摘要:

Study Design.A retrospective follow-up study of spine geometry after posterior instrumentation and fusion for adolescent idiopathic scoliosis (AIS).Objectives.To evaluate 1) if Cobb angle progression is a reliable indicator of the crankshaft phenomenon; 2) if significant growth of the spine can occur after surgery without the development of a crankshaft phenomenon?Summary of Background Data.Anterior fusion of the spine is often recommended for skeletally immature scoliotic patients to avoid the risk of a crankshaft phenomenon, a long-term loss of curve correction caused by residual growth of the spine combined with the constraints of a posterior fusion. The crankshaft phenomenon is usually assessed indirectly by documenting progression of the Cobb angle on frontal radiographs. Thus far, no study has directly measured the three-dimensional growth of the spine after surgery in AIS.Methods.Cobb angle, spine length and spine height were obtained from three-dimensional radiographic reconstructions of the spine in 48 adolescent scoliotic patients undergoing posterior instrumentation and fusion. Measurements were done before surgery, after surgery and at skeletal maturity. A significant growth of the spine was defined as a ≥10 mm increase in spine length, while a significant curve progression was defined as a ≥10° increase in Cobb angle at skeletal maturity.Results.In the majority of patients (56%), there was no significant change in spinal length or in Cobb angle measurements at an average 2.4 years post surgery. A crankshaft phenomenon was detected in 6 patients (12%) for which significant increases both in spinal length and Cobb angle measurement were found. Significant curve progression without any change in spine length was noted in 9 patients (19%) while an increase in spine length with no evidence of curve progression was present in 6 patients at last follow-up.Conclusion.Spinal growth as indicated by an increase in spinal length can be measured in a significant proportion of adolescents with idiopathic scoliosis after posterior instrumentation and fusion. Some of these study participants will develop a crankshaft phenomenon but Cobb angle progression is not a reliable indicator of this complication, since it may occur without any detectable growth of the spine.

ISSN:0362-2436    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Study Design.An intramuscular electromyographic study was performed on trunk rotations during sitting and standing.Objective.The aim was to provide new information on activation levels for deep trunk muscles in various unresisted and resisted trunk rotations.Summary and Background Data.Frequent daily trunk twisting and decreased maximal strength during trunk rotation have been associated with low back pain or sciatic pain. However, the involvement of deep trunk muscles during different trunk rotations is relatively unknown.Methods.Ten healthy subjects participated. Fine-wire electrodes were inserted, under ultrasound guidance, into psoas, quadratus lumborum, the superficial medial lumbar erector spinae (ES-s, multifidus) and its deep lateral portion (ES-d, iliocostalis), iliacus, rectus abdominis, obliquus externus, and obliquus internus.Results.The highest involvement for all muscles was observed on the ipsilateral side, in maximal trunk twists with shoulder resistance, except obliquus externus, which showed a dominant contralateral side, and rectus abdominis, which was little activated in all rotations. In contrast, maximal trunk twist without shoulder resistance,i.e., freely performed, resulted generally in lower levels for all muscles involved and in a shift of side dominance for the lumbar muscles quadratus lumborum, psoas, and ES-s.Conclusions.During trunk rotations the activity patterns for various trunk muscles could drastically change, and even be the opposite, between the two body sides, within the same type of task, depending on several factors such as initial position, effort level, sitting or standing, and external shoulder resistance.

ISSN:0362-2436    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Background.In an attempt to increase fusion while decreasing the neurologic risk associated with complete reduction of high-grade spondylolisthesis, the authors have used a technique of partial lumbosacral kyphosis reduction, posterior decompression, and pedicle screw transfixation of the lumbosacral junction.Objective.To determine if this technique is effective in treatment of high-grade spondylolisthesis.Study Design.A retrospective review of six patients with high-grade spondylolisthesis treated by this technique was performed. There were four female patients (ages 16 years [n=2], 23 years [n=1], and 29 years [n=1]) and two male patients (both 13 years of age) with spondylolisthesis ranging from Grade IV to Grade V. All patients presented with pain and radiculopathy. After surgery the patients were evaluated for resolution of symptoms, sagittal alignment, fusion, and satisfaction. The radiographic measurements included the slip angle, the percentage slip, and the sacral inclination. An SRS outcome score was also obtained on all six patients to evaluate postoperative outcome, in terms of pain control, self-image perception, and return to function.Results.The average length of follow-up was 42.6 months (range 24–60 months). All patients evidenced solid fusion by the 6-month follow-up (based on oblique radiographs showing lateral bridging bone masses). The slip angle was improved from 62° to 28° (P< 0.5), whereas there was no significant improvement in the percentage slip or the sacral inclination (89–80% and 28–37°, respectively). No progression of the slip angle or percentage slip was noted on the follow-up radiographs. Complications included two intraoperative dural tears that were identified and repaired. There were no neurologic complications. The SRS outcome instrument demonstrated good postoperative pain control, function, self-image, and satisfaction in all patients.Conclusion.In high-grade spondylolisthesis, this posterior approach is safe and effective in obtaining a solid arthrodesis, restoring sagittal balance, and improving function. These results reinforce the impression that it is the partial reduction of the slip angle, not the percentage slip, in high-grade spondylolisthesis that is important in obtaining optimal results.

ISSN:0362-2436    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Study Design.An anatomic study of the associations between the fifth lumbar spinal nerve (L5 spinal nerve) and a lumbosacral tunnel, consisting of the fifth lumbar vertebral body (L5 vertebral body), the lumbosacral ligament, and sacral ala, and clinical case reports of four patients with lumbar radiculopathy secondary to entrapment of the L5 spinal nerve in the lumbosacral tunnel.Objectives.To delineate the anatomic, clinical, and radiologic features and surgical outcome of patients with entrapment of the L5 spinal nerve in the lumbosacral tunnel.Summary of Background Data.Although several cadaveric studies on a lumbosacral tunnel as a possible cause of L5 radiculopathy have been reported, few studies had focused on osteophytes of the L5–S1 vertebral bodies as the major component of this compressive lesion, and clinical reports on patients with this disease have been rare.Methods.Lumbosacral spines from 29 geriatric cadavers were examined with special attention to the associations between osteophytes of the L5–S1 vertebral bodies and the L5 spinal nerve. Four patients with a diagnosis of the entrapment of the L5 spinal nerve by osteophytes at the lumbosacral tunnel were treated surgically, and their clinical manifestations and surgical results were reviewed retrospectively.Results.The anatomic study demonstrated osteophytes of the L5–S1 vertebral bodies in seven of the 29 cadavers. Entrapment of the L5 spinal nerve in the lumbosacral tunnel was observed in six of the seven cadavers with L5–S1 osteophytes but in only one of the 22 cadavers without such osteophytes (P< 0.05, &khgr;2test). All four patients had neurologic deficits in the L5 nerve root distribution. MRI and myelography showed no abnormal findings in the spinal canal, but CAT scans demonstrated prominent osteophytes on the lateral margins of L5–S1 vertebral bodies in all four. Selective L5 nerve block completely relieved all patients of pain but only temporarily. Three patients were treatedviaa posterior approach by resecting the sacral ala along the L5 spinal nerve, and the other patient was treated by laparoscopic anterior resection of the osteophytes. Pain relief was obtained in the four patients immediately after surgery, but one patient experienced recurrence of pain 1 year after the first surgery and was successfully treated by additional posterior decompression and fusion.Conclusions.Extraforaminal entrapment of L5 spinalnerve in the lumbosacral tunnel can cause L5 radiculopathy, and osteophytes of L5–S1 vertebral bodies are a major cause of the entrapment.

ISSN:0362-2436    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Study Design.A case report is presented involving a subdural hematoma after cervical epidural steroid injection.Objective.To demonstrate a previously unreported complication of cervical epidural steroid injection.Summary of Background Data.Cervical epidural steroid injection is a common procedure performed in the care of patients with spine-related complaints. Reports of complications are rare, and most of these are fairly benign. To the authors’ knowledge, subdural hematoma has never been described as a complication of a cervical epidural steroid injection.Methods.A patient underwent an uncomplicated cervical epidural steroid injection by an experienced anesthesiologist. She developed acute onset of axial pain followed by progressive quadriparesis within a matter of 8 hours. She was transferred from a local emergency room after a CT scan suggested posterior cord displacement consistent with an anterior spinal hematoma from C3 to C5. She was taken to the operating room for urgent decompression. Exploration revealed an anterior subdural hematoma that was evacuated followed by dural closure with a patch.Results.After surgery the patient was initially quadriplegic but rapidly gained full function in the left upper and lower extremities. She was making steady progress with motor recovery on the right side when she developed acute meningitis about 8 days after surgery, and then she subsequently went into cardiopulmonary arrest. She was successfully resuscitated but remained critically ill with no evidence of encouraging neurologic function. Six days later she had a second cardiac arrest and could not be resuscitated.Conclusions.It is important to acknowledge that spinal hematomas can occur after cervical epidural steroid injection, as prompt recognition and treatment could improve the prognosis for recovery. The sequelae of a cervical subdural hematoma after epidural steroid injection remain potentially devastating.

ISSN:0362-2436    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Study Design.Cluster randomized controlled trial.Objective.To evaluate the effectiveness of two strategies to improve the use of active sick leave (ASL) for patients with low back pain.Summary of Background Data.ASL is a public sickness benefit scheme offered to promote early return to modified work for temporarily disabled workers. It was poorly used, and the authors designed two community interventions to strengthen the implementation of ASL based on the results of a study of barriers to use among back pain patients, employers, general practitioners (GPs), and local National Insurance Administration staff.Methods.Sixty-five municipalities in three counties in Norway, randomly assigned to a passive intervention, a proactive intervention, or a control group. The interventions were targeted at patients on sick leave for low back pain for more than 16 days (n = 6176), their GPs, employers, and local insurance officers. The passive intervention included reminders about ASL on the sick leave form that GPs must complete, a standard agreement to facilitate ASL, targeted information, and a desktop summary for GPs of clinical practice guidelines for low back pain, emphasizing the importance of advice to stay active. The proactive intervention included these elements plus a resource person to facilitate the use of ASL and a continuing education workshop for GPs. The main outcome measure reported here is the proportion of eligible patients that used ASL.Results.ASL was used significantly more in the proactive intervention municipalities (17.7%) compared with the passive intervention and control municipalities (11.5%,P= 0.018).Conclusions.A passive intervention that addressed identified barriers to the use of ASL did not increase its use. Although modest, a proactive intervention did increase its use. The main impact of the intervention was through direct contact and motivating telephone calls to patients. To the extent that GPs’ practice was changed, it was either patient mediated or by patients bypassing their GP.

ISSN:0362-2436    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Study Design.The sheep anterior lumbar spinal fusion model was used to study the efficacy of recombinant human bone morphogenetic protein-2 (rhBMP-2)–collagen composite in comparison with autograft to enhance spinal interbody fusion. Comparisons were drawn from temporal radiographic and end-point biomechanical and histologic data.Objective.To analyze histologically the ability of rhBMP-2 to achieve complete arthrodesis between vertebral bodies.Summary of Background Data.Studies using rhBMP for enhancement of anterior interbody fusion have used numerous endpoints. However, systematic histologic evaluation of the fusion has not been conducted.Methods.Twelve sheep underwent single-level anterior lumbar interbody fusion performed with a cylindrical fenestrated titanium interbody fusion device (INTER FIX, Medtronic Sofamor Danek, Inc., Memphis, TN). The device was filled either with rhBMP-2–collagen (n = 6) or autogenous iliac crest bone graft (n = 6). Radiologic evaluation was carried out at 2-month intervals, and all sheep were killed 6 months after surgery. Nondestructive biomechanical testing for stiffness to flexion, extension, and lateral bending moments, un-decalcified histology, and qualitative and quantitative histologic evaluation were performed.Results.Radiographs revealed a bony bridge anterior to the cage in five of six rhBMP-2-treated animals, whereas it was present only in one of five in the autogenous bone graft group. Segments treated with rhBMP-2 were 20% stiffer in flexion than autograft-treated segments at 6 months. Six of six in the rhBMP-2 group and two of six in the autograft group showed complete fusion. There was a significantly higher rate of bony continuity observed at the fenestrations of the rhBMP-2 group. Three times more number of cage fenestrations in the rhBMP-2 group demonstrated “all-bone” when compared with the autograft group (P< 0.001). Further, the scar tissue in and around the autograft-treated cages was 16-fold more (P< 0.01) than that seen for rhBMP-2-treated cages.Conclusions.The study demonstrates that rhBMP-2 can lead to earlier radiologic fusion and a more consistent increased stiffness of the segments when compared with autograft in sheep anterior lumbar interbody fusion. Furthermore, a three times higher histologic fusion rate is attainable with significantly reduced fibrous tissue around the implant when rhBMP-2 is used.

ISSN:0362-2436    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Study Design.Lumbar intervertebral discs in rabbit were cultured in the presence of chondroitinase ABC. The matrix metalloproteinases (MMPs) and inflammatory mediators produced in culture media were then analyzed.Objectives.To investigate the effect of chondroitinase ABC on MMPs and inflammatory mediators produced by intervertebral disc of rabbitin vitro.Summary of Background Data.The chemonucleolytic effect of chondroitinase ABC is caused by the decrease in the chondroitin sulfate, hyaluronan, and protein content of the nucleus pulposus in rabbit. The reason for the decreases in protein content remains unclear.Methods.Anulus fibrosus and nucleus pulposus were cultured for 72 hours with or without chondroitinase ABC stimulated or not stimulated by interleukin-1 after preculture for 4 days. Subsequently, the MMPs (gelatinases MMP-2, MMP-9, and collagenase) and inflammatory mediators (prostaglandin E2and nitric oxide) produced in the culture media were analyzed.Results.In the anulus fibrosus chondroitinase ABC and interleukin-1 synergistically increased the collagenase activity, which was at a significantly higher level than the increment solely due to interleukin-1. In contrast, chondroitinase ABC counteracted the increase in nitric oxide production by interleukin-1. In the nucleus pulposus the collagenase and nitric oxide productions were not particularly affected by chondroitinase ABC and/or interleukin-1. In zymographic analysis MMP-2 was detected, but MMP-9 was only slightly detected in both tissues. There were no significant differences in both tissues for MMP-2 and prostaglandin E2following incubation with or without chondroitinase ABC, whether stimulated by interleukin-1 or not.Conclusions.The collagenase activity in the anulus fibrosus was increased by chondroitinase ABC with interleukin-1. This finding may support the hypothesis that some proteolytic activities are involved in the chemonucleolytic process by chondroitinase ABC treatment.

ISSN:0362-2436    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Study Design.An experimental physiologic and histologic study of dexamethasone effects on peripheral nerves.Objective.To characterize the effect of topically applied 0.4% dexamethasone on acute changes in nerve blood flow and subsequent histologic changes in rat sciatic nerve fibers.Summary of Background Data.Dexamethasone is an anti-inflammatory glucocorticoid used clinically to reduce the neural consequences of inflammation. Several reports of accidental injury to nerves after steroid injections have raised questions about the mechanisms involved in dexamethasone-induced neurotoxic injury.Methods.Nerve blood flow studies using a laser Doppler flowmeter were conducted in animals with stable temperature and arterial pressure. Dexamethasone 0.4%, 0.1 mL was applied topically to rat sciatic nerve in the following protocol groups: 1) nerve blood flow recording every 5 minutes for 30 minutes, and 2) initial nerve blood flow recording and repeat recording at 4 hours. Three additional animals had 30-minute nerve blood flow recordings in which normal saline was substituted for dexamethasone; these animals were used for control and to assure that the experimental preparation was viable throughout the observational period. Additional groups of two animals each received dexamethasone but were used only for neuropathologic observation at 2, 4, and 6 days after treatment. Neuropathologic studies were conducted on glutaraldehyde-fixed, plastic-embedded tissue.Results.Application of saline to the exposed sciatic nerves did not significantly change nerve blood flow from baseline values. Nerve blood flow values remained constant throughout the observational period. Dexamethasone, however, significantly reduced nerve blood flow in both the 30-minute and 4-hour groups. Some animals showed an initial transient increase in blood flow before nerve blood flow began to steadily decline to the final values reported. Neuropathologic changes were minimal and consisted only of edema and occasional subperineurial activation of Schwann cells. No demyelination or degeneration was seen.Conclusion.Dexamethasone causes statistically significant reductions in normal nerve blood flow at 30 minutes and 4 hours after topical application; however, the reduction is on average below the threshold for causing ischemic changes in the structure of peripheral nerve fibers.

ISSN:0362-2436    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Study Design.An experimental investigation of intervertebral foramen and spinal canal neural space integrity was performed throughout physiologic range of motion of the lower cervical spine in intact human cadaver specimens.Objective.To investigate cervical positions that might place the neural tissues of the spine in heightened risk of injury. To meet this objective the following hypotheses were tested: 1) spinal canal integrity varies with specific normal range of motion positions of the lower cervical spine, and 2) intervertebral foramen integrity is dependent on and unique for different physiologic positions of the lower cervical spine.Summary of Background Data.Cervical spine injuries are frequently associated with compressive damage to neurologic tissues and consequently poor clinical outcomes. Neurologic injury typically occurs from disc, ligamentous, or bony occlusion of the spinal canal and intervertebral foraminal spaces dynamically during an injury event or with abnormal alignment and position after the injury event. Prior studies have shown pressure and geometric changes in cervical spine neural spaces in certain cervical spine positions. However, to the authors’ knowledge, this is the first research effort aimed at elucidating the integrity of the cervical spine neural spaces throughout the normal physiologic range of motion.Methods.The authors instrumented 17 fresh-frozen unembalmed cadaveric human cervical spines (C3–C7) with specially designed intervertebral foramen occlusion transducers and a spinal canal occlusion transducer. The specimens were loaded with pure bending moments to produce simulated physiologic motions of the lower cervical spine. The resulting occlusion profiles for the intervertebral foramen and spinal canal were recorded along with the 6-degree of freedom position of the cervical spine. Because these occlusion measurements describe the ability of the spine to preserve the space for the neural structures, the authors define this neuroprotective role of the vertebral column as neural space integrity.Results.The range of motion developed experimentally in this study compared well with published reports of normal cervical motion. Thus, subsequent changes in neural space integrity may be regarded as resulting from normal human cervical spine motion. No significant change in the spinal canal space was detected for any physiologic motion; however, intervertebral foramen integrity was significantly altered in extension, ipsilateral bending, combined ipsilateral bending and extension, and combined contralateral bending with extension when compared with intact upright neutral position.Conclusions.This study defines the range of neural space integrity associated with simulated physiologic motion of the lower cervical spine in an experimental setting. This information may be useful in comparing neural space changes in pathologic conditions and may enhance refinement of neurologic injury prevention strategies.

ISSN:0362-2436    

出版商:OVID    

年代:2002

数据来源: OVID