ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study Design.While the gross anatomy of the second cervical vertebra has been well described qualitatively, our evolving understanding of spinal pathology makes it necessary for the modern surgeon to have more quantitative information.Objectives.The authors' goal was to directly measure clinically relevant dimensions of the second cervical vertebra, using a collection of anatomic specimens. Summary of Background Data. Many existing studies have been based on analysis of radiographic images, which are subject to errors of magnification, rotation, and projection. Several recent studies of dens morphology have been based on direct measurements. These studies in general did not extend to the lateral masses or posterior ring, however.Methods.Direct measurements using digital calipers and goniometer were taken from 51 dried human second cervical vertebrae. The maximum and minimum anteroposterior and lateral diameters of the dens, and the anteroposterior and lateral diameters of the endplate and foramen and were measured. The heights of the dens and superior facet surfaces were measured relative to a plane defined by the anterior-most point of the inferior endplate and the inferior-most points of the inferior facet surfaces.Results.The greatest variation was found in the dens angle, with specimen dens angles ranging from -2° to 42°. The most significant correlations were between the total height of the vertebra and the height to the base of the dens (r2= 0.81), between the total height of the vertebra and the maximum lateral diameter of the dens (r2= 0.77), and between the minimum lateral diameter of the dens and the maximum lateral diameter of the dens (r2= 0.63).Conclusions.The dimensions measured in this study confirm a significant degree of anatomic variation in the second cervical vertebra, and show no important correlations among the various measured dimensions. In particular, no significant correlation was found between dens height and canal diameter. Dens angle in the sagittal plane was the most variable measurement.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study Design.A simulation study of compression of vertebral motion segments to failure was performed.Objectives.The aim of this study was to determine whether damage of the motion segment under axial compression can be predicted when the load is quantified by means of the elastic energy storage it causes in the segment.Summary of Background Data.Although in one-cycle loading, motion segment strength can be described by the relationship between the product of the bone density and cross-sectional area of the vertebrae and the maximum force, no single criterion has been found to describe strength in both one-cycle and cyclic compressional loading protocols.Methods.Input data were derived fromin vitrostudies by Hansson et al, Keller et al, and by Brinckmann et al. Elastic energy storage at failure was computed using a three-parameter model for a viscoelastic solid with a nonlinear initial response, and related to the product of the bone density and cross-sectional area.Results.The relationship of the product of density and area with the elastic energy appeared to be accurately described by a curvilinear equation. This relationship accounted for 65-93% of the variance in maximum energy. Generalizability of the relationship from cyclic axial loading to one-cycle axial loading was successfully tested.Conclusion.The results of the present study have shown that one criterion suffices to describe the strength of the motion segment in different compressional loading modes.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study Design.Anin vitrostudy to determine the intradiscal pressure changes during flexion in levels above a simulated fusion was performed.Objectives.To determine if intradiscal pressure increases more during flexion in discs above an instrumented spinal segment compared to an uninstrumented segment.Summary of Background Data.The progressive degeneration of intervertebral discs adjacent to a fused or fixed segment is a phenomenon that is noted but poorly understood. Intuitively, the degeneration appears to be a function of altered biomechanics of the motion segments in the spine.Methods.Two intervertebral disc levels were evaluated, L3-L4 and L4-L5 from each of six fresh frozen cadaver spines. Pressure measurements were taken with the spine uninstrumented, with bilateral pedicle screw-rod instrumentation from L5 to S1, and with bilateral pedicle screw-rod instrumentation from L4to S1. Pressure measurements were accomplished with Millar Mikro-Tip pressure transducers. The transducers were placed within the nucleus pulposus of L3-L4 and L4-L5 intervertebral discs. Pressure data were recorded by computer data acquisition. The pressure data were compared by intervertebral level and by the effects of added instrumentation.Results.In general, the addition of instrumentation significantly affected the intradiscal pressure in the levels above a simulated fusion. The intradiscal pressure increased as the amount of levels involved in the simulated fusion increased. The intradiscal pressure increased as flexion motion increased. A greater increase was seen at the L4-L5 level than the L3-L4 level. When L5-S1 fixation was added, the intradiscal pressure increased. When L4-S1 fixation was added, the intradiscal pressure further increased.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study DesignA prospective study of 147 consecutive patients undergoing spinal surgery who were analyzed for response to an effect of an offered autologous blood program.ObjectivesAnalysis of the impact of the autologous program within a comprehensive blood conservation philosophy toward the reduction in the use of homologous blood.MethodsEach patient was prescreened by the autologous program for inclusions and ability. Physical parameters were recorded as were predonation and postdonation hemoglobin levels. The volume of each donation and the number of autologous and homologous units transfused and total operating blood loss were recorded as were complications during donation and transfusion.ResultsOne hundred sixteen of the original one hundred forty-seven patients participated in the program and donated between 150 and 1900 ml of blood during the preoperative period. Of these, 35 patients weighed 45 kg or less. Diagnoses included 97 cases of idiopathic scoliosis and the remainder had spinal deformities of other causes. Of the entire group, 13 patients (11%) received homologous blood transfusion, 7 of these patients had diagnoses other than idiopathic scoliosis.ConclusionsIn this study of 116 patients, 89% of the spinal surgeries were successfully completed using only autologous blood. This compared favorably with a historical control group in which 60% of the patients required homologous blood transfusion. It is concluded that the use of autologous blood donation combined with other blood conservation techniques has significantly lessened the need for homologous transfusion.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study DesignEighty-five patients with adolescent idiopathic scoliosis treated with Milwaukee or thoracolumbosacral orthoses at The Duchess of Kent Children's Hospital were studied longitudinally at 4-6- month intervals until maturity for spinal curvature and vertebral rotation, or until termination of brace treatment for persons who experienced brace failure who went on to have surgery.ObjectivesTo identify radiologic features so that it may be possible to predict outcome of brace treatment early on.Summary of Background DataThe structural curve with poor flexibility and large rotational prominence have been found to be associated with poor prognosis for brace treatment. However, early response to bracing for spinal deformity and its relationship to final outcome of brace treatment in a longitudinal study is not available in the literature.MethodsVertebral rotation and Cobb angles measured from anteroposterior radiographs of the spine obtained before bracing and 1-2 months after bracing were found valuable for prediction. Changes in postbrace Cobb angle and vertebral rotation were considered as an increase or reduction only when there was an increase or reduction of minimum 5° or more from their prebrace measurements.ResultsThose patients who showed increase in vertebral rotation and/or in Cobb angle after brace application were shown to have progression of curves leading to brace failure in 93% of patients, and 79% of these required surgery. The patients with no change in both vertebral rotation and Cobb angle after bracing often experienced brace failure (69%). Two patients (15%) required surgery. The results show that reduction of both Cobb angle and vertebral rotation after application of a brace is a prognostic indicator for a good outcome (97%), and no patients required surgery. Most of the patients with lumbar scoliosis (91%) showed such reductions.ConclusionThe findings show a strong association between changes in vertebral rotation and the Cobb angle after application of a brace and the final outcome. Reduction in both is indicative of a good outcome, whereas increase in one or both indicates brace failure.

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 Design.The aim of 1 his study Is to quantity cliffs run ces between three dimensional rotations in space and their calculated values, either on two-dimensional projections (radiographs or computed tomographic scans) or three-ctimensicnal calculations using various mathematical procedures.Objective.To use a vertebral model to quantify differences between three-dimensional rotations and their calculated values, using two-dimensional projections or various three-dimensional mathematical procedures.Methods.A specific program allowed us to move a geometric vertebral model in space using given values and sequences of lateral, sagittal, and axial rotations. Differences in positions due to differen t sequences were visualized and quantified. Differences due to rotation around global or vertebral axes were considered.Results.For rotations of about 10º, differences are about 2º between three-dimensional and projected angles. Differences increase when combined rotations are large, as generally occurs in a scoliotic spine. They reach 16º for lateral and sagittal rotations of 30º.Conclusion.Axial rotation measured on transverse projection is misleading for vertebrae rotated in space. Moreover, dealing with large three-dimensional rotations is meaningful only if the used mathematical convention is given.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study DesignA prospectively designed study was performed to assess the influence of employment status and a compensation claim on patients experiencing low back pain.ObjectivesTo determine the factor that most influences disability arising from low back pain, unemployment or a compensation claim.Summary of Background DataTwo hundred sixtynine consecutive patients were assessed from a low back pain clinic.MethodsDisability was assessed using the Oswestry Disability Score, and employment, and compensation status were recorded.ResultsBoth unemployment and patients involved in compensation had higher disability scores. However, by controlling the data for employment and assessing only the compensation group it was found that those claiming compensation, but still working had significantly less disability than those claiming compensation who were unemployed.ConclusionsBoth unemployment and compensation claims influence disability, but employment status is the most important factor.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Study Design.A quantitative model of peridural post-laminectomy fibrosis in rats was designed in this study. Concurrently, the effects of a nonsteroidal antiinflammatory drug (ketoprofen) were evaluated.ObjectivesTo quantify the amount of fibrotic tissue, the extent of adhesion to the dura mater, and the cell nature and density for drug trials requiring large series of animals.Summary of Background DataMost of the previous analyses of experimental post-laminectomy fibrosis were qualitative in nature. Only one quantitative analysis was reported in the rabbit, and the rat has seldom been used. The effects of nonsteroidal anti-inflammatory drugs on post-laminectomy scar formation have never been evaluated.MethodsL5 laminectomies were performed in 32 rats. The treated group (16 rats) received a systemic injection of ketoprofen (5 mg/kg, once daily from the day before the operation to the seventh postoperative day), the other 16 rats constituted a control group. The post-laminectomy scar formation was evaluated on postoperative days 8, 15, 30, and 90 using a semiautomatic image analysis system.ResultsThe course of post-laminectomy scar formation was similar to that described in larger animals. There was a good correlation among the measurements of fibrous tissue area obtained by 2 independent observers. The mean amount of peridural scar tissue was significantly smaller in the treated group than in the control group. The extent of adherence to the dura mater and the density of fibroblasts and fibrocytes was not different between the two groups. The density of inflammatory cells was significantly less in the treated group than in the control group only at day 8.ConclusionQuantitative evaluation of post-laminectomy fibrosis can easily be performed in rats and is reproducible. This model could allow trials with drugs administered locally or systemically as preventive treatment of post-laminectomy scar formation. Nonsteroidal anti-inflammatory drugs could decrease the amount of fibrotic tissue.

ISSN:0362-2436    

出版商:OVID    

年代:1995

数据来源: OVID