摘要:

Study DesignThis study analyzed the development of the lumbosacral vertebral canal and dural sac in human fetus. A collection of fetuses and embryos was used to assess the development of different parameters of the spinal canal.ObjectivesThe data were analyzed for the dynamics of development and also compared with mean adult spinal parameters.Summary of Background DataTransversely sectioned specimens and nonsectioned specimens free of abnormalities were selected from the Boyd Collection of human embryos and fetuses.MethodsThe sections were photographed alongside a micrometric scale, and the nonsectioned specimens were scanned by magnetic resonance imaging. The films were computer analyzed for spinal and dural parameters. The error of the measurements was assessed.ResultsThe most rapid growth period of the spinal canal parameters is between 18-36 weeks' gestation. After 30 weeks of intrauterine life, the upper lumbar canal grows faster than the lower lumbar region. The distal end of the dural sac begins to rise from S5 after 14 weeks.ConclusionsAt the end of intrauterine growth, the interpedicular diameter of the spinal canal from L1 to L4 is 70% of the adult size, however, at L5, the canal is only 50% mature at birth. Therefore, if there is growth impairment in early infancy, the upper lumbar region is partially protected in contrast with the L5 level.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignThis anatomic study describes a new intraosseous, posteior approach to the sacroiliac joint.ObjectivesTo define a transosseous approach to the sacroiliac joint in which a triangular bony window is raised on the posterosuperior aspect of the ilium that provides improved access to the sacroiliac joint for posterior fusion.Summary of Background DataA posterior approach to the sacroiliac joint has been widely used for debridement of infectious diseases and for fusion. Most conventional approaches to the sacroiliac joint are interosseous, and there is a relative lack of information on transiliac approaches.MethodsThe projection of the sacroiliac joint on the outer table of the ilium and the thickness of the posterior ilium forming part of the sacroiliac joint were determined in 15 cadaveric pelves. A right angle, triangular bony window was raised from the posterior ilium to investigate the suitability of a transiliac approach in performing sacroiliac debridement and arthrodesis. A horizontal reference line 3-3.5 cm in length was drawn between a point 1 cm anterosuperior to the posteroinferior iliac spine and a point 1.5 cm superior to the superior border of the greater sciatic notch. A vertical reference line was extended superiorly for 2-2.5 cm perpendicular to and beginning at the anterior end of the horizontal reference line. The oblique arm of the right triangle was created by joining the superior end of the vertical reference line to the posterior end of the horizontal line.ResultsThirty percent of fifty percent of the articular surface of the iliac bone was removed with this triangular segment of bone, and a corresponding area of the sacral articular surface was visualized directly. It was possible to remove the rest of the articular cartilage with angled curettes in all specimens.ConclusionsThis approach facilitates improved access to the sacroiliac joint for debridement and arthrodesis with minimal soft tissue dissection and iliac bone resection.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignThree types of porous ceramic bone graft substitutes were used for anterior interbody fusion in the canine thoracic spine.ObjectivesTo compare the biomechanical stiffness and histologic appearance of fused spinal segments using ceramic graft substitutesversusautogenous bone graft.Summary of Background DataThe relative success or failure of ceramic grafts is influenced by many variables, including the composition of the ceramic, location in the spine, stability, and the animal model used.MethodsFour experimental groups were evaluated: autogenous tricortical iliac crest (n = 6); hydroxyapatite ceramic (Interpore-200; n = 6); biphasic (60: 40) hydroxyapatite/tricalcium phosphate ceramic (Zimmer; n = 4); and calcium carbonate ceramic (Inoteb; n = 4). All dogs were killed 8 weeks after surgery. After postmortem removal of anterior spinal instrumentation, the spinal segments underwent nondestructive biomechanical testing and light microscopic histologic evaluation.ResultsBiomechanical testing showed that spines from the autogenous tricortical iliac crest group were statistically significantly stiffer in flexion, extension, left and right bending, and torsion than all ceramic groups. No differences in stiffnesses were observed among the three ceramic groups. Histologically, the autogenous tricortical iliac crest graft performed best, with osseous union at 10 of 12 interfaces. Of the ceramic grafts, hydroxyapatite/tricalcium phosphate and calcium carbonate demonstrated more consistent junction healing than the hydroxyapatite group, where four of 12 interfaces resulted in a nonunion. In the ceramic groups, a variable amount of revascularization and new bone was observed within the grafts.ConclusionsAutogenous iliac crest bone graft provides superior healing in this anterior spine fusion model. Additional investigation is needed before ceramic grafts can be considered satisfactory alternatives to anterior autogenous bone grafts.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignRepeatedin vitromechanical tests were performed on porcine and human interspinous ligament specimens with progressive disruption of the collagen fiber network to evaluate the existence of mechanical interactions between collagen fibers.ObjectiveTo evaluate the existence of a load pathway in the interspinous ligament whereby loads are transmitted between collagen fibers.Summary of Background DataMechanical tests demonstrate that the interspinous ligament resists spinal flexion, but the collagen fibers are not oriented to oppose separation of the spinous processes. This seeming contradiction could be explained by the existence of mechanical interactions between collagen fibers of the interspinous ligament.MethodsIn vitromechanical tests were performed on porcine and human bone-interspinous ligament-bone specimens. The collagen network of the ligament substance was disrupted by passing a scalpel blade though the ligament substance. Repeated tests were performed with progressive disruption of the collagen fiber network.ResultsThe stiffness of the interspinous ligament specimens was reduced as the collagen fiber network was disrupted, but approximately half of the initial stiffness was maintained when the collagen fiber network was severely disrupted. In this case, no intact collagen fibers remained.ConclusionsMechanical interactions exist between collagen fibers in the interspinous ligament. The mechanism of the interactions is unknown.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignThe advantage to fixation strength of triangulated, double-screw fixation compared with that of single-screw instrumentation in anterior spine surgery was evaluated byin vitrotesting.ObjectivesTo compare the fixation strength of single-screw instrumentation with ventral derotation spondylodesis screws with the fixation strength of triangulated, double-screw instrumentation with Cotrel-Dubousset-Hopf screws. Resistance against pull-out load and against load perpendicular to the axis of the screws was evaluated. To avoid the bias caused by different screw design, the pull-out strength of single screws of both devices was compared first.Summary of Background DataTo the authors' knowledge, no study comparing anterior single with triangulated screws has been published.MethodsA pull-out test was performed when one vertebra in each spine specimen was instrumented with a ventral derotation spondylodesis screw, one with an isolated Cotrel-Dubousset-Hopf screw, and one with two triangulated, Cotrel-Dubousset-Hopf screws linked by a Cotrel-Dubousset-Hopf block. Load perpendicular to the axis of the screw was applied on the bone-device interface after instrumentation of further specimens with ventral derotation spondylodesis and triangulated, Cotrel-Dubousset-Hopf devices.ResultsUse of isolated Cotrel-Dubousset-Hopf screws compared with ventral derotation spondylodesis screws showed no significant differences in pull-out strength. The use of triangulated, double-screw fixation with Cotrel-Dubousset-Hopf screws led to a significant 79% increase in resistance against pull-out and a 73% increase in resistance against load perpendicular to the screw axis compared with the resistance produced using ventral derotation spondylodesis single-screw instrumentation.ConclusionIn anterior surgery, fixation of the vertebra-device interface can be improved considerably by application of two triangulated screws.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study designEmpirical studies concerning the whiplash syndrome are reviewed from the point of view of epidemiologic methodology.ObjectiveTo assess the nosologic status of the whiplash syndrome.Summary of background dataAlthough a large number of studies concerning the syndrome exist, there is still controversy concerning the existence of the syndrome.MethodsThe manner in which each study contributes to the validity of the syndrome is determined on the basis of the methodologic design (descriptive, case-control, cohort, and intervention/experimental) of the study.ResultsWhereas the face validity of the syndrome is excellent, the descriptive, construct, and predictive validity are rather poor. In particular, convincing empirical evidence for a causal link (construct validity) between the trauma mechanism and chronic symptoms is sparse.ConclusionsCarefully conducted studies designed to assess the degree to which head and neck trauma contribute to the development of chronic pain, particularly head and neck pain, are urgently needed.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignA cross-sectional design was used to correlate cervical radiographic findings of spinal degeneration to neck pain and disability.ObjectivesThe results were correlated to assess the clinical importance of radiographic spinal degeneration.Summary of Background DataPast investigations suggest little association between clinical findings and radiographic evidence of spinal degeneration. However, changes in activities of daily living and chronicity of complaint have not been investigated.MethodsOver a 5-month period, data were collected on 700 consecutive patients referred for cervical radiographic examination as part of their clinical evaluation. While in the radiology department, all subjects completed a visual analog pain scale, neck disability index, and short questionnaire, all of which quantified various aspects of any neck complaint. Relationships between indices of patient complaint and the number of cervical degenerative intervertebral discs were evaluated using regression analysis.ResultsA significant relationship (P< 0.001) was noted between the number of levels of intervertebral disc degeneration and the chronicity of cervical complaint. No significant relationship was found between cervical degeneration and past trauma (P= 0.904) or gender (P= 0.213). Multiple-regression analysis of visual analog pain scale scores revealed a significant two-way interaction with chronicity and past trauma (P= 0.007) and a significant main effect with gender (P< 0.001). Cervical degeneration was not significant as a main effect or interaction with other factors. Multiple-regression analysis of neck disability index scores demonstrated a significant three-way interaction of chronicity, degeneration, and gender (P= 0.022) and a significant two-way interaction for chronicity and trauma (P= 0.025). No additional information was gathered by multivariate multiple-regression techniques.ConclusionsIncreasing levels of spinal degeneration are related to increasing chronicity of patient complaints. Spinal degeneration is not related to past trauma or gender. Women, but not men, report higher disability with increasing levels of degeneration. Subjects with past trauma reported more intense pain and disability. Overall, men reported less neck pain and disability than women.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study designMagnetic resonance images were obtained of the lumbar spines of three volunteers in neutral, flexed, and extended postures.ObjectivesTo measure migration of the nucleus pulposus within the intervertebral disc during flexion and extension of the spine in living people.Summary of Background DataResults of experiments on bisected cadaveric spines have indicated that the nucleus migrates posteriorly during flexion and anteriorly during extension in nondegenerate discs. Degenerate discs may have faults or fissures that result in abnormal motion of the nucleus.MethodsProton density weighted, sagittal, magnetic resonance images were obtained from the lumbar spines of three volunteers. Measurements of the positions of the anterior and posterior margins of the nucleus and of flexion and extension angles were made on tracings of the images corresponding to neutral, flexed, and extended postures.ResultsThe observed frequency (22 of 24 measurements) at which the margins of the nucleus migrated in the directions predicted by results of cadaveric studies was significantly greater than the frequency that would be expected by chance (P< 0.001). The two exceptions may be a result of disc degeneration. There was a significant (P< 0.05) linear correlation between the migration of the anterior margin and the flexion-extension angle and a highly significant (P< 0.001) correlation for the posterior margin and the flexion-extension angle.ConclusionsFlexion of an intervertebral disc in a living person tends to be accompanied by posteriorly directed migration of the nucleus pulposus within the disc. Extension tends to be accompanied by an anteriorly directed migration.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignThe study compared the presence of the high-intensity zone on magnetic resonance imaging with the results of awake discography.ObjectivesTo see if there was a correlation between the results of awake discography and the presence of a high-intensity zone on magnetic resonance imaging.Summary of Background DataThe evaluation of discogenic pain has proved to be somewhat elusive. Recent studies have indicated the high-intensity zone as being highly sensitive in the diagnosis of the painful discogenic segment. The present study was designed to investigate whether the presence of a high-intensity zone is associated with a concordant pain response on awake discography.MethodsMagnetic resonance images were obtained in 29 patients with low back pain with and without radiculopathy. Consecutive patients were considered for surgical intervention after failing to respond to conservative treatment. The presence of a high-intensity zone was specifically looked for within the posterior anulus. Each patient subsequently underwent awake discography with computed tomography. Computed tomography was classified according to the Dallas Discogram Scale and the presence of a concordant pain response. Chi-square analysis was used to calculate the presence of a high-intensity zoneversusdisc disruption and the correlation of high-intensity zone and concordant pain response.ResultsThere was no statistically significant correlation between the presence of a high-intensity zone and a concordant pain response at any level. The high-intensity zone was, however, never seen in a morphologically normal disc.ConclusionsAlthough the high-intensity zone is present within the posterior anulus of some abnormal discs, it is not necessarily associated with a concordant pain response.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID