摘要:

Study Design.Superficial and deep laminae of the posterior layer of lumbar fascia were dissected. The lumbar portion was measured for evidence of segmental thickenings. Superior attachments were dissected, documented, and photographed.Objectives.To verify the existence of posterior accessory ligaments and establish the superior attachments and fiber angles of the posterior layer of lumbar fascia.Summary of Background Data.There have been two small dissection studies on the posterior layer. Their findings are conflicting in several areas of clinical significance. Thickenings in the lumbar region were described in one study, but have not been verified. The superior attachments of the posterior layer have not been formally documented.Methods.Study 1: In 21 embalmed cadavers, the lumbar region of the posterior layer was dissected. The lumbar spinous processes and adjacent fascia were marked. The fascia was removed and examined, and its thickness measured with a manual micrometer. Results were statistically analyzed. Study 2: Superior attachments of the posterior layer in 20 cadavers were dissected and photographed. Capacity to transmit tension was estimated and documented photographically, and fiber angles measuredin situ.Results.Study 1: There was no evidence of macroscopic segmental thickening in the posterior layer. Study 2: The superficial lamina was continuous superiorly with the rhomboids, and the deep lamina with the tendons of splenius cervicis and capitis. These previously undocumented attachments were of variable thickness and fibrosity, and capable of transmitting tension.Conclusions.Both superficial and deep laminae of the posterior layer are more extensive superiorly than previously thought. This may have implications for certain tests used in assessment and management of low back pain such as the slump and “nonorganic” tests. The thickness of the superior attachments is variable. Their capacity for load bearing is yet to be quantified.

ISSN:0362-2436    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Study Design.An analysis of proteoglycans of the intervertebral disc using immunoblotting of tissue extracts.Objectives.To investigate the changes in structure and abundance of fibromodulin and lumican in human intervertebral discs during aging and degeneration.Summary of Background Data.Fibromodulin and lumican are keratan sulfate proteoglycan constituents of the disc’s extracellular matrix, whose interaction with collagen fibrils may contribute to the mechanical properties of the tissue. Changes in their abundance and/or structure that occur with aging and degeneration therefore may have an impact on disc function.Methods.Lumbar intervertebral discs were obtained from individuals of different ages, and extracts of anulus fibrosus and nucleus pulposus were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting using antibodies specific for fibromodulin and lumican.Results.The major changes in abundance observed with age were a decrease in fibromodulin in the adult nucleus pulposus and an increase in lumican in anulus fibrosus during early juvenile development. In addition, fibromodulin in the anulus fibrosus exhibited a structural change with increasing age, characterized by a shift toward the predominance of its glycoprotein form lacking keratan sulfate. Fibromodulin was more abundant in the anulus fibrosus than in nucleus pulposus at all ages, whereas lumican was much more abundant in nucleus pulposus than in anulus fibrosus in the young juvenile; in the adult, however, lumican was present in comparable levels in both tissues. With increasing degrees of degeneration, fibromodulin exhibited an increase in abundance.Conclusions.Growth, aging, and degeneration of the intervertebral disc are associated with changes in the abundance and structure of fibromodulin and lumican, which presumably influence the functional properties of the tissue.

ISSN:0362-2436    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Study Design.Cadaveric study on the biomechanics of osteoporotic vertebral bodies augmented and not augmented with polymethylmethacrylate cement.Objectives.To determine the strength and stiffness of osteoporotic vertebral bodies subjected to compression fractures and 1) not augmented, 2) augmented with unipedicular injection of cement, or 3) augmented with bipedicular injection of cement.Summary of Background Data.Percutaneous vertebroplasty is a relatively new method of managing osteoporotic compression fractures, but it lacks biomechanical confirmation.Methods.Fresh vertebral bodies (L2–L5) were harvested from 10 osteoporotic spines (T scores range, −3.7 to −8.8) and compressed in a materials testing machine to determine intact strength and stiffness. They were then repaired using a transpedicular injection of cement (unipedicular or bipedicular), or they were unaugmented and recrushed.Results.Results suggest that unipedicular and bipedicular cement injection restored vertebral body stiffness to intact values, whereas unaugmented vertebral bodies were significantly more compliant than either injected or intact vertebral bodies. Vertebral bodies injected with cement (both bipedicular and unipedicular) were significantly stronger than the intact vertebral bodies, whereas unaugmented vertebral bodies were significantly weaker. There was no significant difference in loss in vertebral body height between any of the augmentation groups.Conclusions.This study suggests that unipedicular and bipedicular injection of cement, as used during percutaneous vertebroplasty, increases acute strength and restores stiffness of vertebral bodies with compression fractures.

ISSN:0362-2436    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Study Design.A basic science biomechanical study involving an animal model.Objectives.To evaluate the effect of varying angles of halo pin insertion on the force generated at the pin–bone interface, and thereby the stability of the halo pin–bone interaction during insertion.Background Data.Because of variations in the shape and size of the pediatric skull, halo pins often are inserted at various angles rather than perpendicular to the skull. Concern exists that the high complication rate associated with pediatric halo use may result in part from less than ideal structural properties at the halo pin–bone interface.Methods.The authors used a fetal calf skull model to simulate the thickness and structural properties of the pediatric skull. Halo pins were inserted at angles of 0° (perpendicular), 10°, 15°, and 30° into skull segments via a halo ring. Load generated at the pin–bone interface was measured using a modified mechanical testing device. Twenty trials were conducted per angle, with the endpoint being specimen failure, pin penetration, or maximum load.Results.Mean maximum loads per unit thickness were 82.15 ± 7.54 N/mm at 0°, 68.80 ± 4.79 N/mm at 10°, 51.49 ± 5.08 N/mm at 15°, and 42.38 ± 3.51 N/mm at 30°. There was a significant difference between perpendicular insertion (0°) and 15° and 30° angles of insertion. There was also a significant difference between the 10° and 30° angles of insertion.Conclusions.Perpendicular halo pin insertion in an immature skull model was shown to result in increased load at the pin–bone interface. This improved structural behavior may help to reduce the incidence of complications of halo application in children.

ISSN:0362-2436    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Study Design.A cross-sectional retrospective radiologic study.Objectives.To establish concordance rates between interpretations of computed tomography myelography and magnetic resonance imaging in patients with degenerative cervical spine disease.Summary of Background Data.Observed discrepancies in interpretation of computed tomography myelography and magnetic resonance imaging question the reliability of comparisons between these two methods.Methods.This study blindly and randomly evaluated cervical computed tomography myelography and magnetic resonance imaging in 20 patients referred for clinically diagnosed cervical spondylotic radiculopathy, myelopathy, or both. The discovertebral joints, facet joints, lateral recesses, cord size, spinal canal, and neural foramina also were evaluated with graded scales. All results were subjected to the kappa statistic for strength of agreement.Results.Agreement for interpretation of the discovertebral junction occurred in 144 of 240 sites (60%), indicating only moderately good intermethod concordance (&kgr; = 0.44). Intermethod agreement on the characterization of facet joint disease was only moderately good (143 of 160 sites; 89.4%; &kgr; = 0.52), and on characterization of lateral recess disease was poor (125 of 160 sites; 78.1%; &kgr; = 0.20). On degree of spinal canal compromise, there was agreement within one grade in 199 of 240 sites (82.9%; &kgr; = 0.42). Intermethod agreement on neural foraminal encroachment and cord size was only moderately good (&kgr; = 0.42 and 0.46, respectively). Computed tomography myelography tended to upgrade the spinal canal narrowing and neural foraminal encroachment.Conclusions.For most parameters of interpretation, the degree of concordance between computed tomography myelography and magnetic resonance imaging is only moderately good, with discrepancies noted especially in the differentiation of disc and bony pathology. These methods should be viewed as complementary studies.

ISSN:0362-2436    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Study Design.An observational study in which vertebral centroid measurement of lumbar lordosis, developed in this study, was used to examine lumbar curvature. The intra- and interobserver reliability of the vertebral centroid measurement of lumbar lordosis and the Cobb technique were compared.Objectives.To evaluate the reliability of a new method of measuring lumbar lordosis and to examine the changes in the lordotic curve from 0° to 90° flexion of the trunk.Summary of Background Data.Several different methods are used to measure lumbar lordosis. The Cobb technique, based on measurement of vertebral endplates, is the method most frequently adopted for clinical diagnosis. However, because of the variations in the vertebral endplate architecture, the vertebral surface angle is difficult to identify. This reduces the reliability of the Cobb technique.Methods.Lateral radiographs of 16 study participants were taken from the upright position to a trunk flexion of 90° in 30° increments. The lumbar lordotic curve was measured by three observers individually using two applications of the traditional Cobb technique and the vertebral centroid measurement of lumbar lordosis.Results.Correlation coefficients of lumbar lordosis between the two methods ranged from 0.589 to 0.772 with participants standing upright (allP< 0.05). Interobserver reliability coefficients were 0.903 for vertebral centroid measurement of lumbar lordosis, 0.826 for Cobb (L1–L5), and 0.784 for Cobb (L1–S1), although the three measurements all revealed an excellent intraobserver reproducibility (r greater than 0.9). The vertebral centroid measurement of lumbar lordosis showed the smallest mean absolute differences between any two observers’ measurements (< 1.7°).Conclusions.The findings from this study indicate that the vertebral centroid measurement of lumbar lordosis is more reliable than the Cobb method for assessing lumbar lordosis. The vertebral centroid measurement of lumbar lordosis also can be used to evaluate the actual lumbar curvature in outline at various angles of trunk flexion.

ISSN:0362-2436    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Study Design.An investigation of the effects of human trunk extensor muscle fatigue on the temporal change in frequency content of the electromyogram as quantified using the Fourier and wavelet transforms during the performance of repetitive dynamic trunk extension.Objectives.To evaluate whether alterations in the Fourier and wavelet transform measures were consistent with a shift of the signal power to lower frequencies, and to determine which measures were more highly correlated with the decline in maximal trunk extension torque.Summary of Background Data.Objective assessment of trunk muscle fatigue is likely to play a more important role in the rehabilitation and prevention of low back injuries, given the association between lack of trunk muscle endurance and acquisition of low back pain. Validation of new methods designed to quantify the level of fatigue using the surface electromyogram is necessary before these techniques can be used in industrial rehabilitation settings. The wavelet transform is a recent development in the signal processing of electromyograms that shows promise as a method for assessment of fatigue.Methods.Trunk muscle electromyograms obtained from study participants performing repetitive isokinetic trunk extension endurance tests were analyzed using the wavelet and the traditional Fourier methods. Trunk extension torque was controlled at 35% and 70% of the participants’ maximal voluntary contraction while they exerted at 5 and 10 repetitions per minute. The decline in maximal trunk extension torque was measured once per minute. Linear regression quantified the rate of change in Fourier and wavelet measures caused by fatigue, whereas Pearson’s correlation coefficient determined their association with the decline in maximum torque.Results.Changes in the characteristics of the electromyogram were consistent with a shift to lower frequencies: The signal power at higher frequencies was reduced, whereas the power at lower frequencies was elevated. The amount of change was dependent on the task conditions (exertion level and repetition rate). The wavelet-based measures demonstrated as strong an association with the decline in maximal torque output as the Fourier-based measures.Conclusions.This study demonstrates that assessment of trunk muscle fatigue during isokinetic movementis possible using both Fourier and wavelet measures.However, the methods were not as likely to change significantly during lower rates of exertion. These methods, when implemented in a controlled setting, may be used to document the rehabilitation process and guide preventive exercise training.[Key words: dynamic trunk extension, erector spinae, signal processing, time frequency]

ISSN:0362-2436    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Study Design.A comparison of the latencies and amplitudes of the somatosensory-evoked potential in different stages of scoliosis surgery.Objectives.To investigate the normal variability of the somatosensory-evoked potential at different stages of scoliosis surgery and to improve the reliability of spinal cord monitoring.Summary of Background Data.False alarms in intraoperative spinal cord monitoring have been reported when the somatosensory-evoked potential measured before skin incision was used as the reference baseline value. However, the normal variability during different stages of surgery and the specificity of somatosensory-evoked potential is not well documented.Methods.The somatosensory-evoked potential of 90 patients who underwent surgical correction for idiopathic scoliosis was monitored intraoperatively, with stimuli applied to the posterior tibial nerve. The amplitudes and latencies of the somatosensory-evoked potential were recorded over Cz′-Fz and Cv-Fz. The values of latencies and amplitudes and their percentage variabilities were analyzed.Results.The values of latencies and their percentage variabilities did not differ significantly from each other in different stages of surgery. The values of amplitudes between different stages showed statistically significant differences. In particular, the amplitude of the somatosensory-evoked potential was found to be significantly decreased after exposure of the spine when compared with the amplitude before skin incision.Conclusion.Some variability in latencies and amplitudes between different stages of scoliosis surgery is normal. These results suggest that the somatosensory-evoked potential when the spine is exposed may be used as the reference baseline to determine whether somatosensory-evoked potentials are subnormal at the subsequent stages of surgery.

ISSN:0362-2436    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Study Design.A prospective cohort study assessing the responsiveness of two disease-specific questionnaires and a generic health questionnaire for patients with low back pain and sciatica.Objectives.To compare the responsiveness of the eight scales and two summary scales of the SF-36 questionnaire with that of the Oswestry Disability Index and Low Back Outcome Score questionnaires.Summary of Background Data.Evaluation of treatment outcome is being determined more frequently from a patient’s perspective, particularly the impact treatment has on current health status.Methods.Patients were recruited from two orthopedic back pain clinics in a tertiary hospital. Patients completed the pretreatment questionnaire 1 month before treatment and follow-up questionnaires a minimum of 2–6 months after treatment. Patients undergoing surgery were also observed for a minimum of 2 years.Results.Overall, the Oswestry Disability Index was most responsive; however, individual scales from the SF-36 questionnaire showed equal or greater sensitivity to change than the Oswestry Disability Index in each of the patient subgroups. The SF-36 Role Physical scale was prone to floor effects (a high percentage of respondents score zero), and the change scores from the SF-36 Role Emotional scale varied by 100 points in either direction in each of the patient subgroups.Conclusion.Responsiveness varied according to which method was used in its calculation. The responsiveness of the SF-36 questionnaire shows that it can be a useful adjunct in the assessment of patients with low back pain when combined with disease-specific questionnaires. [Key words: Low Back Outcome Score, low back pain, Oswestry Disability Index, outcome measures, responsiveness, SF-36]

ISSN:0362-2436    

出版商:OVID    

年代:1999

数据来源: OVID

摘要:

Study Design.The prevalence of low back pain in the older population (≥ 65 years) was reviewed in an analysis of the literature from 1966 to the present.Objective.To determine the prevalence of low back pain in the geriatric population.Summary of Background Data.Back pain is one of the most frequently reported conditions affecting the adult population. However, the prevalence of low back pain in the older age population is not accurately known.Methods.A methodologic search of five computerized bibliographic databases was performed to identify citations on the prevalence of low back pain in the elderly. Data were summarized, and prevalence studies were critically appraised in detail for their quality.Results.There is wide variability in the reported prevalence of back pain. Many factors have been proposed to explain these findings including sample source, study design, definitions of back pain, and use of patient-reported data. Comorbidity among older patients also contributes to the variability in the reporting of prevalence of back pain.Conclusion.There is an under-representation of the older population in the back pain literature. The data in the current study suggest that the prevalence of low back pain in this population is not known with certainty and is not comparable with that in the younger population. The authors stress the need for future studies to improve the reporting of age information to make prevalence studies more informative and applicable.

ISSN:0362-2436    

出版商:OVID    

年代:1999

数据来源: OVID