Showing papers on "Cobb angle published in 1995"

Interobserver and intraobserver variability in interpretation of lumbar disc abnormalities. A comparison of two nomenclatures.

Abstract: Study Design. The transverse plane evolution of the most common idiopathic scoliosis deformities was studied using a cross-sectional database of 181 patients whose deformities were visualized by precise three-dimensional techniques. Objective. The objective was to test the hypothesis that for all common idiopathic scoliosis deformities evolution occurs as a torsion, the apex vertebra translating away from the upper end vertebra and at the same time angulating in a clockwise arc for right apex deformities and a counterclockwise arc for left apex deformities. Summary of Background Data. Perdriolle and Vidal proposed this hypothesis in 1987, which explained observations we had made in 1983 and which was partially supported in thoracic curves in our 1992 study. Methods. Deformities were characterized as single thoracic major, thoracic major and thoracolumbar or lumbar minor, double thoracic and thoracolumbar or lumbar major, and single thoracolumbar or lumbar major curves. The dependent variable studied was the coronal plane regional angular (Cobb) deformity. The independent variables studied were the lateral and anteroposterior translation of the apex vertebra in relation to the upper end vertebra, and the transverse plane translation and angulation of the apex vertebra in relation to the upper end vertebra. For the model or hypothesis to be true, the apex vertebra to upper end vertebra transverse plane translational distance and angular relationship should increase as the Cobb angle increases. Results. In relation to the upper end vertebra, the apex vertebra always translated laterally, almost always was accompanied by transverse plane translation increase, and usually was accompanied by transverse plane angulation increase. Anteroposterior translation was minimal, but for thoracolumbar and lumbar curves it tended to be posterior. Conclusion. The theory that these deformities evolve as torsions, with the apex vertebra translating away from the upper end vertebra and at the same time following a clockwise angular pathway to the upper end vertebra of right apex curves and a counterclockwise angular pathway for left apex curves is supported. Compensatory thoracolumbar and lumbar curves evolve in the same manner as major curves

Adolescent idiopathic scoliosis. Long-term effect of instrumentation extending to the lumbar spine.

Abstract: We evaluated eighty-three patients in whom adolescent idiopathic scoliosis had been treated with a posterior spinal arthrodesis and Harrington instrumentation extending to the second, third, fourth, or fifth lumbar vertebra. All eighty-three patients completed a questionnaire, and fifty-five patients were also examined clinically and roentgenographically at a follow-up evaluation at an average of twelve years (range, ten to sixteen years). Twelve patients had a type-I curve; twenty-six, a type-II curve; sixteen, a type-III curve; and one, a type-IV curve, according to the classification of King et al. The preoperative Cobb angle of the primary curve averaged 60 degrees and ranged from 40 to 100 degrees. The curve was an average of 35 degrees (range, 15 to 65 degrees) at the most recent follow-up evaluation. Functional assessment with use of information from the questionnaire revealed an average spine score of 81 points (range, 18 to 99 points). On the basis of the score, thirty-five patients were considered to have had an excellent result; twenty, a good result; thirteen, a fair result; and fifteen, a poor result. Sixty-three (76 per cent) of the eighty-three patients had low-back pain compared with thirty (50 per cent) of sixty individuals who served as a control group. This difference was significant (p < 0.001; chi-square test). Eighteen patients (22 per cent) needed additional spinal procedures. Fourteen patients (17 per cent) did not think that the goals of the initial operation had been accomplished.(ABSTRACT TRUNCATED AT 250 WORDS)

New prognostic factors to predict the final outcome of brace treatment in adolescent idiopathic scoliosis.

Abstract: Study design Eighty-five patients with adolescent idiopathic scoliosis treated with Milwaukee or thoracolumbosacral orthoses at The Duchess of Kent Children's Hospital were studied longitudinally at 4-6-month intervals until maturity for spinal curvature and vertebral rotation, or until termination of brace treatment for persons who experienced brace failure who went on to have surgery. Objectives To identify radiologic features so that it may be possible to predict outcome of brace treatment early on. Summary of background data The structural curve with poor flexibility and large rotational prominence have been found to be associated with poor prognosis for brace treatment. However, early response to bracing for spinal deformity and its relationship to final outcome of brace treatment in a longitudinal study is not available in the literature. Methods Vertebral rotation and Cobb angles measured from anteroposterior radiographs of the spine obtained before bracing and 1-2 months after bracing were found valuable for prediction. Changes in post-brace Cobb angle and vertebral rotation were considered as an increase or reduction only when there was an increase or reduction of minimum 5 degrees or more from their prebrace measurements. Results Those patients who showed increase in vertebral rotation and/or in Cobb angle after brace application were shown to have progression of curves leading to brace failure in 93% of patients, and 79% of these required surgery. The patients with no change in both vertebral rotation and Cobb angle after bracing often experienced brace failure (69%). Two patients (15%) required surgery. The results show that reduction of both Cobb angle and vertebral rotation after application of a brace is a prognostic indicator for a good outcome (97%), and no patients required surgery. Most of the patients with lumbar scoliosis (91%) showed such reductions. Conclusion The findings show a strong association between changes in vertebral rotation and the Cobb angle after application of a brace and the final outcome. Reduction in both is indicative of a good outcome, whereas increase in one or both indicates brace failure.

Variability in Cobb angle measurements in children with congenital scoliosis

Abstract: The variability in measurement of angles in congenital scoliosis is not known, but it is postulated that it is larger than that in adolescent idiopathic scoliosis due to skeletal immaturity, incomplete ossification, and anomalous development of the end-vertebrae. To determine this variability, we selected 54 radiographs of adequate quality showing 67 scoliotic curves from children with congenital scoliosis. The end-vertebrae were preselected. Each curve was measured by the Cobb method on two separate occasions by six different observers, using the same goniometer and marker. The intraobserver variability was +/- 9.6 degrees and the interobserver variability +/- 11.8 degrees. If 'significant progression' is to be used as a criterion for surgical fusion in congenital scoliosis, there should be at least a 23 degrees increase, the entire range of the interobserver variability, in the curvature to ensure that the perceived increase is not due to variability in measurement.

Variability of geometric measurements from three-dimensional reconstructions of scoliotic spines and rib cages

Abstract: Three-dimensional (3-D) reconstructions of the spine are being used with increasing frequency to describe scoliotic deformities, but the reproducibility of most of these techniques and the implication for the reliability of measurements made on the reconstructions has not been reported. How reliable are these reconstructions, and can a clinician interpret with confidence the results of studies based on such mathematical models? A reproducibility study of various computerised measurements obtained from 3-D reconstructions of the spine and rib cage for five subjects with adolescent idiopathic scoliosis was done to evaluate the errors associated with repeated measurements and compare them with inter-and intraobserver errors reported for similar commonly used clinical measurements. The mean variation for the Cobb angle differed according to the plane of computation from 0.6° in the frontal plane to 6.7° in the sagittal plane; vertebral axial rotation varied from 2.3° to 5.9° according to the vertebral level, and rib hump measurements displayed an average variation of 1.4°. All these variations are below or within the error levels reported for equivalent 2-D measurements used by clinicians, which suggests that this 3-D model of idiopathic scoliosis may be used with confidence for clinical evaluations.

Long-term results of combined anterior and posterior convex epiphysiodesis for congenital scoliosis due to hemivertebrae.

Abstract: Study Design. Retrospective review of patient records with recent clinical and radiologic assessment. Objective. To evaluate the long-term result of anterior and posterior convex epiphysiodesis in the management of congenital scoliosis resulting from fully segmented nonincarcerated hemivertebra. Summary of Background Data. Thirty patients (16 male/14 female patients) were reviewed. Follow-up was a minimum of 3 years (average, 8 years 10 months ; range, 3-22.5 years). Nineteen patients were skeletally mature, and the mean age of the remaining 11 was 11.75 years. Method. Clinical evaluation and sequential measurements of Cobb angle was made independently by two observers. Results. Compared with preoperative values, the rate of change in Cobb angle was reversed in 23 patients, arrested or slowed in five patients, and unchanged or progressed in two patients. The annual rate of change in Cobb angle was +1.9° before surgery and -1.2° after surgery, a difference of 3.1°. This is highly statistically significant (P < 0.001). Total correction in Cobb angle correlates with age at time of surgery (P < 0.03). The rate of correction in Cobb angle after surgery correlates with the total correction achieved (P < 0.001) and with age at time of surgery (P< 0.05). The greater correction is achieved when surgery is performed at a young age. The preoperative rate of increase in Cobb angle does not correlate with correction (P < 0.76). The site of the hemivertebrae influenced final outcome with best results in the lumbar spine. Conclusion. Combined anterior and posterior convex epiphysiodesis is a reliable method for the correction of deformity resulting from hemivertebrae.

Pediatric cervical-spine immobilization: achieving neutral position?

Abstract: This study was designed to evaluate prospectively the ability of current spine-immobilization devices to achieve radiographic-neutral positioning of the cervical spine in pediatric trauma patients. All trauma patients who required spinal immobilization and a lateral cervical spine radiograph were included in the study. A lateral cervical spine radiograph was obtained while the child was immobilized. The Cobb angle (C2-C6) was measured using a handheld goniometer. The method of immobilization, age at injury, and Cobb angle were compared. One hundred and eighteen patients with an average age of 7.9 years were enrolled. The majority were males (71%). The most frequent mechanisms of injury included motor vehicle accidents (35%) and falls (32%). The average Glascow Coma Scale score was 14. Although 31% of the children complained of neck pain, 92% were without neurologic deficits. The Cobb angles ranged from 27 degree kyphosis to 27 degree lordosis, and only 12 of the patients presented in a neutral position (0 degrees). Greater than 5 degrees of kyphosis or lordosis was observed in 60% of the children. Thirty-seven percent of the patients had 10 degrees or greater angulation. The most frequent methods of immobilization included a collar, backboard, and towels (40%), and a collar, backboard, and blocks (20%), but these techniques provided < 5 degrees kyphosis or lordosis in only 45% and 26% of the children respectively. No single method or combination of methods of immobilization consistently placed the children in the neutral position.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term results of convex epiphysiodesis for congenital scoliosis.

Abstract: The objective of this study was to evaluate the long term outcome of combined anterior and posterior convex spinal epiphysiodesis in the treatment of congenital scoliosis. The study covered 53 patients (27 male, 26 female) with a minimum follow up period from surgery of 3 years (mean 8.8 years, range 3–22.5 years). Of these, 34 were skeletally mature when reviewed. Clinical assessment and sequential measurement of Cobb angles were used to chart the course of the deformity following surgery. The types of vertebral anomalies encountered were: 4 unsegmented bars, 7 unsegmented bars with hemivertebrae, 30 hemivertebrae (of which 2 were double hemivertebrae) and 12 complex (unclassifiable) patterns. The severe types were concentrated in the thoracic spine. Results are presented with reference to the type and site of anomaly and to the age of the patient at the time of surgery. Where deformity was due to an unsegmented bar (with or without hemivertebra) the rate of change of Cobb angle was slowed, but not reversed, following surgery, For the complex anomalies there was a reduction in the rate of progression of deformity following surgery, however, the final Cobb angle still increased from a mean of 61° to 70°. In contrast, the rate of progression reversed or slowed in 97% of the hemivertebra patients following surgery, producing a change in mean Cobb angle from 41° pre-operatively to 35° post-operatively. For each type of anomaly the correction achieved was greater where the surgery was performed at a younger age. Final outcome was influenced by the site of anomaly, with a better correction being achieved in the lumbar than the thoracic spine. In conclusion, we feel that convex epiphysiodesis has an important role in the surgical management of congenital scoliosis and, for hemivertebrae in particular, it can produce significant correction of deformity.

Cotrel-Dubousset and Harrington Instrumentation in idiopathic scoliosis: a comparison of long-term results.

Abstract: Between 1968 and 1977, 72 patients with idiopathic scoliosis underwent Harrington Instrumentation (HI). Between 1985 and 1988, 21 patients with idiopathic scoliosis had posterior spinal fusion with Cotrel-Dubousset instrumentation (CDI). All patients were operated by the same orthopedic surgeon. None of the CDI patients had postoperative brace or cast protection, the HI group had on average 6 months' postoperative brace treatment. The two groups of patients were comparable in age, sex, and type of curves. The HI group and CDI group were reexamined with clinical and radiological assessment after mean periods of 148 months and 60 months respectively. The average preoperative Cobb angle in the CDI group was 59.9° (HI group 67.8°), which improved to 20.8° (HI group 33°) postoperatively — a correction of 66.3% (HI group 51.3%). The loss of correction on reassessment amounted to 5% in the CDI group and 20.7% in the HI group. In both groups, the mean rib hump height was reduced to 2.2 cm. In 40% of the Harrington patients, a flat back was found, but this was not related to clinical back pain. The rate of complications and reintervention was 9.5% in the CDI group and 8.3% in the HI group. There were no neurological complications. Subjectively, 86% of the Harrington patients and 95.2% of the CDI patients rated the results of their operation as “good” or “very good”. The CDI group showed better results in correction of the Cobb angle and loss of correction, while saving one mobile lumbar segment. The correction of the rib hump showed the same results for both techniques. Blood loss and operation time was much lower in the HI group. However, the rate of complications was similar in both groups.

Mechanical performance of the Dick internal fixator: a clinical study of 75 patients

Abstract: A consecutive series of 75 patients with fractures of the thoracolumbar spine, stabilized with the Dick internal fixator, was studied retrospectively. Posttraumatic kyphosis was measured on the preoperative lateral radiograph by the Cobb angle and the wedge angle and the results were compared with angles measured on the radiographs after instrumentation and after removal of the implants. The presence and number of broken Schanz screws was noted. In the whole group, an average correction of kyphosis of 15.5 degrees was obtained, but 7.6 degrees was lost again at follow-up. In comparing the kyphotic angle with the wedge angle, we found that this loss was almost exclusively situated in the upper intervertebral disc space. In the group of patients with transpedicular intravertebral bone grafting, the relative loss of correction in the wedge angle was smaller than in the group without bone grafting, while the relative loss of correction of the kyphotic angle was similar. Schanz screw breakage was present in 13.3% of patients, occurring in 4.6% of inserted screws. In the group of patients with broken Schanz screws, the loss of correction in the wedge angle was somewhat higher, but not markedly different from that of the patient group without breakage of screws. Risk of screw breakage was enhanced by laminectomy and reduced by transpedicular bone grafting. Screw breakage or important loss of correction did not influence the neurological outcome of the patients. The Dick internal fixator is a very reliable implant, even in patients with highly unstable fractures.(ABSTRACT TRUNCATED AT 250 WORDS)

Accuracy and applicability of measurement of the scoliotic angle at the frontal plane by Cobb's method, by Ferguson's method and by a new method

Abstract: A new method for the measurement of scoliotic curves in antero-posterior (AP) radiographs is presented, in which the centre of the surface image of the vertebral bodies of the apical and two end vertebrae of the curvature are defined on the basis of geometric principles. Measurements using the Cobb, the Ferguson, and the new method were performed on ten AP radiographs from each of three groups of young patients with right convex thoracic idiopathic scoliosis with Cobb angles of between 7 and 15 degrees, 16 and 45 degrees and 46 and 80 degrees, respectively. Measurements using the Cobb method yielded significantly higher values than measurements using either the Ferguson method or the new method. In curves with Cobb angles of between 7 and 15 degrees, the values using Ferguson's method were significantly lower than those using the new method; the difference increased significantly in curves with a Cobb angle of 16 degrees or more. The level of significance of the intra- and interobserver differences between the new, the Cobb and the Ferguson methods was significantly higher in curves with a Cobb angle of 16 degrees or more. It is argued that measures of the scoliotic angle obtained by the new method are of greater clinical relevance than those obtained by the two other methods. Unlike the Cobb method, the new method takes into consideration the translation of the apical vertebra in relation to the end vertebrae and not only the tilt of the end vertebrae of the curve. As compared to the Ferguson method, the new method is based on standardised geometric principles, and is not influenced by changes in the shape of the vertebral body. Moreover, the repeatability of the new method is greater than that of both the Cobb method and the Ferguson method. Therefore, it is believed that the new method provides a more accurate measure of the scoliotic curve than do the two other methods, and it is to be preferred over the other two methods in longitudinal evaluation of the development of the curve.

Vertebral rotation and pedicle length asymmetry in the normal adult spine.

Abstract: Rotation in the horizontal plane of vertebra T8, T9 or T10 was determined on CT scans of 25 male and 25 female patients with normal spines. The pedicle length was measured using a new method, and the right/left pedicle length index was calculated. In 38 (76%) of the patients there was vertebral rotation to the right with a mean Cobb angle of 3.0 degrees, and in 4 (8%) rotation to the left, mean Cobb angle 2.2 degrees (P < 0.01). In 8 (16%) there was no measurable rotation. The pedicle length index was greater than 1.05 in 9 subjects, between 0.95 and 1.05 in 16 and less than 0.95 in 25, indicating a predominance of longer pedicles on the left side. In 21 out of the 38 patients with vertebral rotation to the right, the left pedicle was longer than the right one (P < 0.01). The results indicate that the normal spine is afflicted with a vertebral rotation to the right in association with a longer pedicle on the left. The significance of these observations for the pathogenesis of idiopathic scoliosis remain uncertain.

Does bracing affect bone density in adolescent scoliosis

Abstract: Study Design. This is a case-control, cross-sectional analysis of bone density. Objectives. To determine if bracing during growth affects bone density in adolescent idiopathic scoliosis and whether the effect is local or systemic. Summary of Background Data. Data concerning the effect of bracing on bone mass in adolescents with idiopathic scoliosis are nonexistent. We were concerned that bone mass loss resulting from long-term brace use may be permanent and may predispose to problems with osteoporosis. Methods. Healthy adolescent females (n=85) with scoliosis measuring 20-45° and treated either by brace or observation were studied. Dietary calcium, activity level, body mass index, and pubertal status were evaluated. Scoliosis was measured by Cobb angle. Bone mineral density at the hip and spine were measured by dual energy x-ray absorptiometry to differentiate local versus systemic effects of bracing. Lateral scans of the L3 vertebral body were used to minimize the influence of the pedicles, the effect of the scoliosis, and the interference of the ilium. Results. Mean age, height, and weight were similar between braced and observed groups. After adjusting for curve, Cobb angle, body mass index, activity, and diet, two-way analysis of covariance showed L3 and femoral bone mineral density was the same for braced and observed patients, and pubertal status affected spinal bone mineral density but had no effect on femoral bone mineral density and was not affected by brace use. Cobb angle, curve pattern, activity, and diet were not associated with bone mineral density. Conclusion. Brace treatment does not adversely affect bone mass at the spine and hip in children with idiopathic scoliosis

Structural vertebral changes in the horizontal plane in idiopathic scoliosis and the long-term corrective effect of spine instrumentation.

Abstract: The rotation and structural changes of the apex vertebra in the horizontal plane as well as of the thoracic cage deformity were quantified by measurements on computed tomography (CT) scans from patients with right convex thoracic idiopathic scoliosis (IS). The CT scans were obtained from 12 patients with moderate scoliosis (mean Cobb angle 25.8°, r 13°–30°) and from 33 with severe scoliosis (mean Cobb angle 46.2°, r 35°–71°). In addition, CT scans of thoracic vertebrae from 15 patients without scoliosis were used as reference material. Ten of the scoliotic cases had had Cotrel-Dubousset instrumentation (CDI) and posterior fusion and had entered a longitudinal study on the effect of operative correction on the re-modelling of the apical vertebra. An increasingly asymmetrical vertebral body, transverse process angle, pedicle width and canal width were found in the groups with scoliosis as compared with the reference material. Vertebral rotation and rib hump index were significantly larger in patients with early and advanced scoliosis than in normal subjects. The modelling angle of the vertebral body, the transverse process angle index and the vertebral rotation in relation to the middle axis of the thoracic cage were significantly greater in patients with severe than with moderate scoliosis. The results of this longitudinal study suggest that the structural changes of the apical vertebra regress 2 years or more after CD instrumentation.

School screening for scoliosis: the value of quantitative measurement

Abstract: Several studies advocate quantification of the bending test or performing surface topography to reduce the referral rate and to increase the specificity of the bending test in screening for scoliosis. Within the framework of a school screening project all children with a positive bending test were reexamined with measurement of rib hump height, angle of trunk rotation and moire topography. In the period 1983-1986, out of three cohorts of 10,000 children of 10, 12 and 14 years of age, 3,069 were reexamined, of whom 1931 again tested positive (63%). The value of the three techniques in terms of sensitivity and specificity within the reexamined group was evaluated with regard to the Cobb angle on a spinal radiograph, which was made in 671 cases. A reduction in referrals of 37% was found. No significant difference in the ability to detect scoliosis was found between the three techniques mentioned. It is concluded that measurement techniques are valuable in school screening programmes. In particular, if instead of a single cut-off value, a range within which the examination should be repeated is chosen, high sensitivity and high specificity can be combined. Angle of trunk rotation measurement seems to be the easiest method of screening.

Evaluation of deformities and pulmonary function in adolescent idiopathic right thoracic scoliosis

Abstract: Seventy patients with adolescent idiopathic right thoracic scoliosis had full assessment of their pulmonary function using a computerised pulmonary function system Their mean age at evaluation was 138 years The following measurements were obtained from anteroposterior and lateral standing and antero-posterior supine bending radiographs: lateral curvature, vertebral rotation, kyphosis, maximum sterno-vertebral distance and apical rib-vertebral angles Using the above measurements, the flexibility of curve, vertebral rotation and rib-vertebral angle asymmetry were calculated Patients were classified into three groups on the basis of their predicted vital capacity, to determine whether radiological features of deformity can help identify patients with compromised pulmonary function The mean Cobb angle and vertebral rotation for the 70 patients were 50° (range 35–100°) and 22° (range 1–44°) respectively The mean flexibility of curve and vertebral rotation were 52% and 49% respectively Mean thoracic kyphosis was 25%, ranging from -7 to 55% Of the patients with Cobb angle less than 90%, 71% had vital capacity less than 80% of predicted values, and of these, 18% had marked compromise of vital capacity (less than 60% of predicted values) Mean values of Cobb angle, vertebral rotational flexibility, kyphosis, rib-vertebral angle asymmetry (in standing as well as supine bending radiographs) differed significantly between patients with more than 80% of predicted vital capacity and those with 60% or less of predicted values Radiological features indicative of better pulmonary function were: rotational flexibility exceeding 55%, rib-vertebral angle asymmetry (standing) less than 25% and kyphosis greater than 15% Two deformity parameters—that give a better prediction of pulmonary function than the widely used Cobb angle, vertebral rotational flexibility and rib-vertebral angle asymmetry—were identified in this study

Scoliosis in familial dysautonomia. Operative treatment.

Abstract: The results of operative treatment of scoliosis were reviewed for twenty-two patients (ten boys and twelve girls) who had familial dysautonomia, an autosomal recessive disorder affecting primarily Ashkenazi Jews. The indication for operative intervention was progressive kyphoscoliosis to 45 degrees or more in a skeletally immature patient for whom bracing had failed. The mean age at the time of the operation was fifteen years and five months (range, eight years and two months to nineteen years). Seventeen patients had a thoracic curve with a mean preoperative Cobb angle of 69 degrees (range, 47 to 112 degrees), and five patients had a double major curve with a mean preoperative Cobb angle of 71 degrees (range, 42 to 87 degrees) for the cephalad curves and 60 degrees (range, 45 to 72 degrees) for the caudad curves. Twenty patients had a rigid kyphosis; in fourteen, the apex was at the seventh thoracic vertebra or more cephalad. Two patients had a lordoscoliosis. The mean preoperative kyphosis was 64 degrees (range, 12 to 110 degrees) in the thirteen patients who had a thoracic curve and for whom information regarding kyphosis was available, and it was 70 degrees (range, 54 to 84 degrees) in the five patients who had a double major curve. Postoperior spinal arthrodesis and instrumentation was performed in all patients. Two patients had an anterior arthrodesis as well because of the severity and rigidity of the curve. Allograft bone was used in eighteen patients. Postoperatively, all patients were managed with a body cast or with a custom-molded thoracolumbar brace.(ABSTRACT TRUNCATED AT 250 WORDS)

Trunk deformity in scoliosis studied by surface measurement

Abstract: Ihe three-dimensional back surface shape of 504 patients with untreated idiopathic scoliosis was studied using moire topography. A new system for the quantitative analysis of moire pictures was developed with the aid of a still video photo system and microcomputer system. With these systems, the outcome of the analysis can be obtained immediately at the clinical scene. Using a positioning device that restrained the movement of the patient's pelvis at the time of taking the moire picture, the reproducibility error was very small. The relationship of the parameters from the surface measurements with the radiographic appearance was then examined. The hump sum (HS), that is the sum total of the hump indices on three levels of the back was used as an index that represented the severity of the trunk deformity. It was possible to estimate objectively from HS, the correction in trunk deformity obtained after treatment. There was a relatively weak but statistically significant number of cases in which the degree of hump and that of the lateral curvature did not agree. Those within the range of one standard deviation from the regression line were defined as the standard rotation group, and those out of this range as the nonstandard rotation group. In the standard rotation group, the progression in curvature could be detected by moire analysis so that exposure to radiation could be reduced. In the nonstandard rotation group, radiographic examination remained necessary, although the magnitude of the trunk deformity itself could be estimated more accurately by HS. The discrepancy between the HS and the Cobb angle suggested that scoliosis and rib deformity were independent from each other, and therefore they should be evaluated separately.

Electrical muscle stimulation on the spine. Three-dimensional effects in rabbits.

Abstract: We investigated the 3-dimensional effect of electrostimulation of the latissimus dorsi, the erector spinae and the intercostal muscles on spinal configuration in 16 New Zealand white rabbits. Electrostimulation on the right side of the spine resulted in a left convex, hypokyphotic curve and vertebral body rotation towards the convexity of the curve in all rabbits. The Cobb angle in the coronal plane increased with stimulation of each of the muscles examined. The kyphosis decreased with stimulation of the latissimus dorsi and the erector spinae. The vertebral rotation increased with stimulation of all muscles. Stimulation of the tested muscles resulted in the simultaneous occurrence of a 3-dimensional spinal deformity with the characteristics of idiopathic scoliosis.

Scoliosis as the first sign of a cystic spinal cord lesion.

Abstract: We reviewed the cases of ten patients with scoliosis as the first sign of a cystic spinal cord lesion with the aim of identifying and studying early patient and curve characteristics. All patients were examined with magnetic resonance (MR) imaging of the brain and spinal cord and quantitative thermal testing (QTT). The mean Cobb angle was 22 degrees and the curves were right thoracic in seven patients, left thoracic in two, and left lumbar in one, when first seen for scoliosis. In six patients the cystic lesion was found in routine screening for syringomyelia, which is performed in all cases of congenital and juvenile scoliosis and in adolescent scoliosis before bracing. In four patients, it took up to 17 years following the initial diagnosis of scoliosis before neurologic deterioration warranted MR imaging, disclosing two Chiari I associated syrinxes and two cystic spinal cord tumors. QTT revealed a subclinically decreased sensation in two of the patients with no findings other than scoliosis. It also verified the decreased sensation in all patients in whom neurologic deterioration had complicated the clinical course of their scoliosis. More frequent spinal MR screening of patients with supposed juvenile or adolescent idiopathic scoliosis is indicated, regardless of curve type, to exclude a neurogenic cause. QTT documents subclinical as well as overt decreased sensation, and is valuable in the serial follow-up of these patients to monitor the progress or the response to treatment of the cystic lesion.

Effects of the combined VDS-Zielke and Harrington operation on the frontal rib cage deformity of double major curves in idiopathic scoliosis.

Abstract: Study Design. This study analyzed the changes in the frontal plane of the deformed lower rib cage and the scoliosis-related alterations on the spine in patients with double major curve-pattern idiopathic scoliosis. Objectives. The results obtained preoperatively, after the Zielke operation, postoperatively after the Harrington instrumentation, and at the follow-up evaluation were compared to investigate which changes of the elements of the rib cage deformity are caused by each of the two instrumentations. Summary of Background Data. Previously, Wojcik reported on the effects of a Zielke operation on the lower rib in mild S-shaped idiopathic scoliosis. No previous data exist regarding the lower rib cage deformities in severe idiopathic double major-pattern scoliosis and their changes after combined VDS-Zielke and Harrington instrumentation. Methods. Fifteen patients who underwent the staged Zielke operation followed by Harrington rod instrumentation were followed-up for an average period of 31.1 months. The methods used in our study included Cobb angle and a segmental analysis (T7-T12) of each of convex and concave rib-vertebra angles, rib-vertebra angle differences, vertebral rotation, and vertebral tilt. Results. In this series, the apical convex ribs showed an increased droop preoperatively compared with the concave apical ribs. The VDS-Zielke operation corrected the lumbar scoliosis in an average of 63% of patients, whereas the thoracic scoliosis showed an immediate spontaneous correction of 30%. The VDS-Zielke operation also produced a significant correction of the scoliosis-related vertebral tilt (T10-T12), derotated the lumbar vertebrae and the T12 vertebra significantly, elevated the mobile concave ribs, and increased the droop of the lower (T11, T12) mobile convex ribs. The Harrington instrumentation did not change the vertebral rotation, the vertebral tilt, the convex rib-vertebra angle, or the L4 obliquity, but significantly changed the apical concave rib-vertebra angle. The combined Zielke-Harrington instrumentation reduced the thoracic kyphosis and the thoracolumbar junction-kyphosis significantly, whereas the lumbar lordosis remained practically unchanged. Conclusions. Only the anterior VDS-Zielke instrumentation significantly corrects severe spinal deformities, elevates the three lower ribs on the concavity, and increases the droop of the two lower ribs on the convexity in the severe idiopathic double major curve-pattern scoliosis combined operated (Zielke-Harrington). Therefore, the Harrington instrumentation should have only limited use in cosmetic scoliosis surgery and should be replaced with posterior multi-hook instrumentation with a derotation effect.

Parameter variation in stable scoliosis.

Abstract: The reliability of scoliosis parameters such as the Cobb angle, the angle of trunk rotation and moire topography is known from several publications. These studies concern intra- and interobserver variations; they are in general of transversal nature, which means that measurements were performed on the same subject within a short time period. From clinical experience it appears that these variations may be greater when scoliosis patients are followed over several years. In order to determine the parameter variation in the follow-up of children with scoliosis, a retrospective study was undertaken. From among our outpatient population, 41 children with stable scoliosis over a period of at least 2 years were selected. Stable scoliosis was defined as a spinal deformity which, in retrospect, had not deteriorated during at least a 2-year period prior to the end of growth. Hence no indication for treatment was found for this group. The measurements of the angle of external trunk rotation, moire topography and Cobb angle of these children during the follow-up period were submitted to statistical computations using one-way analysis of variance. Variations in the results of Cobb angle measurement and the measurement of the angle of trunk rotation were found to be no different to the variations in intra- and interobserver measurements as reported mainly from transversal studies. The variation found in moire topography, in moire contour lines and in angle moire determination, was, however, considered too great for measurements to be reliable. In conclusion, only Cobb angle determination and external measurement of trunk rotation can be accepted as valid follow-up parameters from a methodological viewpoint.

Augmentation of ventral derotation spondylodesis according to Zielke with double-rod instrumentation : preliminary report on two-year results of thoracolumbar curves

Abstract: The advantages of VDS according to Zielke with excellent 3-dimensional correction and shorter fusion levels in comparison to posterior instrumentation techniques are well known. A disadvantage is the necessity of long postoperative immobilization in a body cast or brace due to lack of primary stability. The aim of the VDS double-rod instrumentation is augmentation of the system with the possibility of postoperative treatment without plaster cast or braces. Following thoracolumbophrenotomy and ligation of the segmental vessels double-hole vertebra clamps are inserted. First VDS screws are placed in the posterior holes of these plates. With a 4-mm threaded compression rod correction is obtained by centripetal compressive forces on the nuts. Next VDS screws for the 5-mm threaded rod are inserted into the anterior holes of the vertebral clamps. The rod is implanted in a slightly compressive manner and augments the system. In a prospective study 8 patients, 4 with idiopathic and 4 with neuromuscular scoliotic deformities, underwent this surgical procedure and now have a follow-up of 2 years. Curves ranged from 45 degrees to 131 degrees Cobb angle. All patients were treated without plaster casts or braces postoperatively, but with only a semielastic vest for 4 to 6 months. Unusual intra- and postoperative complications have not been noted. Correction of the primary curve averaged 69.4% at follow-up. Tilt of the caudal end vertebra was corrected 75% to an average of 6.3 degrees. Spontaneous partial correction of the upper secondary curve was noted in all cases. Rod fracture of the 5-mm rod without fracture of the 4-mm rod at this level was seen in 1 patient without loss of correction. Solid fusion was achieved at every level in all patients. The sagittal plane was not adversely affected by the instrumentation. However, larger patient numbers and a longer follow-up are necessary.

[Idiopathic scoliosis by spinal fusion and brace treatment: evaluation by gait analysis].

Abstract: UNLABELLED We have investigated the differences in gait between 68 idiopathic scoliosis patients and 186 normal subjects, and differences in gait before and after treatment of the scoliosis by two different methods. The idiopathic scoliosis patients were divided into two groups according to which treatment they had received; one group of 17 cases had been treated by spinal fusion and the other group of 51 cases had been treated by bracing. Gait analysis was performed using a 1.2 m wide and 10.8 m long force plate walkway. Three components of each step (the lateral, horizontal and vertical components) were measured. Gait velocity, step length, step width and cadence were evaluated as temporal and distance factors, and symmetry, reappearance, smoothness, sway, rhythm and impact were evaluated as gait factors. RESULTS Before treatment, there was no difference in any temporal or distance factor between the scoliosis patients and the normal subjects. However, the index of symmetry, and of sway, in the vertical component prior to treatment in the scoliosis patients was significantly inferior to that in the normal subjects. A positive correlation was found between the index of sway in the vertical component and the pretreatment Cobb angle. This correlation was found in the right-convex single curve group and in the double curve group, but not in the left-convex single curve group. After spinal fusion, the step width became wider and the index of sway significantly improved, but index of symmetry was unchanged. No gait factor became worse postoperatively. In contrast, in the bracing group, the step width became wider, but the index of symmetry, and of sway in the vertical component, did not improve with the brace. The gait of scoliosis patients could be objectively and quantitatively analyzed by the force plate. The gait analysis was useful for evaluating the effects of spinal fusion, and of brace treatment, in idiopathic scoliosis patients.

Three-Dimensional Morphological Modeling of Scoliotic Spine.

Abstract: Scoliosis is a spinal deformity that is defined as a pathological frontal curvature with decrease of the physiological sagittal curvature, and must be evaluated three-dimensionally. We present a morphologic curve to express the three-dimensional configuration of a scoliotic spine from two plane radiograms, and evaluate spinal curvature three-dimensionally. The morphologic curve can be formulated from two plane curves approximating the frontal and sagittal arrangements of the centers of vertebral bodies. Furthermore, the Cobb angle, which is widely used in orthopaedics, can be calculated three-dimensionally as the maximum angle between two tangent vectors of the morphologic curve. In 45 spines with idiopathic scoliosis, the configurations of spines were extremely well approximated by the morphologic curves. Three-dimensional Cobb angle was significantly larger than frontal Cobb angle. Since the three-dimensional Cobb angle includes the sagittal and frontal curvatures, it can be used for three-dimensional evaluation of the scoliotic spine.

External Fixation in Experimental Scoliosis

Abstract: The purpose of this experimental study was to investigate the effects of spinal external fixation in scoliosis. Two of four ribs on the right side of growing rabbits were partially resected. Between 4 and 6 weeks later, moderate right-convex thoracic scoliosis had developed. Then, in seven rabbits, a mini-Orthofix or fixano fixator was attached by Kischner wires to T9/10 and L1/2. The average Cobb angle was 27.1 degrees before external fixation, and was 13.6 degrees at initial correction just after attaching the fixator. In three of these, the fixators were removed at more than 8 weeks after the operation. Only slight progressive vertebral curvature was seen in these rabbits after removal of the fixator, with a relatively good effect of prophylaxis of progression compared to the controls. We propose that the effects of this spinal external fixation for scoliosis was due to correction of the axial rotation at the apical vertebra rather than to the traction force.