,前屈、后伸、侧弯、旋转四种工况下的生物力学数据。结果:通过有限元分析方法计算正常椎体及三种不同纤维环处理方式的模型的应力数据,结果显示纤维环切开后,各种工况下纤维环、髓核的最大应力值均较正常模型增加;纤维环缝合后,在前屈后伸旋转工况下的最大应力,均低于"一"字型切口和环形切口;与未缝合模型相比,纤维环缝合模型的各部分在各种工况下的应力分布都更加均匀。结论:纤维环缝合后椎间盘、髓核和纤维环应力分布较未缝合模型均匀,缓解纤维环切开后造成的纤维环应力集中问题,对维持椎间盘的稳定性及防止术后再突出能起到积极作用。     

Lumbar disc degeneration and segmental instability: a comparison of magnetic resonance images and plain radiographs of patients with low back pain

We analyzed disc space height, angular displacement, tilting movement, and horizontal displacement in 109 patients with low back pain and/or sciatica, on plain radiographs of the lumbar spine. These parameters were compared with the grade of disc degeneration as evaluated by magnetic resonance imaging with the aim of studying lumbar segmental instability. Disc space height decreased in proportion to the grade of disc degeneration. Angular displacement was significantly less with severe disc degeneration, accompanied by a tendency to stabilization of the motion segment. Tilting movement and horizontal displacement. did not correlate with the grade of disc degeneration. Lumbar segmental instability was recognized at all levels even in individuals who appeared to be normal or to have mild disc degeneration. The incidence of lumbar segmental instability at the L3-4 level was significantly higher in patients with normal discs or mild disc degeneration. At the L4-5 and L5-S levels it did not differ between different grades of disc degeneration.     

腰椎间盘退变动物模型的建立

目的　建立腰椎间盘退变的动物模型并行组织学和MRI观察。　方法　健康成年恒河猴 8只 ,手术组 6只 ,在其腰4 ,5、腰5,6、腰6,7椎间盘分别作一 5mm× 3mm切口 ,分别于术前及术后 1、4、8、13、2 0周对手术椎间盘行MRI观察 ;8只恒河猴分别于术前 (对照组 )及术后 4、8、2 0周随机取 2只处死后行椎间盘组织学观察。　结果　正常成年恒河猴腰椎间盘组织学结构特点与人类相似 ;手术椎间盘高信号区域面积的百分比于术后 8、13、2 0周显著减少 (P <0 0 5 ) ;术后 4周椎间盘切口外被纤维组织覆盖 ,术后 8周 ,切口外层纤维样愈合 ,其内无愈合迹象 ,术后 2 0周 ,切口向椎间盘内延伸 ,部分髓核出现纤维化。　结论　恒河猴是一种生理特性与人类相接近的动物 ,以其为对象应用纤维环切开法可以获得可靠的腰椎间盘退变动物模型 ;通过测量MRI轴位T2加权像椎间盘高信号区域面积百分比的方法可于早期无损伤地发现椎间盘退变。     

高强度聚焦超声对离体兔腰椎间盘的生物学效应

目的观察不同剂量高强度聚焦超声对兔离体腰椎间盘的生物学效应。方法取6例剥离软组织的兔腰骶段脊柱标本（L1～S1）。将频率为9.6MHz、脉冲1 000Hz、剂量5W、焦距4mm的高强度聚焦超声从正前方聚焦于6例脊柱的L1S1椎间盘,各持续3、6、9、12、15、18min。此过程中,用热电偶针监测前方纤维环处与髓核交界处、HIFU焦点处、后方纤维环与髓核交界处、椎管内脊髓前表面的温度。结果 HIFU辐照过程中,监测点的温度逐渐升高,但升高的速度逐渐下降。HIFU在椎间盘前、后方纤维环处都能提供50℃以上的高温,并持续6min以上;焦点处能提供80℃以上的高温,并持续6min以上。结论高强度聚焦超声在椎间盘纤维环内可以提供足够高的温度,灭活纤维环内神经感受器可使髓核溶解、变性、萎缩,是治疗椎间盘源性腰痛的潜在方法。     

腰椎间盘MRI高信号区在诊断椎间盘源性下腰痛中的意义

目的:探讨腰椎间盘MRI高信号区(HIZ)在诊断椎间盘源性下腰痛中的作用。方法:对52例经保守治疗无效、CT影像上无腰椎间盘突出的下腰痛患者行腰椎MRI检查和腰椎间盘造影术,分析腰椎间盘MRI高信号区与腰椎间盘造影诱发的下腰痛之间的关系。结果:在行腰椎间盘造影的142个椎间盘中,共有38个椎间盘呈现疼痛复制反应,其中17个椎间盘显示高信号区。这17个有高信号区的椎间盘在椎间盘造影过程中全部呈现2～3级的纤维环破裂和疼痛复制反应。结论:无椎间盘突出的下腰痛患者在腰椎MRI上存在椎间盘内高信号区,可表明该椎间盘是产生腰痛的破裂椎间盘。     

An in vivo model of degenerative disc disease.

Although the precise etiology of low back pain is disputed, degeneration of the intervertebral disc is believed to play an important role. Many animal models have been described which reproduce the changes found in degenerative disc disease, but none allow for efficient, large-scale testing of purported therapeutic agents. The purpose of this study was to develop a simple animal model resembling degenerative disc disease using the intervertebral discs found in the tails of rats. The proximal two intervertebral discs in the tails of 20 rats were injected with either chondroitinase ABC or control (phosphate buffered saline, PBS). The tails were harvested at 2 weeks, and measurements were made of intervertebral disc height (measured radiographically and histologically), biomechanics (stiffness, hysteresis, and residual deformation), and histologic appearance. Treatment with chondroitinase ABC resulted in a significant loss in intervertebral disc height (radiographic intervertebral disc height, p=0.001; histologic intervertebral disc height, p<0.001) and significant increases in all biomechanical parameters (stiffness, p<0.001; hysteresis, p=0.006; residual deformation, p=0.004) compared to PBS controls. Intervertebral discs treated with chondroitinase ABC had significantly lower histologic grades for each grading category (nucleus pulposus (NP), annulus fibrosus, and proteoglycan staining) compared to controls. The results of injury with chondroitinase ABC were similar to the findings in degenerative disc disease: reduced intervertebral disc height, diminished proteoglycan content, loss of NP cells, and increased stiffness of the disc. Thus, the model appears to be a reasonable tool for the preliminary in vivo evaluation of proposed treatments for degenerative disc disease.     

Motion in lumbar functional spine units during side bending and axial rotation moments depending on the degree of degeneration

STUDY DESIGN: Human lumbar spine specimens were tested in axial rotation and side bending. Motion was related to the grade of degeneration. OBJECTIVES: To determine the degree to which degeneration with fissure formation in the disc affects axial rotation of the lumbar functional spine unit. SUMMARY OF BACKGROUND DATA: There is controversy in the literature regarding the influence of severe degeneration and fissures of the disc on the range of axial rotation. METHODS: Thirty-six lumbar spine specimens were tested in axial rotation and side bending, by applying pure moments in an unconstrained setting. The motion in 6 df was recorded by dial gauges. The grade of degeneration was established by the grading schemes of Nachemson, Thompson, Adams, and Mimura. RESULTS: A significant increase of axial rotation and lateral translation under torque was found. This increase mainly took place between Grade 3 according to the schemes of Nachemson, Thompson, and Adams (no fissure formation) and the higher grades of degeneration (defined by fissure formation). Reduced disc height was always associated with fissures. CONCLUSIONS: A reduced lumbar disc height in radiographs seems to be associated with fissure formation in the disc. In this case, the range axial rotation after torque is increased in comparison with cases with less degeneration.     

Magnetic resonance imaging in the diagnosis of protrusion of a lumbar vertebral disc

Signals of MR images which were done preoperatively on 86 patients with protrusion of lumbar vertebral disc were correlated to operative findings that were grouped, according to condition and position of the nucleus pulposus with relation to its annulus fibrosus, into 3 categories: protrusion, herniation and extrusion. Each of these 3 pathologic conditions was well-reflected on MRI image, a recognizable unique signal, characteristic of each category. Accordingly, the preoperative diagnosis in this series was 96.5% accurate, much better than that with any other methods; better still, MR imaging is non-invasive.