摘要:

Study DesignTo use fresh, human supraspinal and interspinal ligments and document their innervation.ObjectivesTo characterize the innervation of the human supraspinal and interspinal ligaments.Summary of Background DataThe nature and distribution of the innervation of spinal ligaments remains unknown.MethodsSections of spinal ligaments were labeled with a fluorescent antibody against neurofliament proteins and observed with a confocal microscope.Results.The ligaments were found to be well innervated. Innervation was equally distributed along the ligament, symmetrically distributed between left and right sides, and more densely distributed in the periphery. Pacinian corpuscles were scattered randomly, close to blood vessels, whereas Ruffini corpuscies were in the periphery, close to the collagen bundles.ConclusionsHuman supraspinal and interspinal ligaments are well innervated. This innervation might from the basis of neurologic feedback mechanisms for the protection and stability of the spina. These mechanisms might also be important in the development of diseases such as scoliosis.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study DesignPosterior lumbar spinal fusion segments were evaluated in 9 adult mongrel dogs 6, 12, and 26 weeks after implantation. Four sites on each animal received implants consisting of demineralized bone matrix alone, demineralized bone matrix with allograft bone, allograft bone alone, and autograft bone. Each unilateral fusion spanned one motion segment with one intervening vertebral level left undisturbed using T13-L7. The fusions were evaluated radiographically, mechanically, and histologically.ObjectiveThe purpose of this study was to determine the efficacy of demineralized bone matrix as a bone graft substitute for stable posterior spinal fusion.Summary of Background DataPosterior spinal fusion is a procedure commonly performed for spinal stabilization. Increasing the incidence and speed of stable spinal fusion is a primary goal in spinal surgery. Concerns have developed regarding the graft material used to induce bone healing at the fusion site. The advent of osteoinductive materials, such as demineralized bone matrix, may eliminate the need to harvest autograft bone and may circumvent the immunologic responseand lower osteogenic potential associated with allograft bone.MethodsThe quality of fusion and new bone formation was evaluated radiographically using plain films, computed tomography, and magnetic resonance imaging. After the dogs were killed, each fusion segment was evaluated mechanically in torsion to determine stiffness and histologically to determine qualitative parameters of new bone formation and remodeling.ResultsRadiographic studies showed that autograft bone sites achieved stable fusion by 26 weeks after surgery. Conversely, the demineralized bone matrix alone and with allograft bone demonstrated some new bone formation at 6 and 12 weeks, but did not achieve fusion by 26 weeks. The fusion sites of allograft bone alone showed minimal new bone formation at all time periods. Mechanically, the autograft fusion sites demonstrated torsional stability that was significantly greater than that of all other fusion sites at all time periods. The remaining fusion sites showed equivalent torsional stiffness at all time periods. Histologic analysis confirmed the radiographic and mechanical findings.ConclusionsThe results indicate that demineralized bone matrix alone or with allograft bone is ineffective in achieving stable posterior spinal fusions.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study DesignThe issue of segmental stability using finite element analysis was studied. Effect of ligament and facet (total and partial) removal and their geometry on segment response were studied from the viewpoint of stability.ObjectivesTo predict factors that may be linked to the cause of rotational instabilities, spondylolisthesis, retropondylolisthesis, and stenosis.Summary of Background DataThe study provides a comprehensive study on the role of facets and ligaments and their geometry in preserving segmental stability. No previous biomechanical study has explored these issues in detail.MethodsThree-dimensional nonlinear finite element analysis was performed on L3-L4 motion segments, with and without posterior elements (Ligaments and facets), subjected to sagittal moments. Effects of ligament and facet (partial and total) removal and their orientations on segment response are examined from the viewpoint of stability.ResultsLigaments play an important role in resisting flexion rotation and posterior shear whereas facets are mainly responsible for preventing large extension rotation and anterior displacement. Facet loads and stresses are high under large extension and anterior shear loading. Unlike total facetectomy, selective removal of facets does not compromise segmental stability. Facet loads are dependent on spatial orientation.ConclusionsRotational instability in flexion or posterior displacement [retrospondylolisthesis) is unlikely without prior damage of ligaments, whereas instability in extension rotation or forward displacement (spondylolisthesis) is unlikely before facet degeneration or removal. The facet stress and displacement distribution predicts that facet osteoerthritis or hypertrophy leading to spinal stenosis is most likely under flexion-anterior shear loading,Selective facetectomy may restore spinal canal size without compromising the stability of the segment. A facet that is more sagittally oriented may be linked to the cause of spondylolisthesis, whereas a less transversely oriented facet joint may be linked to rotational instabilities in extension.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study DesignThe nerve root of L7 was exposed, and a clamp was applied to simulate radiculopathy. In traradicular blood flow was measured at the takeoff point of the nerve root and at the distal to the dorsal root ganglion before and after nerve root infiltration with 2% lidocaina or physiological saline solution (control group),or sympathetic ganglion block with 2% lidocaine,ObjectivesTo investigate one of the mechanisms of the therapeutic effect of nerve root infiltration by assessing changes in intraradicular blood flow.Summary of Background DataIncreased intraradicular blood flow was noted both proximal and distal to the clamp after nerve root infiltration or sympathetic ganglion block with 2% lidocaine. No increase was seen after nerve root infiltration with saline solution,Macroscopic and microscopic examination showed that dye after nerve root infiltration did not spread beyond the clamped region to the proximal site.MethodsIntraradicular blood flow was measured with a tissue blood flowmeter using the electrolytic hydrogen clearance method before and after nerve root infiltration with 2% lidocaine or physiologic saline solution (control group), or sympathetic ganglion block with 2% lidocaine.ResultsIncreased intraradicular blood flow was noted both proximal and distal to the clamp after nerve root infiltration or sympathetic ganglion block with 2% lidocaine. No increase was seen after nerve root inflitration with saline solution.ConclusionsAn increase in intraradicular blood flow is related to one of the mechanisms of the therapeutic effect of nerve root infiltration. This effect may be mediated by the sympathetic nervous system.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study designA prospective cross-sectional analytic study.ObjectivesTo assess in patients with chronic low back pain whether the presence or absence of pain originating from the lumbar zygapophysial joints correlates with changes seen on computed tomography.Summary of Background DataResults of studies have been divided as to whether or not radiologic imaging is able to predict those patients with pain originating from the zygapophysical joints.MethodsSixty-three patients with low back pain lasting for longer than 3 months underwent computed tomography and blocks of the zygapophysial joints at L5-S1,L4-L5, and L3-L4. The zygapophysical joints of all images were scored by three independent, masked radiologists.ResultsInterobserver agreement was poor with intraclass correlation coefficients of 0.34–0.66 using total joint scores for all three assessors. Using the results of a repeat assessment with two radiologists there was no statistically significant difference in joint scores between those with and those without pain originating from the zygapophysial joint.ConclusionsComputed tomography has no place in the diagnosis of lumbar zygapophysial joint pain.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study DesignMeasured trunk muscle activity was employed in a biomechanical model to determine the influence of including or neglecting muscle coactivity on predicted spinal loads.ObjectivesThe purpose of this investigation was to examine the influence of muscle coactivity on spinal load.Summary of Background DataElectromyographic patterns in the trunk musculature have demonstrated significant levels of cocontraction during lifting exertions. Biomechanical analyses of musculoskeletal loading are often mathematically constrained from including muscle coactivity. Models that attempt to include coactive behavior are complex and difficult to implement.MethodsElectromyographic data were collected from five trunk muscle pairs while subjects performed dynamic lifting excertions. A validated, electromyographically assisted biomechanical model was used to compute relative muscle force, lifting moment, and spinal load. Results were generated and compared from analyses that included from one to five simultaneously active muscle pairs.ResultsTrunk extensor muscles generate lifting moments as much as 47% greater than the applied lifting moment to offset flexor antagonism. Analyses that neglect muscle coactivity during dynamic lifting exertions may underestimate spinal compression by as much as 45% and shear forces by as much as 70%.ConclusionsThe level of coactive spinal loading is significantly influenced by the weight of the lifted load as well as trunk extension velocity. Muscle coactivity significantly influences the modeled load in the lumbar spine during lifting exertions as should be considered if an accurate measure of spinal loading of desired.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study DesignThis cohort study examined a sample (n = 152) of subjects tested for isokinetic lumbar strength and endurance, using novel endurance measures.ObjectivesTo validate a new lumbar sagittal isokinetic endurance testing protocol comparing reliability in a normal subject cohort with strength test reliability to include presentation of a gender-specific normative database, and then correlating the results to a Sorenson isometric endurance protocol.Summary of Background DataThe isometric Sorenson test has been virtually the only validated clinical tool for lumbar extensor trunk muscle endurance testing, using an exercise chair and permitting the subject to maintain the trunk horizontal against gravity for a single timed contraction. Alternative isokinetic sagittal lumbar performance measurement methodology has been developed recently to measure trunk muscle endurance by determining declining work performance on repeated, reciprocal dynamic contractions.MethodWe compared protocols, performance measures, normative data, and reliability for the static isometric Sorenson test to three different isokinetic endurance measurements: the endurance ratio, final fatigue ratio, and recovery ratio. Subjects were tested on a sagittal Cybex TEF (Lumex, Inc., Ronkonkoma, NY) unit for a strength trial followed by an endurance trial. Subgroups also performed reliability and isometric endurance protocols.ResultsWe found an extremely low test-retest correlation for the isometric Sorenson trunk extension test. All test-retest correlations for the corresponding isokinetic endurance measures were significant and markedly higher. Extensor muscle performance declined more substantially on all endurance measures than flexors and showed more variability. In contrast, trunk strength measures were more reliable and less variable than corresponding endurance measures. Moreover, correlations between the isometric Sorenson test and the isokinetic endurance measures were all negative; i.e., increases in Sorenson time are moderately correlated to greater decline in work performance.ConclusionsReliability of the Sorenson isomatric endurance test is unacceptably low, showing negative correlations to all isokinetic endurance tests for lumbar extensors. Isokinetic strength and endurance tests are far more reliable than isometric tests, with normative data showing more consistent results from men than women. Both genders display more substantial fatigue (and greater variability) in extensor endurance compared with flexor testing. Endurance measures are identified as human performance cognitive constructs, and reasons for greater variability than usually shown by trunk strength measurements are discussed.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study DesignDescriptive epidemiologic study about magnetic resonance imaging findings in the spine.ObjectivesTo describe the prevalence of magnetic resonance imaging findings in a general population at spinal levels T6-S1, and to examine the relationships of these findings within each spinal level and between levels.Summary of Background DataThe prevalence of specific findings and the associations between findings and spinal levels can provide general insights into the etiopathogenesis of spinal degeneration.MethodsSubjects consisted of 232 men from a population sample (mean age 49.3 years). Signal intensity, disc bulging, disc herniation, and endplate irregularities were among 11 findings assessed from magnetic resonance images.ResultsThe disc signal intensities were assessed to be lowest in the lumbar and middle thoracic regions. Disc bulging and disc height narrowing were most common in the lower levels of both the thoracic and lumbar regions. All magnetic resonance imaging findings except herniations and endplate irregularities were clearly associated with age. Osteophytes were most highly associated with disc bulging in levels T6-L3, and with endplate irregularities in the lower lumbar levels. Disc herniations were not consistently associated with any other findings. The disc levels that most highly correlated are grouped as follows: T6-T10, T10-L4, and L4-S1.ConclusionsWith the exception of endplate irregularities and herniations, the magnetic resonance imaging findings appeared to be associated with the same pathogenic process. The interaction of mechanical factors and spinal structures varies between spinal levels, and the degeneration common in the lower parts of the thoracic and lumbar spine could be an outcome of vulnerability for torsional forces. Some gross guidelines for grouping findings can be drawn from disc level correlations.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study DesignThis study directly measured the dimensions of the first sacral vertebra based on dry bony specimens.ObjectivesTo measure the dimensions of the S1 pedicle, vertebral body, and spinal canal, and determine the projections of the S1 pedicle on the posterior aspect of the sacrum.Summary of Background DataSacrel screw fixation remains a challenging clinical problem because of the unique anatomy of the first sacral vertebra. The anatomic data of S1 have rarely been described in the literature.MethodsSacrums from 50 carefully prepared bony spines were used. Linear measurements included the dimensions of the vertebral body, spinal canal, and pedicle. Pedicle width was measured in two segments, pedicle zones 1 and 2. Angular measurements of the pedicle relative to the sagittal plane were also included.ResultsIn pedicle zone 1, the average medial angle of the pedicles was 10.2° for men and 10.7° for women, average width was 10.9 mm for men and 10.4 mm for women, average length of the pedicles was 34.6 mm for men and 34.9 mm for women. In pedicle zone 2, the average medial angle of the pedicles was 39.4° for both men and women, average width was 15.6 mm for men and 14.7 mm for women, average length of the pedicles was 43.7 mm for men, and 41.7 mm for women. The projections of pedicle zones 1 and 2 on the posterior aspect of S1 were determined.ConclusionsThe investigators proposed the concept of pedicle zones 1 and 2. The safer area for S1 pedicle screw insertion was found in pedicle zone 2.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID