Showing papers on "Cobb angle published in 1990"

Measurement of the Cobb angle on radiographs of patients who have scoliosis. Evaluation of intrinsic error.

Abstract: To quantitate the intrinsic error in measurement, fifty anteroposterior radiographs of patients who had scoliosis were each measured on six separate occasions by four orthopaedic surgeons using the Cobb method For the first two measurements (Set I), each observer selected the end-vertebrae of the curve; for the next two measurements (Set II), the end-vertebrae were pre-selected and constant The last two measurements (Set III) were obtained in the same manner as Set II, except that each examiner used the same protractor rather than the one that he carried with him The pooled results of all four observers suggested that the 95 per cent confidence limit for intraobserver variability was 49 degrees for Set I, 38 degrees for Set II, and 28 degrees for Set III The interobserver variability was 72 degrees for Set I and 63 degrees for Sets II and III The mean angles differed significantly between observers, but the difference was smaller when the observers used the same protractor

Measurement of scoliosis and kyphosis radiographs. Intraobserver and interobserver variation.

Abstract: Interobserver variations for measurements of the Cobb angle on radiographs of patients who had kyphosis were comparable with those on the radiographs of patients who had scoliosis. Four staff orthopaedists and one physical therapist measured eight radiographs that showed scoliosis and twenty that showed kyphosis. The measurements were made on two occasions and in random order. For scoliosis, the average difference between readings was 3.8 degrees, and 95 per cent of the differences were 8 degrees or less (range, 0 to 10 degrees). These findings were in keeping with those of other published reports. For kyphosis, the average difference between readings was 3.3 degrees, and 95 per cent of the differences were 7 degrees or less (range, 0 to 30 degrees). One investigator rated the kyphosis radiographs with respect to clarity. There was a trend to less variation with clearer radiographs, but this was not significant. The end-vertebrae were pre-selected for some radiographs and were freely chosen by the interpreter for others. Reliability was not significantly improved when the end-vertebrae of the curve had been pre-selected. Using the statistical method called tolerance limits, we determined that if one were to be 95 per cent confident that a measured difference represented a true change, the difference would have to be 10 degrees for scoliosis radiographs and 11 degrees for kyphosis radiographs. The probability that a measured difference is due to measurement error alone (that is, a false-positive reading) was calculated.

Validity and Reliability Testing of the Scoliometer

Abstract: This study was designed to evaluate the Scoliometer®, an instrument that measures axial trunk rotation in individuals with scoliosis. The objectives included determining 1) the Scoliometer's® screening capability and validity and 2) the intrarater and interrater reliability of Scoliometer® measurements. Scoliometer® measurements made by two raters on 65 persons with idiopathic scoliosis were correlated with radiographic assessment of vertebral (pedicle) rotation and lateral curvature (Cobb method). Correlations ranged from .32 to .46 with pedicle rotation and from .46 to .54 with the Cobb angle. Frequency analysis revealed relatively good specificity, sensitivity, and predictive capability of the Scoliometer®. Intrarater and interrater reliability coefficients were high ( r = .86–.97). These results indicate good measurement reproducibility. The less-than-optimal between-method correlation coefficients suggest that the validity of Scoliometer® measurements is not sufficient to use this method alone for determining patient diagnosis and management. Based on the positive-frequency analysis, however, the use of this tool as a screening device would be appropriate.

A comparison of radiographic and computer-assisted measurements of thoracic and thoracolumbar sagittal curvature*

Abstract: Sagittal plane curve characteristics of the thoracolumbar spine were evaluated from 286 lateral chest radiographs comparing the Cobb technique with a computer-aided digitizer. Thoracic kyphosis and curve apex were measured from the T3 to T11 segments, and in 120 cases, the level of the thoracolumbar curve inflexion point was determined. An age-related increase in curve magnitude was similar for both measurements, although computer generated kyphosis angles were generally larger. The apex of thoracic kyphosis was consistently located near T7 for males compared with greater variability with age for females. The thoracolumbar inflexion point shifted caudally with increasing years, being most marked for females. The computer method was more reliable, producing a coefficient of variation of 1.4% on repeated measurement. The ability to describe quantitatively the thoracolumbar curve characteristics, calculate angles between selected segments, determine points of inflexion and maximum curvature, indicates that radiographic evaluation of sagittal spinal curvature is improved with the use of computer-aided measurement.

Measurement variations in scoliotic angle, vertebral rotation, vertebral body height, and intervertebral disc space height.

Abstract: Thirty consecutive posteroanterior and lateral radiographs of patients with adolescent idiopathic scoliosis with a mean Cobb angle of 24.4 degrees were read. In measuring the scoliotic angle, the interobserver error (SD) was 2.8 degrees and the intraobserver, 1.8 degrees. Rotation of the apical vertebra was estimated by measuring the translation of the pedicle on posteroanterior radiographs. For vertebral rotation, the interobserver measurement error (SD) was 3.4 and the intraobserver, 1.8%. The height of the apical vertebral body and the intervertebral disc space next inferior to it were measured on lateral radiographs as the anterior angles of the diagonals of the respective body or disc space. In measuring the vertebral body height, the interobserver error (SD) was 3.2 and the intraobserver, 2.6 degrees, and in measuring the intervertebral disc space height, the interobserver error was 2.4 and the intraobserver, 1.8 degrees. The angles can be transformed to a corresponding height/length ratio by a simple trigonometrical formula.

Cobb angle versus spinous process angle in adolescent idiopathic scoliosis. The relationship of the anterior and posterior deformities

Abstract: The standard clinical measurement for adolescent idiopathic scoliosis is the Cobb angle, measured from the end-plates of the end vertebral bodies in a standing radiograph. This measurement of anterior column structures describes the anterior spinal deformity. The posterior spinal deformity can be described by the "spinous process angle," measured from a curve joining the tips of the spinous processes. A computer model, and a radiographic study of Cobb angle, spinous process angle and vertebral rotation show that adolescent idiopathic scoliosis results in larger angulations of the anterior elements than posterior elements. This helps to explain some of the inherent limitations of posterior instrumentation, including Cotrel-Dubousset instrumentation, and of noninvasive posterior surface measurement systems.

Curve progression after treatment with the Wilmington brace for idiopathic scoliosis.

Abstract: We evaluated curve progression after completion of Wilmington brace treatment for adolescent idiopathic scoliosis in 67 patients. Follow-up ranged from 5 to 13 years. Pretreatment curve magnitudes ranged from 20 to 39 degrees, with a Risser sign of 0 or 1. Sixteen patients (21%) experienced 5-16 degrees of curve progression after brace treatment was discontinued. For nine of these patients, the final curve magnitude was within 5 degrees of the pretreatment Cobb angle, reflecting a loss of correction achieved during brace treatment. The remaining seven patients had final curve magnitudes measuring 8-32 degrees greater than the pretreatment Cobb angle.

End vertebra angle--a roentgenographic method to describe a scoliosis. A follow-up study of idiopathic scoliosis treated with the Boston brace.

Abstract: A new method of measuring the range of the lateral deviation of a scoliosis is introduced. Here the Cobb angle is divided into two separate parts, consisting of the angles between each end vertebra and the horizontal plane. This angle is called the end vertebra angle. One hundred and twenty-one patients with adolescent idiopathic scoliosis, treated with Boston braces, were measured according to this technique and these angles were compared with the Cobb angles. All patients had S-shaped, right convex thoracic and left convex lumbar scolioses. Three end vertebra angles were measured and called A, B, and C. The middle end vertebra angle (B) was responsible for the improvement of the scoliosis in the brace, measured according to Cobb, and also the remaining improvement 2 years after weaning from the brace. The proximal and distal end vertebra angles (A and C), however, were unchanged or had increased at the time of the follow-up study 2 years after weaning from the brace treatment when compared with the status before the treatment. This could not be observed by using the Cobb method only. If end vertebra angles A and B are not equal, the thoracic curve is asymmetric. This asymmetry can be of two types depending on which of the two end vertebra angles is the greater one. If A is greater than B, the result of brace treatment was more successful than that of the symmetric curves.(ABSTRACT TRUNCATED AT 250 WORDS)

An analysis of the effect of the Zielke operation on S-shaped curves in idiopathic scoliosis. A follow-up study revealing some skeletal and soft tissue factors involved in curve progression.

Abstract: This article analyzes the fate of S-shaped idiopathic spinal curves during follow-up in 18 patients having the Zielke VDS operation. The spinal radiographs were evaluated by Cobb angle, end-vertebra angles (EVAs), vertebral rotation, and by a new method using the tilt of the surgically fused spinal block in the frontal plane. Spinal growth was measured. Using the conventional criterion for Cobb angle progression, 83% of the lower curves and 50% of the upper curves progress. The use of EVAs shows that progression occurs mainly in the middle (thoracolumbar) segment of the spine. Curve progression occurs in the frontal plane without any significant change in vertebral rotation. The progression of the upper curve Cobb angle is not related to the progression of the Cobb angle of the lower curve; but it is related to 1) tilt of the spinal block, 2) growth of the spine below the block and 3) overall linear spinal growth (T1-S1). Progression of the upper EVA of the upper curve is associated with skeletal immaturity. The key features leading to curve progression after the Zielke operation appear to be spinal asymmetry in the frontal plane, linear spinal growth, and concave lumbar muscle tether (myostatic contracture). The surgical implications of the findings are outlined.

Studies of experimental scoliosis produced by electrical stimulation. With special reference to the histochemical properties of the muscle

Abstract: 1) Back muscles on the right side of the rat were daily stimulated with electrical pulses through implanted electrodes. As a result, a scoliosis with convexity toward the non-stimulated side was produced. The cobb angle increased with time and became 18.6 +/- 9.9 degrees on average after 3 weeks. 2) On the stimulated side, type I fibers showed a significant increase in diameter. The area they occupied in the cross section, as well as the ratio of the area against that of type II fibers, were increased. These increases disappeared 3 weeks after the termination of the stimulation, whereas the scoliosis remained almost the same, maintaining an average angle of 17.2 +/- 7.4 degrees after 3 weeks. 3) From these results, the possibility was suggested that electrical stimulation is of use in treating idiopathic scoliosis.

Experiences with lateral electric surface stimulation in the treatment of idiopathic scoliosis

Abstract: Lateral electrical surface stimulation (LESS) was used for treatment of idiopathic scoliosis in 20 children and adolescents (mean age 10.9 years, mean Cobb angle 26 drs.). Six patients were treated until skeletal maturity showing a mean curve progression of 8 degrees at follow-up. In 14 patients treatment failed due to skin irritation, sleeping disturbances or progression. Five patients had to be operated on. Twenty patients of a control group treated with Boston brace (mean age 11.9 years, mean Cobb angle 34 drs.) showed mean curve improvement of 2 degrees at follow-up. Only one patient of the control group had to be operated on. Brace treatment was superior to stimulation in this small patient group presented.

Indications for early surgery in cases of lumbar and dorsolumbar scoliosis: the role of vertebral rotation.

Abstract: There are very few objective criteria for the choice between conservative and surgical treatment of lumbar and dorsolumbar scoliosis ranging from 40 to 50 degrees. We reviewed the long-term results obtained in 76 patients treated with plaster braces because they had refused surgical treatment; in 56% of the cases a nearly 10 degree gain was maintained after the onset of treatment; all of the cases which showed improvement presented a reduction in the curve by at least half and rotation by at least one-third in tests in suspension or in bending, and this was maintained in plaster. In cases where the long-term results were poor, however, rotation did not change. In conclusion, of the many parameters examined, only a combined assessment of the reducibility of both the Cobb angle and of rotation provides a valid indication for the treatment of lumbar and dorsolumbar curves ranging from 40 to 50 degrees.

Screening for Scoliosis: A Review of the Evidence

Abstract: This review of the literature from 1977 forward is addressed particularly to benefits of screening for adolescent idiopathic scoliosis The literature yielded little experimental or quasi-experimental evidence Therefore, the chapter is based mainly on descriptive studies