Aging in the lumber spine. III. L5

The fifth lumbar vertebra, like the other units of the lumbar spine, shows a significant trend toward lowering and broadening of the body with age. In most individuals the pedicales of L5 arise from the lateral surface of the body, rather than posteriorly as in the other lumbar vertebrae, and the increase in body breadth is very often associated with the formation of reinforcing columns of bone between the bases of the pedicles and osteophytes bordering the inferior endplate. In L5 midbody breadth shows a greater gain than endplate breadths, so "flaring" is decreased with age, a change that is statistically significant in Black males and White females. This vertebra shows no significant change in endplate biconcavity or posterior wedging with age.     

Aging in the lumbar spine. II. L1 and L2

The bodies of the first and second lumbar vertebrae, like those of L3 and L4, show a significant trend toward lowering and broadening with age. Superior, inferior, and midbody transverse breadths increase, but there is little or no increase in endplate "flaring" with age. There is essentially no change in the relationship between anterior and posterior heights, but as reported for L3 and L4, there is a sexual difference in the amount and type of wedging of the bodies of L1 and L2. Posterior wedging (posterior height less than anterior height) of these vertebrae is about twice as common in females as in males. Whites of both sexes show a statistically significant relationship between age and increased biconcavity of the endplates. Black females, but not the males, show a similar trend, especially in L1.     

腰椎后路手术肠道菌群变化的研究

目的探讨腰椎后路手术患者肠道菌群的变化以期更合理的指导临床治疗。方法选择58例腰椎后路手术患者,出现肠道菌群失调症者38例,未出现肠道菌群失调症的20例作为对照组。在腰椎后路手术后,分别取2组患者自然排出的新鲜粪便10 g,采用定性定量检测比较2组患者肠道主要菌群差异及B/E值。肠道菌群失调症患者且与手术前自然排出的新鲜粪便进行相同比较。结果试验组肠道的双歧杆菌、类杆菌数量及B/E值较对照组均减少,分别是:9.21±0.65 vs 10.12±0.85;10.02±0.45 vs 10.23±0.45;1.05±0.17 vs 6.99±1.24,差异有统计学意义(P<0.05);而肠杆菌、肠球菌数量较对照组增加,分别是:9.11±1.09 vs 8.55±0.89;7.80±1.02vs 7.29±0.98,差异有统计学意义(P<0.05)。小梭菌、乳杆菌与对照组相比较,差异无统计学意义(P>0.05)。肠道菌群失调症患者与手术前进行比较,差异无统计学意义(P>0.05)。结论腰椎后路手术出现肠道菌群失调患者专性厌氧菌减少,条件致病菌增加,肠道微生物定植抗力下降。正确及时地去除病因,尽可能地采取微创手术技术,减少医源性损伤,调整机体免疫功能,纠正营养不良,合理使用抗生素是解决腰椎后路手术患者肠道功能障碍的有效办法。     

Effect of lumbar fasciae on the stability of the lower lumbar spine

The biomechanical effect of tensioning the lumbar fasciae (LF) on the stability of the spine during sagittal plane motion was analysed using a validated finite element model of the normal lumbosacral spine (L4-S1). To apply the tension in the LF along the direction of the fibres, a local coordinate was allocated using dummy rigid beam elements that originated from the spinous process. Up to 10 Nm of flexion and 7.5 Nm of extension moment was applied with and without 20 N of lateral tension in the LF. A follower load of 400 N was additionally applied along the curvature of the spine. To identify how the magnitude of LF tension related to the stability of the spine, the tensioning on the fasciae was increased up to 40 N with an interval of 10 N under 7.5 Nm of flexion/extension moment. A fascial tension of 20 N produced a 59% decrease in angular motion at 2.5 Nm of flexion moment while there was a 12.3% decrease at 10 Nm in the L5-S1 segment. Its decrement was 53 and 9.6% at 2.5 Nm and 10 Nm, respectively, in the L4-L5 segment. Anterior translation was reduced by 12.1 and 39.0% at the L4-L5 and L5-S1 segments under 10 Nm of flexion moment, respectively. The flexion stiffness shows an almost linear increment with the increase in fascial tension. The results of this study showed that the effect of the LF on the stability of the spine is significant.     

Morphological and functional differentiation in the lumbar spine of lorisids and galagids

The striking contrast in positional behavior exhibited by lorisids (slow quadrupedalism/suspension) and galagids (leaping/quadrupedalism) is well reflected in their postcranial morphology, particularly in the limbs. Although they exhibit very different spinal postures and movements, vertebral adaptations have been less well explored in these taxa. This study addressed morphological and functional differentiation in the lumbar vertebrae of four species of lorisids and five species of galagids. Linear and angular measurements of lumbar vertebrae were compared among taxa using canonical variates analysis (CVA) in conjunction with pairwise comparisons among selected variables. The results were interpreted in the context of a broader comparative sample, including the addition of indriids to the CVA. Compared to galagids, lorisids have relatively shorter lumbar spinous processes that are more perpendicularly (to caudally) oriented relative to a coronal plane. Lorisids also have relatively wider laminae and more transversely oriented prezygapophyses. These features promote lumbar stability and reflect antipronogrady, multiplane spinal movements, and upside-down suspension. Within lorisids, vertebral body length and height vary with body size, reflecting the additional resistance to bending that is required for larger body sizes. Galagid lumbar shape is influenced by body size, but does not show strong variation in accordance with positional behavior differences as defined here. Galagids, indriids, and lorisids are distinct in lumbar morphology and function, but their similarities in lumbar length reduction are suggestive of antipronograde postures in the common ancestor of the galagids, including those who have shifted to a more quadrupedal locomotor repertoire.     

Increase in facet joint loading after nucleotomy in the human lumbar spine

Low-back pain has been related to degenerative changes after nucleotomy. Although several etiologies for pain after nucleotomy have been proposed, there is evidence of pain arising in the facet joints in general, which may be related to changes in load transfer. This study addresses the effect of nucleotomy on facet joint loading.     

Twente spine model: A complete and coherent dataset for musculo-skeletal modeling of the lumbar region of the human spine

Musculo-skeletal modeling can greatly help in understanding normal and pathological functioning of the spine. For such models to produce reliable muscle and joint force estimations, an adequate set of musculo-skeletal data is necessary. In this study, we present a complete and coherent dataset for the lumbar spine, based on medical images and dissection measurements from one embalmed human cadaver. We divided muscles into muscle-tendon elements, digitized their attachments at the bones and measured morphological parameters. In total, we measured 11 muscles from one body side, using 96 elements. For every muscle element, we measured three-dimensional coordinates of its attachments, fiber length, tendon length, sarcomere length, optimal fiber length, pennation angle, mass, and physiological cross-sectional area together with the geometry of the lumbar spine. Results were consistent with other anatomical studies and included new data for the serratus posterior inferior muscle. The dataset presented in this paper enables a complete and coherent musculo-skeletal model for the lumbar spine and will improve the current state-of-the art in predicting spinal loading.     

Micro-CT检测中等强度跑台运动对去卵巢大鼠腰椎微结构的影响

目的用micro-CT方法,评估中等强度跑台运动对去卵巢大鼠腰椎微结构的影响。方法将30只3月龄雌性SD大鼠按体重分层后随机分为假手术、去卵巢静止和去卵巢运动三个组。运动组每周进行4次45min、速度18 m/min、坡度5°的跑台训练。正式运动处理14周时,取第2腰椎检测骨密度,取第4腰椎行micro-CT分析及三维结构重建;取第3腰椎椎体进行椎体压缩实验。结果去卵巢运动组第2腰椎骨密度、第3腰椎最大载荷、最大应力和弹性模量以及第4腰椎骨小梁体积和骨小梁数目显著高于去卵巢静止组,骨小梁分离度显著低于去卵巢静止组,而骨小梁厚度无显著变化。结论中等强度跑台运动能改善去卵巢大鼠腰椎的微结构。     

Statistical shape modeling characterizes three-dimensional shape and alignment variability in the lumbar spine

The mechanics of the lumbar spine are heavily dependent on the underlying anatomy. Anatomical measures are used to assess the progression of pathologies related to low back pain and to screen patients for surgical treatment options. To describe anatomical norms and pathological differences for the population, statistical shape modeling, which uses full three-dimensional representations of bone morphology and relative alignment, can capture intersubject variability and enable comparative evaluations of subject to population. Accordingly, the objective of this study was to develop a comprehensive set of three-dimensional statistical models to characterize anatomical variability in the lumbar spine, by specifically describing the shape of individual vertebrae, and shape and alignment of the entire lumbar spine (L1-S1), with a focus on the L4-L5 and L5-S1 functional spinal units (FSU). Using CT scans for a cohort of 52 patients, lumbar spine geometries were registered to a template to establish correspondence and a principal component analysis identified the primary modes of variation. Scaling was the most prevalent mode of variation for all models. Subsequent modes of the statistical shape models of the individual bones characterized shape variation within the processes. Subsequent modes of variation for the FSU and entire spine models described alignment changes associated with disc height and lordosis. Quantification of anatomical variation in the spine with statistical models can inform implant design and sizing, assist clinicians in diagnosing pathologies, screen patients for treatment options, and support pre-operative planning.     

Adaptation of a clinical fixation device for biomechanical testing of the lumbar spine

In-vitro biomechanical testing is widely performed for characterizing the load-displacement characteristics of intact, injured, degenerated, and surgically repaired osteoligamentous spine specimens. Traditional specimen fixture devices offer an unspecified rigidity of fixation, while varying in the associated amounts and reversibility of damage to and “coverage” of a specimen – factors that can limit surgical access to structures of interest during testing as well as preclude the possibility of testing certain segments of a specimen. Therefore, the objective of this study was to develop a specimen fixture system for spine biomechanical testing that uses components of clinically available spinal fixation hardware and determine whether the new system provides sufficient rigidity for spine biomechanical testing. Custom testing blocks were mounted into a robotic testing system and the angular deflection of the upper fixture was measured indirectly using linear variable differential transformers. The fixture system had an overall stiffness 37.0, 16.7 and 13.3 times greater than a typical human functional spine unit for the flexion/extension, axial rotation and lateral bending directions respectively – sufficient rigidity for biomechanical testing. Fixture motion when mounted to a lumbar spine specimen revealed average motion of 0.6, 0.6, and 1.5° in each direction. This specimen fixture method causes only minimal damage to a specimen, permits testing of all levels of a specimen, and provides for surgical access during testing.     

Functional aspects of strepsirrhine lumbar vertebral bodies and spinous processes

The relationship between form and function in the lumbar vertebral column has been well documented among platyrrhines and especially catarrhines, while functional studies of postcranial morphology among strepsirrhines have concentrated predominantly on the limbs. This morphometric study investigates biomechanically relevant attributes of the lumbar vertebral morphology of 20 species of extant strepsirrhines. With this extensive sample, our goal is to address the influence of positional behavior on lumbar vertebral form while also assessing the effects of body size and phylogenetic history. The results reveal distinctions in lumbar vertebral morphology among strepsirrhines in functional association with their habitual postures and primary locomotor behaviors. In general, strepsirrhines that emphasize pronograde posture and quadrupedal locomotion combined with leaping (from a pronograde position) have the relatively longest lumbar regions and lumbar vertebral bodies, features promoting sagittal spinal flexibility. Indrids and galagonids that rely primarily on vertical clinging and leaping with orthograde posture share a relatively short (i.e., stable and resistant to bending) lumbar region, although the length of individual lumbar vertebral bodies varies phylogenetically and possibly allometrically. The other two vertical clingers and leapers, Hapalemur and Lepilemur, more closely resemble the pronograde, quadrupedal taxa. The specialized, suspensory lorids have relatively short lumbar regions as well, but the lengths of their lumbar regions are influenced by body size, and Arctocebus has dramatically longer vertebral bodies than do the other lorids. Lumbar morphology among galagonids appears to reflect a strong phylogenetic signal superimposed on a functional one. In general, relative length of the spinous processes follows a positively allometric trend, although lorids (especially the larger-bodied forms) have relatively short spinous processes for their body size, in accordance with their positional repertoire. The results of the study broaden our understanding of postcranial adaptation in primates, while providing an extensive comparative database for interpreting vertebral morphology in fossil primates.     

Kinematics and muscle activities of the lumbar spine during and after working in stooped postures

Existing biomechanical evidence suggests mechanisms of low back injuries and disorders associated with prolonged stooping. However, no research has tested realistic and more natural stooped work conditions with human subjects in the investigation of the biomechanical responses of the low back in prolonged stooping. The current study was aimed to explore various biomechanical responses of the low back in more realistic and work-related loading and posture conditions of prolonged stooping. Twenty two subjects performed stooped work tasks for 7 min with periodic micro-breaks in upright standing, and various measures for assessing biomechanical responses of the low back were obtained before, during and immediately after the stooped work period. Study results found significant increases (p < 0.05) in the range of lumbar flexion and myoelectric activation of the low back muscles after the stooped work period. During stooped work, the low back extensor muscles did not show flexion–relaxation. It could be concluded that the natural and unrestricted stooped work conditions produced similar viscoelastic responses of the low back to what more severe stooping conditions with posture restrictions did in previous research, but could be more fatigue-prone due to low but consistent activation of the low back extensor muscles during stooped work activities.     

Sarcomere length organization as a design for cooperative function amongst all lumbar spine muscles

The functional design of spine muscles in part dictates their role in moving, loading, and stabilizing the lumbar spine. There have been numerous studies that have examined the isolated properties of these individual muscles. Understanding how these muscles interact and work together, necessary for the prediction of muscle function, spine loading, and stability, is lacking. The objective of this study was to measure sarcomere lengths of lumbar muscles in a neutral cadaveric position and predict the sarcomere operating ranges of these muscles throughout full ranges of spine movements. Sarcomere lengths of seven lumbar muscles in each of seven cadaveric donors were measured using laser diffraction. Using published anatomical coordinate data, superior muscle attachment sites were rotated about each intervertebral joint and the total change in muscle length was used to predict sarcomere length operating ranges. The extensor muscles had short sarcomere lengths in a neutral spine posture and there were no statistically significant differences between extensor muscles. The quadratus lumborum was the only muscle with sarcomere lengths that were optimal for force production in a neutral spine position, and the psoas muscles had the longest lengths in this position. During modeled flexion the extensor, quadratus lumborum, and intertransversarii muscles lengthened so that all muscles operated in the approximate same location on the descending limb of the force-length relationship. The intrinsic properties of lumbar muscles are designed to complement each other. The extensor muscles are all designed to produce maximum force in a mid-flexed posture, and all muscles are designed to operate at similar locations of the force-length relationship at full spine flexion.     

Sensitivity of lumbar spine response to follower load and flexion moment: finite element study

The follower load (FL) combined with moments is commonly used to approximate flexed/extended posture of the lumbar spine in absence of muscles in biomechanical studies. There is a lack of consensus as to what magnitudes simulate better the physiological conditions. Considering the in-vivo measured values of the intradiscal pressure (IDP), intervertebral rotations (IVRs) and the disc loads, sensitivity of these spinal responses to different FL and flexion moment magnitudes was investigated using a 3D nonlinear finite element (FE) model of ligamentous lumbosacral spine. Optimal magnitudes of FL and moment that minimize deviation of the model predictions from in-vivo data were determined. Results revealed that the spinal parameters i.e. the IVRs, disc moment, and the increase in disc force and moment from neutral to flexed posture were more sensitive to moment magnitude than FL magnitude in case of flexion. The disc force and IDP were more sensitive to the FL magnitude than moment magnitude. The optimal ranges of FL and flexion moment magnitudes were 900–1100 N and 9.9–11.2 Nm, respectively. The FL magnitude had reverse effect on the IDP and disc force. Thus, magnitude for FL or flexion that minimizes the deviation of all the spinal parameters together from the in-vivo data can vary. To obtain reasonable compromise between the IDP and disc force, our findings recommend that FL of low magnitude must be combined with flexion moment of high intensity and vice versa.     

Changes in the lumbosacral angle, sacral inclination and the curvature of the lumbar spine during aging.

Measurements of the curvature of the lumbar spine are useful in the investigations of low back pain. It is unclear whether the degree of lumbar lordosis, sacral inclination and lumbosacral angulation are the same for all normal adults. Radiographic studies were carried out on the lumbar spines of subjects aged 9-61 years. Mean and 95% tolerance ranges of the values of lumbar lordosis, lumbosacral angle and sacral inclination for adult age groups up to the sixth decade are given. The results showed that all three parameters varied steadily with age. The pattern of changes differed in males and females. Females had greater angles than males. Sacral inclination appeared to be a more important determinant of the degree of lumbar lordosis. All three parameters showed a tendency to decrease after the sixth decade. The significance of the findings is discussed.     

Association between long-term exercise loading and lumbar spine trabecular bone score (TBS) in different exercise loading groups

Objective:

To examine whether different exercise loading is associated with lumbar vertebral texture as assessed with Trabecular Bone Score (TBS).

Methods:

Data from 88 Finnish female athletes and 19 habitually active women (reference group) were analyzed. Participants’ mean age was 24.3 years (range 17-40 years). Athletes were divided into five specific exercise loading groups according to sport-specific training history: high-impact (triple jumpers and high jumpers), odd-impact (soccer players and squash players), high-magnitude (power lifters), repetitive impact (endurance runners), and repetitive non-impact (swimmers). TBS-values were determined from lumbar vertebral L1-L4 DXA images. Body weight and height, fat-%, lean mass, isometric maximal leg press force, dynamic peak jumping force and lumbar BMD were also measured.

Results:

Endurance runners’ mean TBS value differed significantly from all other groups being about 6% lower than in the reference group. After controlling for body height, isometric leg press force and fat-%, the variables found consistently explaining TBS, the observed between-group difference remained significant (B=-0.072, p=0.020). After controlling for BMD, the difference persisted (B=-0.065, p=0.016). There were no other significant adjusted between-group differences.

Conclusion:

Exercise loading history comprising several repeated moderate impacts is associated with somewhat lower TBS, which may indicate specific lumbar microarchitecture in endurance runners.     

老年腰椎骨折术后深部切口感染患者病原菌和感染危险因素分析

分析老年腰椎骨折术后切口深部感染患者的病原菌分布特征及感染危险因素,为该类患者的治疗提供参考。

选择2018年2月至2021年2月于我院行腰椎手术治疗且符合纳入标准的患者589例,记录患者感染发生率,并对感染病原菌分布特征及感染的危险因素进行单因素和多因素分析,同时探讨相应对策。

589例腰椎骨折手术患者有41例（6.96%）出现切口深部感染。41例感染患者的渗出液或分泌物中鉴定分离出53株病原菌,其中30例患者为单菌株感染,占73.17%;11例患者为多菌株感染,占26.83%。53株病原菌中革兰阴性菌30株,革兰阳性菌22株,真菌1株。革兰阴性菌中,大肠埃希菌对哌拉西林的耐药率最高,为91.67%;对美罗培南、亚胺培南及厄他培南的耐药率相对较低,为16.67%;铜绿假单胞菌对头孢吡肟、头孢曲松、头孢唑林和复方磺胺甲噁唑的耐药率最高,为90.00%;对环丙沙星和阿米卡星的耐药率相对较低,为20.00%。革兰阳性菌中金黄色葡萄球菌对青霉素和红霉素的耐药率最高,为76.92%;对万古霉素、利奈唑胺的耐药率为0.00%。术后感染患者与非感染患者在年龄分布、BMI、是否合并糖尿病、手术持续时间、是否输血等方面的差异有统计学意义（均P＜0.05）;在性别、是否存在烟酒史、是否合并高血压或冠心病、术中失血量等方面差异无统计学意义（均P＞0.05）。Logistic回归分析显示,年龄≥60岁、BMI≥28 kg/m²、合并糖尿病、手术时间≥2 h及预防性应用抗生素为腰椎骨折术后患者切口深部感染的独立危险因素（均P＜0.05）。

腰椎骨折术后患者深部切口感染病原菌种类较多,以金黄色葡萄球菌和大肠埃希菌为主,且药敏性普遍较低。年龄≥60岁、BMI≥28 kg/m²、合并糖尿病、手术时间≥2 h及预防性应用抗生素为腰椎骨折术后患者切口深部感染的独立危险因素,临床应根据药敏情况合理选择抗菌药物以降低感染发生率。