ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignMacroscopic and microscopic investigations of the human lumbar facet joint capsule were undertaken.ObjectiveTo describe the morphologic characteristics of the fibrous capsule of the lumbar facet joints.Summary of Background DataPrevious biomechanical and neurophysiologic studies by the authors have shown that the lumbar facet joint capsule may be a source of low back pain.MethodsMacroscopic investigation was performed on the facet joint capsules dissected from five fresh adult cadavers. For microscopic studies, facet joint capsules obtained from cadaver dissection and spinal surgeries were stained by the hematoxylin and eosin method and the Elastica-Van Gieson method.ResultsThe outer layer of the fibrous capsule is a dense regular connective tissue that is composed of parallel bundles of collagenous fibers. The inner layer of the fibrous capsule consists of bundles of elastic fibers, similar to the ligamentum flavum. In the superior and middle part of the joint, the fibers run in the medial to lateral direction, crossing over the joint gap. In the inferior part of the joint, the fibers are relatively long and run in a superior-medial to inferior-lateral direction, covering the inferior articular recess. They are thicker than the layer in the superior and middle parts of the joint.ConclusionsAnatomical and histologic features of the lumbar facet joint capsule are different between its outer layer and inner layer. This complex of morphologic factors can affect the biomechanics and neurophysiology of the lumbar facet joint.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignVertebral morphology of the cervicothoracic junctional region was studied using the C6 to T4 vertebrae from 51 disarticulated skeletons (26 males and 25 females).ObjectivesOrientation of the facet joint pair relative to the plane of the superior endplate and the sagittal reference was recorded. A vertebral index was developed to compare the superior endplate surface area with the posterior vertebral body height.Summary of Background DataVertebral morphometry was recorded for comparison with the limited published data for this region.MethodsThe disc-facet angle was measured using a zygapophysial endplate protractor and the facet angle recorded from computer-aided digitizing of photographs of each segment. Vertebral dimensions were measured using Mitutoyo digital calipers.ResultsA marked change in disc-facet angle from C6 to T1 was recorded, with the incidence of right versus left asymmetry highest at the T1 level. The incidence of facet angle asymmetry greater than 10° was 24% at C6, 18% at C7, and 16% at T1. The vertebral index indicated no significant gender difference.ConclusionConsistent with other junctional regions of the spine, the cervicothoracic transition has significant morphological variations.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignSegmental mobility and intradiscal pressure were measured and the data compared in six cadaveric lumbar spine specimens before and afterin vitrosimulated single level L4-5 and double level L4-5-S1 anterior interbody fusions.ObjectiveThe experimental objective was to study the biomechanical effects of single level L4-5 and double level L4-5-S1 anterior interbody fusions on the neighboring unfused segments.Summary of Background DataThe relationship between the local rigidity created by fusion mass and accelerated degeneration reported at the neighboring unfused intervertebral discs is not clear.MethodsSix cadaveric lumbar spine specimens were biomechanically tested in flexion and extension. Segmental mobility and intradiscal pressure of the specimens were measured before and afterin vitrosimulation of single level L4-5 and double level L4-5-S1 anterior interbody fusions.ResultsThe mobility of the motion segments immediately above and below an L4-5 fusion was increased in flexion. When the L5-S1 segment was also fused, the loss of segmental motion in both flexion and extension at the L4-5 and L5-S1 were compensated for by increased motion in all levels above the fusion. In both flexion and extension, the intradiscal pressures of all unfused intervertebral discs were increased after a single level L4-5 fusion and this increase was even more marked after a double level L4-5-S1 fusion.ConclusionsThere is no evidence that the neighboring unfused segments are loaded beyond their physiological limits due to the fusion. However, the neighboring unfused segments have to work more frequently toward the extremes of their functional ranges of motion after fusion and these effects will be more marked after a double level L4-5-S1 fusion.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignIn embalmed human bodies the tension of the long dorsal sacroiliac ligament was measured during incremental loading of anatomical structures that are biomechanically relevant.ObjectivesTo assess the function of the long dorsal sacroiliac ligament.Summary of Background DataIn many patients with aspecific low back pain or peripartum pelvic pain, pain is experienced in the region in which the long dorsal sacroiliac ligament is located. It is not well known that the ligament can be easily palpated in the area directly caudal to the posterior superior iliac spine. Data on the functional and clinical importance of this ligament are lacking.MethodsA dissection study was performed on the sacral and lumbar regions. The tension of the long dorsal sacroiliac ligament (n = 12) was tested under loading. Tension was measured with a buckle transducer. Several structures, including the erector spinae muscle, the posterior layer of the thoracolumbar fascia, the sacrotuberous ligament, and the sacrum, were incrementally loaded (with forces of 0-50 newtons). The sacrum was loaded in two directions, causing nutation (ventral rotation of the sacrum relative to the iliac bones) and counternutation (the reverse).ResultsForced nutation in the sacroiliac joints diminished the tension and forced counternutation increased the tension. Tension in the long dorsal sacroiliac ligament increased during loading of the ipsilateral sacrotuberous ligament and erector spinae muscle. The tension decreased during traction to the gluteus maximus muscle. Tension also decreased during traction to the ipsilateral and contralateral posterior layer of the thoracolumbar fascia in a direction simulating contraction of the latissimus dorsi muscle.ConclusionsThe long dorsal sacroiliac ligament has close anatomical relations with the erector spinae muscle, the posterior layer of the thoracolumbar fascia, and a specific part of the sacrotuberous ligament (tuberoiliac ligament). Functionally, it is an important link between legs, spine, and arms. The ligament is tensed when the sacroiliac joints are counternutated and slackened when nutated. The reverse holds for the sacrotuberous ligament. Slackening of the long dorsal sacroiliac ligament can be counterbalanced by both the sacrotuberous ligament and the erector muscle. Pain localized within the boundaries of the long ligament could indicate among other things a spinal condition with sustained counternutation of the sacroiliac joints. In diagnosing patients with aspecific low back pain or peripartum pelvic pain, the long dorsal sacroiliac ligament should not be neglected. Even in cases of arthrodesis of the sacroiliac joints, tension in the long ligament can still be altered by different structures.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignA new magnetic resonance image analysis method is proposed which is based on the definition of the borders of the vertebral bodies adjacent to the intervertebral disc and their varying relationships. The reproducibility of this method (the socalled “centroid” method) was assessed by consecutive measurements. Its potential to depict diurnal disc height variations was studied using randomized groups of volunteers.ObjectiveTo determine if magnetic resonance imaging can reliably measure disc height variations in the lumbar spinein vivo.Summary of Background DataA review of the literature indicates that noninvasive, accurate methods to study the effect of load on intervertebral discsin vivoare needed.MethodsThe reproducibility of the centroid method was assessed in 10 healthy volunteers in 2 consecutive measurements and compared to a conventional method (mean anterior and posterior disc height). To investigate the potential for the depiction of diurnal disc height variations, 10 volunteers were randomized in a study group (1 measurement in the morning, 1 measurement in the evening) and a control group (2 consecutive measurements in the morning).ResultsThe centroid method allows the depiction of disc height variations as small as 0.85 mm with a 95% confidence (tolerance limits), whereas a conventional method needs variations of at least 1.66 mm. In the study (diurnal) group, the disc height decreased significantly (P< 0.0001) during the day (mean, -0.9 mm), while no variation (P< 0.8) was found in the control group.ConclusionsThese results indicate that the centroid method can reliably detect disc height variations in an experimental setting. The centroid method provides the potential for evaluations of the effects of various work places, work equipment, work tasks, and postures.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignThe diagnostic information achieved by a combination of ultrasonographic imaging of discs and local bony vibration of lumbar vertebrae was compared to that obtained by discographic imaging and pain provocation.ObjectivesThe purpose of this study was to find a noninvasive method for spine diagnostics to replace expensive and invasive methods such as discography.Summary of Background DataInternal anular fissures of the lumbar discs have been shown to be a source of back pain. Intradiscal changes associated with disc degeneration can be imaged by ultrasonography. The bony vibration test of spinal processes has shown to correlate well with discographic pain provocation tests in cases of internal anular ruptures. Discographic examination of the spine is the only widely accepted diagnostic method that combines pathoanatomic changes and patients' pain.MethodsPatients with back pain in this study were examined by means of ultrasonography, bony vibration stimulation, and discography. The three lowest lumbar discs were examined.ResultsIn the cases of intradiscal ultrasound findings, the vibration provocation test showed a sensitivity of 0.90 and a specificity of 0.75 compared to the discographic pain provocation test. In cases of total anular ruptures seen in ultrasound examination, the sensitivity and the specificity of the vibration pain provocation test were much lower, being 0.50 and 0.50, respectively.ConclusionThe combination of the two noninvasive methods provides a useful screening test for the evaluation of low back pain. The combination test can accurately depict painful disc degeneration with internal disc rupture and the use of discography can be limited to the cases suggesting total anular rupture in ultrasound examination.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignThis study evaluated the preconditions for exact axial rotation measurement and the possibility for other parameters to measure axial rotation and mechanical torsion.ObjectivesQuality criteria for axial rotation measurement in computed tomography scans are not established yet. Criteria should be found to improve axial rotation measurement.Summary of Background DataTo the authors' knowledge, no systematic analysis of the errors of axial rotation measurement based on computed tomography scans has been performed.MethodsAxial rotation was measured in 259 computed tomography scans of 11 cadaveric vertebrae from scoliotic specimens. The sagittal axial rotation measurement angle of Aaro and Dahlborn and a new rotation parameter were measured with a pencil and ruler. Five landmarks were digitized and consequently five axial rotation parameters were computed. The influence of insufficient visualization of bony landmarks, mechanical torsion of the vertebra itself, and oblique position of the vertebra was evaluated.ResultsAccuracy is considerably improved in central computed tomography scans (same distance to the top and bottom of the vertebral body) due to good visualization of landmarks and reduction of effects of mechanical torsion. The oblique vertebral position causes more errors. One mechanical torsion parameter with sufficient reliability is identified.ConclusionThe sagittal axial rotation measurement method of Aaro and Dahlborn is superior to other techniques of measurement. It can be improved considerably if computed tomography scans fulfill certain quality criteria.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignThis study analyzed anteroposterior, lateral, inlet, and outlet radiographic representations of different iliosacral screw orientations and evaluated anatomic features of the superior aspects of the sacral alae.ObjectivesThe purpose of this anatomical and radiologic study was to assess the value of anteroposterior, inlet, outlet, and lateral views with regard to the planning of iliosacral screw placement, to determine if screws penetrating the sacral surfaces and foramina can be detected during or after operation, and to evaluate the anatomy of the superior aspects of the sacral ala quantitatively.Summary of Background DataDirect iliosacral screw fixation has recently become popular because it provides stable fixation using reasonably small implants and is biomechanically equal or superior to other techniques of internal fixation. However, misinterpretation of the relationship of pelvic radiographs and the position of a screw may result in incorrect screw placement during surgery or misdiagnosis of postoperative neurologic complications. The morphology of the sacrum is complex. No previous data relative to the superior aspect of the sacral alae are available.MethodsFour bony pelves were used to model the different iliosacral screw orientations possible during iliosacral reconstruction. A drill bit was inserted laterally from the posterior ilium through the sacroiliac joint and into the S1 vertebra. Radiographs were taken from anteroposterior, lateral, inlet, and outlet views for evaluation of placement. Twenty-two dry sacra were obtained for anatomic evaluation of the superior aspects of the sacral alae. All symmetrical structures were measured bilaterally. Measurements included three angular and two linear parameters.ResultsThe results showed that a misdirected drill bit penetrating the anterior aspect of the ala is best appreciated by the inlet view. A misdirected drill bit penetrating the superior aspect of the ala or the S1 foramen is best represented in the outlet view. The average angle between the coronal plane of the S1 vertebra and the anterior aspect of the ala was 27.1°; between the superior aspect of the S1 vertebral body and superior edge of the ala, 36.9°; and between the superior aspect of the S1 vertebral body and posterosuperior edge of the ala, 24.5°.ConclusionsThe inlet view shows the orientation of screws relative to the coronal plane and extraosseus screws extending anterior to the ala, whereas the outlet view elucidates the placement of screws relative to the transverse plane and extraosseus screw tips extending into the sacral foramina or superior to the ala. Evaluation of preoperative pelvic computed tomography scans may be helpful in understanding the unique morphology of each individual patient and enhancing the safety of iliosacral screw placement.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID

摘要:

Study DesignRetrospective review of all patients who underwent surgical treatment of cervical spondylitic myelopathy and were monitored by somatosensory evoked potentials.ObjectivesTo identify the patients who had recognizable improvements in somatosensory evoked potential signals intraoperatively and to correlate the changes in somatosensory evoked potential signals to the postoperative clinical status of the patients and compare this group of patients with those that had stable intraoperative somatosensory evoked potential recordings.Summary of Background DataSomatosensory evoked potentials are commonly used in the operating room to monitor potential injury to the spinal cord or alterations in spinal cord function. It may be possible to use intraoperative somatosensory evoked potentials to detect improvement in spinal cord function during the decompression of neural structures, as evidenced by an increase in amplitude or a decrease in the latency of the wave form.MethodsThirty-two patients with moderate to severe cervical spondylitic myelopathy requiring multilevel anterior decompression and fusion were monitored intraoperatively with somatosensory evoked potentials. The median and posterior tibial nerves were stimulated at the wrist and ankle, respectively. Somatosensory evoked potential recordings were obtained from cervical and scalp electrodes by the Nicolet Pathfinder electrodiagnostic system, preoperatively, intraoperatively, and postoperatively.ResultsEleven of thirty-two patients demonstrated intraoperative improvement of somatosensory evoked potential signals after decompression. All patients had rapid recovery of motor strength, bladder control, and ambulatory capacity within days of surgery. The remaining twenty-one patients had stable somatosensory evoked potential recordings. Five had rapid resolution of their symptoms, 15 improved over the course of 6 to 8 weeks, and 1 did not improve. The motor recovery of this group at 8 weeks was equal to the group of patients that showed intraoperative improvements of evoked potential signals.Conclusions1) Multilevel anterior cervical decompression and fusion produced a significant improvement in the motor function of patients with cervical spondylitic myelopathy. 2) Patients with intraoperative increase in amplitude or shortening of latency had a more rapid clinical improvement than patients with stable recordings. 3) Long-term reassessment did not show any difference between patients with intraoperative somatosensory evoked potential improvement and those with stable somatosensory evoked potential recordings. Therefore, somatosensory evoked potential improvements cannot be used to determine prognosis at the present time. 4) A greater number of patients should be studied using more objective methods for quantifying gait patterns and motor function.

ISSN:0362-2436    

出版商:OVID    

年代:1996

数据来源: OVID