The results of anterior fusion and Cotrel-Dubousset-Hopf instrumentation in idiopathic scoliosis.
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Anterior instrumentation for the correction of scoliotic curves has recently been gaining in popularity. The problems of high mortality and morbidity that were associated with the employment of anterior instrumentation in the first years it was used have now been overcome. Efforts are now being concentrated on increasing the correction rates in the frontal plane and decreasing the kyphotic effect in the sagittal plane. The anterior Cotrel-Dubousset-Hopf (CDH) system is a recently developed instrumentation that has been claimed to decrease the kyphotic effect through the use of double rods. This study aimed to investigate the impact of the anterior CDH system on idiopathic scoliotic curves in frontal and sagittal planes. To this end, 26 idiopathic scoliosis patients treated with the CDH system were followed for a mean period of 32.8 +/- 5.3 months. In the frontal plane, Cobb angles of major and secondary curves were measured, and postoperative and final correction rates determined. In the sagittal plane, sagittal contours of both the instrumented region and the thoracic and lumbar regions were measured, and their preoperative, postoperative and final control values were determined. In addition to clinical examination, lateral trunk shift (LT), shift of head (SH) and shift of stable vertebra (SS) were measured in vertebral units (VU), on the preoperative and postoperative radiographs in order to evaluate the effect of the system on trunk balance. It was established that in patients with single flexible thoracolumbar and lumbar curves and those with rigid thoracic curves, the correction rates obtained in the frontal plane were respectively 79.4 +/- 14.8%, 68.0 +/- 9.4% and 61.5 +/- 8.0%, with statistical significance. Their final corrections at the last control were 76.3 +/- 17.4%, 56.9 +/- 9.1% and 52.3 +/- 8.3%, respectively. Although the corrections in the lumbar rigid curves were relatively low, they were still statistically significant. Taking all the patients together, the mean preoperative Cobb angle of the major curves of 67.2 degrees +/- 20.2 degrees improved to a mean of 28.6 degrees +/- 21.0 degrees, which was a statistically significant difference (P < 0.05), giving a mean correction rate of 61.2 +/- 20.3%. The mean correction loss of major curves in the frontal plane in all patients was 6.0 degrees +/- 3.8 degrees and the mean final correction rate was 52.6 +/- 23.2%. In the sagittal plane, there was a favorable kyphotic effect on the thoracic region of patients with hypokyphosis and lordosis pattern, whilst in patients with kyphotic pattern, this effect was minimal. In patients with a single flexible lumbar curve, kyphotic effect was not observed except in two patients. In these two patients, it was thought that excessive compression force may have been used. As to the pa tients with rigid lumbar curve. there was a slight decrease in lumbar lordosis. No postoperative complaints were made about imbalance. and the mean overall correction in LT values was 60.1 +/- 21.7%. While preoperatively, the SH and SS values of all patients were over 0.5 VU, postoperatively, 12 patients (46.2%) were completely balanced (SH = 0 VU, SS = 0 VU) and 8 patients (30.8%) were balanced (0 VU < SH and SS < 0.5 VU). The remaining six patients, whose balance values were corrected with statistical significance but were still over 0.5 VU, were found to be the ones with rigid lumbar curves. Implant failure and systemic complications were not noted in the follow-up period. In view of these findings, it was determined that CDH instrumentation achieves significant correction rates in the frontal and sagittal planes, particularly in single flexible lumbar, thoracolumbar and thoracic rigid curves. It was found that the kyphotic effect was minimized with a double rod system. Significant clinical and radiological corrections were achieved in balance values, without any imbalance and decompensation problems. (+info)
Influence of age and gender on thoracic vertebral body shape and disc degeneration: an MR investigation of 169 cases.
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There are limited data detailing the pattern of age and gender-related changes to the thoracic vertebral bodies and intervertebral discs. A retrospective MR investigation, involving T1-weighted midsagittal images from 169 cases, was undertaken to examine age influences on the anterior wedge (anteroposterior height ratio or Ha/Hp), biconcavity (midposterior height ratio or Hm/Hp), and compression indices (posterior height/anteroposterior diameter or Hp/D) of the thoracic vertebral bodies. Disc degenerative changes in the annulus, nucleus, end-plate and disc margin were noted on T2-weighted sagittal images for the 169 cases, based on a 3-level grading system. A linear age-related decline in the Ha/Hp and Hm/Hp indices was noted. The Hp/D index increased during the first few decades of life, then decreased gradually thereafter. The prevalence of abnormal findings in the annuli, nuclei and disc margins increased with increasing age, particularly in the mid and lower thoracic discs. Greater disc degenerative changes were observed in males. These findings provide further insight into the nature of thoracic vertebral shape changes across the lifespan, and the typical patterns of degeneration of the thoracic intervertebral discs. (+info)
Radicular involvement and medullary invasion from a malignant mesothelioma.
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We present the case of a 57-year-old patient who had worked at a fiber-cement factory for 28 years. The patient developed an epithelioid-type pleural mesothelioma 5 years after retiring, after he was diagnosed with asbestosis. Only 5 months after the diagnosis of mesothelioma, a medullar section appeared to be totally invaded by a tumor in the medullar canal, thus causing paraplegia and affecting the bladder and anal sphincters. The patient underwent radiotherapy and chemotherapy, and achieved partial recovery, but died 9 months after the diagnosis. (+info)
Intradural disc herniation at the T1-T2 level.
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Intradural disc herniations comprise 0.26-0.30% of all herniated discs. Five percent are found in the thoracic, 3% in the cervical, and 92% in the lumbar region. Although intradural disc herniation may be suspected on preoperatively made CT scans, myelograms, and MRI scans, establishing the diagnosis prior to the surgery is difficult. We present a case of the patient with severe neurological deficits, caused by intradural thoracic disc herniation at T1-T2 interspace, which required surgical treatment. The symptoms were relieved immediately after surgery. This is the first description of an intradural disc herniation at that level. (+info)
Questionnaire versus direct technical measurements in assessing postures and movements of the head, upper back, arms and hands.
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OBJECTIVES: This study compares questionnaire-assessed exposure data on work postures and movements with direct technical measurements. METHODS: Inclinometers and goniometers were used to make full workday measurements of 41 office workers and 41 cleaners, stratified for such factors as musculoskeletal complaints. The subjects answered a questionnaire on work postures of the head, back, and upper arms and repeated movements of the arms and hands (3-point scales). The questionnaire had been developed on the basis of a previously validated one. For assessing worktasks and their durations, the subjects kept a 2-week worktask diary. Job exposure was individually calculated by time-weighting the task exposure measurements according to the diary. RESULTS: The agreement between the self-assessed and measured postures and movements was low (kappa = 0.06 for the mean within the occupational groups and kappa = 0.27 for the whole group). Cleaners had a higher measured workload than office workers giving the same questionnaire response. Moreover, the subjects with neck-shoulder complaints rated their exposure to movements as higher than those without complaints but with the same measured mechanical exposure. In addition, these subjects also showed a general tendency to rate their postural exposure as higher. The women rated their exposure higher than the men did. CONCLUSIONS: The questionnaire-assessed exposure data had low validity. For the various response categories the measured exposure depended on occupation. Furthermore, there was a differential misclassification due to musculoskeletal complaints and gender. Thus it seems difficult to construct valid questionnaires on mechanical exposure for establishing generic exposure-response relations in epidemiologic studies, especially cross-sectional ones. Direct technical measurements may be preferable. (+info)
Can a short spinal cord produce scoliosis?
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Some patients with scoliosis have a relatively short vertebral canal. This poses the question of whether a short spinal cord may sometimes cause scoliosis. The present paper presents two observations that may support this concept. It presents a scoliosis model demonstrating what effect a short, unforgiving spinal cord might have on the spinal column. The model uses two flexible parallel tubes with the facility to tighten one. It demonstrates that a short, unforgiving spinal cord could produce the abnormal rotatory anatomy observed at the apex in scoliosis, with first lordosis, then lateral deviation and finally a rotation of the vertebral column, with the rotation occurring between the canal and the vertebral body, around the axis of the cord. The anatomy of the apical vertebra is described from two museum specimens, a computed tomography (CT) myelogram and seven magnetic resonance imaging (MRI) studies. The study confirms that the vertebral canal and the intervertebral foraminae retain their original orientation. The spinal cord is eccentric in the canal towards the concavity of the curve; the major component of rotation occurs anterior to the vertebral canal and the axis of this rotation seems to be at the site of the spinal cord. These observations do not establish that a short spinal cord will result in scoliosis, but the results are compatible with this hypothesis, and that impairment of spinal cord growth factors may sometimes be responsible for scoliosis. (+info)
Biomechanical compression tests with a new implant for thoracolumbar vertebral body replacement.
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The authors present an investigation into the biomechanical functioning of a new titanium implant for vertebral body replacement (Synex). Possible indications are fractures and/or dislocations with damage of the anterior column, posttraumatic kyphosis and tumors of the thoracolumbar spine. The construction must be supplemented by a stabilizing posterior or anterior implant. For best fit and contact with adjacent end-plates, Synex is distractable in situ. We performed comparative compression tests with Synex and MOSS ("Harms mesh cage") on human cadaveric specimens of intact vertebrae (L1). The aim of the study was to measure the compressive strength of the vertebral body end-plate in uniaxial loading via both implants to exclude collapse of Synex in vivo. Twelve human cadaveric specimens of intact vertebrae (L1) were divided into two identical groups (matched pairs) according to bone mineral density (BMD), determined using dual-energy quantitative computed tomography (DE-QCT). The specimens were loaded with an axial compression force at a constant speed of 5 mm/min to failure, and the displacement was recorded with a continuous load-displacement curve. The mean ultimate compression force (Fmax) showed a tendency towards a higher reading for Synex: 3396 N versus 2719 N (non-significant). The displacement until Fmax was 2.9 mm in the Synex group, which was half as far as in the MOSS group (5.8 mm). The difference was significant (P < 0.001). The compression force was twice as high, and significantly (P < 0.05) higher with Synex at displacements of 1 mm, 1.5 mm and 2 mm. A significant (P < 0.001) correlation (R = 0.89) between Fmax and BMD was found. Synex was found to be at least comparable to MOSS concerning the compressive performance at the vertebral end-plate. A possible consequence of the significantly higher mean compression forces between 1 and 2 mm displacement might be decreased collapse of the implant into the vertebral body in vivo. (+info)
The effect of surgery and remodelling on spinal canal measurements after thoracolumbar burst fractures.
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Bone fragments in the spinal canal after thoracolumbar spine injuries causing spinal canal narrowing is a frequent phenomenon. Efforts to remove such fragments are often considered. The purpose of the present study was to evaluate the effects of surgery on spinal canal dimensions, as well as the subsequent effect of natural remodelling, previously described by other authors. A base material of 157 patients operated consecutively for unstable thoracolumbar spine fractures at Sahlgrenska University Hospital in Gothenburg during the years 1980-1988 were evaluated, with a minimum of 5-years follow-up. Of these, 115 had suffered burst fractures. Usually the Harrington distraction rod system was employed. Patients underwent computed tomography (CT) preoperatively, postoperatively and at follow-up. From digitized CT scans, cross-sectional area (CSA) and mid-sagittal diameter (MSD) of the spinal canal at the level of injury were determined. The results showed that the preoperative CSA of the spinal canal was reduced to 1.4 cm2 or 49% of normal, after injury. Postoperatively it was widened to 2.0 cm2 or 72% of normal. At the time of follow-up, the CSA had improved further, to 2.6 cm2 or 87%. The extent of widening by surgery depended on the extent of initial narrowing, but not on fragment removal. Remodelling was dependent on the amount of bone left after surgery. The study shows that canal enlargement during surgery is caused by indirect effects when the spine is distracted and put into lordosis. Remodelling will occur if there is residual narrowing. Acute intervention into the spinal canal, as well as subsequent surgery because of residual bone, should be avoided. (+info)