摘要:

Study Design.Vertebral columns from 11 normal human fetuses (10–24 weeks of gestation) derived from spontaneous abortions were examined as part of the legal autopsy procedure including spinal cord analysis.Objectives.To study the localization of the dorsal root ganglion in the normal fetal spine and to relate the dorsal root ganglion location to the ossification of the vertebral bodies and vertebral arches.Summary of Background Data.The normal and pathologic ossification pattern of the fetal human spine has been studied. There has been no study addressing the localization of the dorsal root ganglion in normal and pathologic axial development.Methods.The dorsal root ganglion were studied by using histology (horizontal sections) and morphometric measurement.Results.The study showed: 1) The dorsal root ganglion appeared before ossification of the spine; 2) The dorsal root ganglion had an oval shape in all cases; 3) The longitudinal axis of dorsal root ganglion was directed anterolaterally in the cervical and lumbosacral segments and mainly laterally in the thoracic segment; 4) During development, the dorsal root ganglion changed position according to the body axis; and 5) The para-axial ossification protected the dorsal root ganglion differently in the different axial segments.Conclusions.The dorsal root ganglion appeared before ossification. The distance from the dorsal root ganglion to the body axis increased during development. In the different segments of the spine, different orientations and different locations of the dorsal root ganglion were observed in relation to osseous spine components. The results can be used as reference data for future studies on the dorsal root ganglion in pathologic spines.

ISSN:0362-2436    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Study Design.A repeated-measuresin vitroflexibility test was performed.Objectives.To determine the biomechanical functions of tissues resected during anterior cervical decompression of various extents.Summary of Background Data.The biomechanical consequences of discectomy have been studiedin vitro,and uncovertebral joint removal has been modeled numerically. No studies have assessed the relative biomechanical contributions of different anterior column structures.Methods.In seven human cadaver C4–T1 specimens, 20 motion segments were studied. After each destructive step, including discectomy, unilateral uncinate process removal, bilateral uncinate process removal, and posterior longitudinal ligament transection, torques were applied to four-level specimens while the angular motion was measured at each level.Results.Angular range of motion and neutral zone increased by variable but statistically significant amounts after each progressive resection, most notably in flexion and extension. Each resection step caused progressively larger shifts (up to 23 mm) in the location of the axis of rotation. Uncovertebral joint resection caused the most significant changes in the observed angular coupling.Conclusions.Anterior cervical decompression significantly increases the instability and alters the kinematics of cervical motion segments. Each structure resected contributes to normal stability and kinematics, so as many structures as possible should be left intact during anterior decompression without fusion. Because flexion and extension were the modes of motion that increased most significantly after decompression, the primary function of a grafting technique or fixation device should be to limit these motions.

ISSN:0362-2436    

出版商:OVID    

年代:2001

数据来源: OVID

ISSN:0362-2436    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Study Design.A biomechanical study was designed to assess relative rigidity provided by anterior, posterior, or combined cervical fixation using cadaveric cervical spine models for flexion–distraction injury and burst fracture.Objectives.To compare the construct stability provided by anterior plating with locked fixation screws, posterior plating with lateral mass screws, and combined anterior-posterior fixation in clinically simulated 3-column injury or corpectomy models.Summary of Background Data.Anterior plating with locked fixation screws is the most recent design and is found to provide better stability than the conventional unlocked anterior plating. However, there are few data on the direct comparison of biomechanical stability provided by anterior plating with locked fixation screwsversusposterior plating with lateral mass screws. Biomechanical advantages of using combined anterior-posterior fixation compared with that of using either anterior or posterior fixation alone also have not been well investigated yet.Methods.Biomechanical flexibility tests were performed using cervical spines (C2–T1) obtained from 10 fresh human cadavers. In group I (5 specimens), one-level, 3-column injury was created at C4–C5 by removing the ligamentum flavum and bilateral facet capsules, the posterior longitudinal ligament, and the posterior half of the intervertebral disc. In group II (5 specimens), complete corpectomy of C5 was performed to simulate burst injury. In each specimen, the intact spine underwent flexibility tests, and the following constructs were tested: (1) posterior lateral mass screw fixation (Axis plate) after injury; (2) polymethylmethacrylate anterior fusion block plus posterior fixation; (3) polymethylmethacrylate block plus anterior (Orion plate) and posterior plate fixation; and (4) polymethylmethacrylate block plus anterior fixation. Rotational angles of the C4–C5 (or C4–C6) segment were measured and normalized by the corresponding angles of the intact specimen to study the overall stabilizing effects.Results.Posterior plating with an interbody graft showed effective stabilization of the unstable cervical segments in all loading modes in all cases. There was no significant stability improvement by the use of combined fixation compared with the posterior fixation with interbody grafting, although combined anterior-posterior fixation tended to provide greater stability than both anterior and posterior fixation alone. Anterior fixation alone was found to fail in stabilizing the cervical spine, particularly in the flexion–distraction injury model in which nocontribution of posterior ligaments is available. Anterior plating fixation provided much greater fixation in the corpectomy model than in the flexion–distraction injury model. This finding suggests that preservation of the posterior ligaments may be an important factor in anterior plating fixation.Conclusions.This study showed that the posterior plating with interbody grafting is biomechanically superior to anterior plating with locked fixation screws for stabilizing the one-level flexion–distraction injury or burst injury. More rigid postoperative external orthoses should be considered if the anterior plating is used alone for the treatment of unstable cervical injuries. It was also found that combined anterior and posterior fixation may not improve the stability significantly as compared with posterior grafting with lateral mass screws and interbody grafting.

ISSN:0362-2436    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Study Design.Compressive and shear trabecular strains were evaluated using six cadaveric thoracic spines that included anterior osteophytes. The treatments were divided into three groups: 1) osteophytes intact and the specimen in the neutral position, 2) osteophytes removed and the specimen in the neutral position, and 3) osteophytes removed and the specimen with 5° of additional flexion.Objectives.To investigate the influence of osteophytes and flexural position on vertebral trabecular strain during axial compression.Summary of Background Data.In the thoracic spine, the incidence of anterior wedge fractures increases with the severity of kyphosis. It is unclear whether the role of anterior osteophytes in the thoracic spine is to restrict progressive kyphosis, conduct axial load anteriorly, or both.Methods.Thoracic motion segments, T10–T12, were axially loaded in compression, and the minimum principal and maximum shear strains were measured using texture correlation.Results.No dramatic changes were found in the spatial distribution of the strains following removal of the anterior osteophytes. Conversely, after removal of the osteophytes and orienting the specimen in 5° of additional flexion, the strain distribution shifted anteriorly and the magnitude increased.Conclusions.This study demonstrated that osteophytes seem to restrict progressive kyphosis rather than conduct axial load anteriorly.

ISSN:0362-2436    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Study Design.Forty-one cases of aneurysmal bone cyst of the mobile spine were retrospectively reviewed.Objectives.To evaluate the role of surgical and nonsurgical treatment of aneurysmal bone cyst of the spine.Summary of Background Data.Ten to 30% of aneurysmal bone cysts arise from the mobile spine, frequently occurring in pediatric patients. The course of the disease depends on the aggressiveness of the tumor, as well as the treatment. Intralesional surgery seems to be an effective treatment, as well as radiotherapy and embolization.Methods.All charts, radiographs, and images were reviewed. The composite information provided by this review allowed for oncologic and surgical staging of these cases. Thirty-two patients underwent curettage (14 of them followed by radiotherapy), four were submitted to selective arterial embolization, three received radiotherapy alone, and two underwenten blocexcision.Results.All patients were found alive and disease free at final follow-up evaluation. Two recurrences followed one incomplete curettage and one embolization. The combination of curettage and radiotherapy, although effective, showed the greatest incidence of late axial deformity. Selective arterial embolization was curative in three of four cases and did not affect the possibility of surgery in case of local recurrence.Conclusions.If confirmed on larger series, selective arterial embolization seems to be the first treatment option for spine aneurysmal bone cyst, because of the low cost-to-benefit ratio. Diagnosis must be certain, based on pathognomonic radiographic pattern or on histologic study.— In case of neurologic involvement, pathologic fracture, technical impossibility of performing embolization, or local recurrence after at least two embolization procedures, complete intralesional excision would be the therapy of choice.

ISSN:0362-2436    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Study Design.Retrospective cohort.Objectives.1) Evaluate the utility of the Québec Classification of Whiplash-Associated Disorders as an initial assessment tool; 2) assess its ability to predict persistence of symptoms at 6, 12, 18, and 24 months postcollision; 3) examine one potential modification to the Classification.Summary of Background Data.In 1995, a task force from Québec, Canada, developed the Québec Classification of Whiplash-Associated Disorders to assist health care workers in making therapeutic decisions. The Classification was applied to an inception cohort of patients presenting for emergency medical care following their involvement in a rear-end motor vehicle collision.Methods.All patients (n = 446) presenting to the only two emergency departments serving Kingston, Ontario, between October 1, 1995 and March 31, 1998 were considered for inclusion in the study. Eligible patients (n = 380) were categorized according to the Classification based on signs and symptoms documented in their emergency medical chart. Attempts were made to interview all patients shortly following and again 6 months after their collision. Patients were contacted at 12, 18, and 24 months postinjury only if sufficient time had elapsed between recruitment into and cessation of the study. Data were gathered regarding symptoms, treatments received, effects on usual activities, crash circumstances, and personal factors. Associations between initial Classification grade and the frequency/intensity of follow-up symptoms were quantifiedviamultivariable analyses.Results.The Classification was prognostic in that risk for Whiplash-Associated Disorders at 6, 12, 18, and 24 months increased with increasing grade. Analyses supported modification of the Classification to distinguish between Grade II cases of Whiplash-Associated Disorders with normal or limited range of motion. The greatest risk for long-term symptoms was seen among the group of patients with both point tenderness and limited range of motion.Conclusion.The analyses of this study support the use of the Québec Classification of Whiplash-Associated Disorders as a prognostic tool for emergency department settings, and the authors propose a modification of the Classification using a subdivision of the Grade II category.

ISSN:0362-2436    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Study Design.Retrospective analysis of outcome in terms of incidence of surgery for adolescent idiopathic scoliosis during a period when bracing was not practiced.Objectives.To determine whether centers with an active bracing policy have lower numbers undergoing surgery for adolescent idiopathic scoliosis than a center where nonintervention is the practice.Background Data.Two major recent publications have claimed that bracing significantly improves the outcome in adolescent idiopathic scoliosis. However, one had no control subjects and the other did not examine the final status of the subjects under review. While statistically significant differences in progression have been observed, what will convince patients to submit to an onerous treatment is the conviction that it will make a substantial difference, such as the avoidance of surgery.Methods.Since 1991, bracing has not been recommended for children with adolescent idiopathic scoliosis at this center. The scoliosis database was searched for patients with adolescent idiopathic scoliosis who were at least 15 years of age at last review and who had adequate documentation of curve parameters. The incidence of surgery was compared with that of published data from other centers.Results.A total of 153 children, 11 boys and 142 girls, fitted the criteria. Forty-three of these (28.1%) have undergone surgery. This was not statistically different from the surgery rate reported from an active bracing center.Conclusions.If bracing does not reduce the proportion of children with adolescent idiopathic scoliosis who require surgery for cosmetic improvement of their deformity, it cannot be said to provide a meaningful advantage to the patient or the community. Recent studies notwithstanding, the question of the efficacy of orthoses in idiopathic scoliosis remains unresolved.

ISSN:0362-2436    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Study Design.A transversal study involving group comparison was performed.Objective.To investigate whether children who are visually impaired have a higher rate of spinal deformity.Summary of Background Data.Evidence has accumulated pointing to an association between idiopathic scoliosis and postural control in which vision is involved. An association between scoliosis and ocular troubles is present in many diseases, but no study on a large blind population has yet been undertaken.Methods.Data was obtained from an official school screening campaign involving two consecutive classes in a regional school for the visually handicapped and from two consecutive classes in three public vocational schools. This study included 75 children who were visually handicapped (mean age, 11 years and 7 months) and 728 healthy control participants (mean age, 10 years 2 months). Trunk deformity was assessed by Moire topography and measurement of any trunk hump by the forward bending test. The children with visual impairment who had evidence of trunk deformity underwent radiographs of the spine a few months after the back surface assessment, then again 12 to 24 months later.Results.Occurrences of trunk deformity were significantly different in the two groups (P< 0.0001), with five times more back surface abnormalities in the blind population. Of the 26 children with both visual impairment and trunk deformity, 18 had a structural scoliosis on radiographs, with an average Cobb Meyer angle of 14.1° (range, 10–28°), but there was evidence of an evolving condition in only three cases.Conclusions.These findings are compatible with a postural etiology of scoliosis in the visually impaired population.

ISSN:0362-2436    

出版商:OVID    

年代:2001

数据来源: OVID

摘要:

Study Design.Repeated measures for intratester reliability were performed.Objectives.To investigate the intratester reliability of a new measurement technique that evaluates lumbar range of motion in three planes using a pelvic restraint device, and to examine the reliability of lumbar lordosis measurement by inclinometer technique. Preliminary normative data on lumbar range of motion and lumbar lordosis were collected for comparison with the findings of previous studies.Summary of Background Data.Various noninvasive measurement methods have been developed for recording lumbar range of motion. However, pelvic movement was not effectively restricted during the use of these measurement techniques. The use of the pelvic restraint device to measure lumbar range of motion has not been investigated previously. Very few studies have investigated the reliability of quantifying lumbar lordosis by the inclinometer technique.Methods.Normative values were measured in 35 healthy men, and 12 of these subjects were included for the reliability study. Pelvic motion was limited by the pelvic restraint device during lumbar range of motion measurement in standing. An inclinometer was used for evaluation of lumbar flexion, extension, lateral flexion, and lumbar lordosis, whereas a lumbar rotameter was used to measure axial rotation.Results.Good intratester reliability was shown in the lumbar range of motion and lordosis measurement. Most of the intraclass correlation coefficient and Pearson’s r values (accompanied with nonsignificant pairedttests) were greater than 0.9, and most of the intrasubject coefficients of variation were less than 10%. The values of lumbar range of motion in three planes and lumbar lordosis found in the current study were comparable with those from most of the previous studies on these measurements in the normal population.Conclusions.Inclinometer and lumbar rotameter measurements with the use of a pelvic restraint device are reliable for measuring lumbar spine range of motion. Use of the inclinometer technique to record lumbar lordosis also is a reliable measure.

ISSN:0362-2436    

出版商:OVID    

年代:2001

数据来源: OVID