Showing papers on "Cobb angle published in 1998"

Pelvic incidence: a fundamental pelvic parameter for three-dimensional regulation of spinal sagittal curves

Abstract: This paper proposes an anatomical parameter, the pelvic incidence, as the key factor for managing the spinal balance. Pelvic and spinal sagittal parameters were investigated for normal and scoliotic adult subjects. The relation between pelvic orientation, and spinal sagittal balance was examined by statistical analysis. A close relationship was observed, for both normal and scoliotic subjects, between the anatomical parameter of pelvic incidence and the sacral slope, which strongly determines lumbar lordosis. Taking into account the Cobb angle and the apical vertebral rotation confers a three-dimensional aspect to this chain of relations between pelvis and spine. A predictive equation of lordosis is postulated. The pelvic incidence appears to be the main axis of the sagittal balance of the spine. It controls spinal curves in accordance with the adaptability of the other parameters.

A comparison of manual versus computer-assisted radiographic measurement. Intraobserver measurement variability for Cobb angles.

Abstract: Study Design. A comparison between computer-assisted measurement using digitized radiographs, which has the potential to reduce error, and manual measurement using standard radiographs. Objective. To assess measurement variability for the Cobb method on digital radiographs and compare it with that of manual measurements on standard radiographs. Background Data. Studies of the Cobb method have demonstrated multiple sources of error leading to significant intraobserver measurement variability. Estimates for the 95% confidence interval for intraobserver variability range from 2.8 degrees to 10 degrees. Methods. Twenty-four scoliosis radiographs were measured by six examiners. Two measurement sets were done manually ("manual set"), and two measurement sets were done on digitized images using a computer mouse ("computer set"). Results. For the manual set, the 95% confidence interval for intraobserver variability was 3.3 degrees (range, 2.5-4.5 degrees). For the computer set, the value was 2.6 degrees (range, 2.3-3.3 degrees). This difference in 95% confidence intervals between the manual and computer sets was statistically significant (P Conclusions. The results of this study demonstrate that intraobserver variability for manual and computer Cobb angle measurements yield a 95% confidence interval of approximately 3 degrees, with the computer having a slightly lower variability. The computer technique removes sources of intrinsic error, e.g., the variability introduced by using different manual protractors, the inaccuracy of standard protractors, and the use of wide-diameter radiographic markers. Identical digital images can be shared electronically between centers, without having to duplicate and mail films. Multicenter studies in which different examiners will be measuring Cobb angles may consider using the computer as a measuring device to reduce intrinsic measurement errors.

Elliptical modeling of the sagittal lumbar lordosis and segmental rotation angles as a method to discriminate between normal and low back pain subjects

Abstract: Clinical significance of lumbar lordosis has not been agreed on. Our purpose is to compare lordotic measurements of normal and pain subjects and to test the validity of a new anthropometric model of lumbar curvatures. Digitized radiographic points (body corners) from standing lateral lumbar radiographs were modeled with ellipses in a least-squares method and were used to create segmental angles, a global angle at L1-L5, a Cobb angle from T12 to S1, Ferguson's sacral base angle, and an angle of pelvic tilt. Fifty normal subjects were matched in age, sex, weight, and height with 50 acute pain subjects, 50 chronic pain subjects, and 24 pain subjects with radiographic abnormalities. Of 11 angles, 2 distances, and 2 ratios, statistical analysis was significantly different across groups for 12 of these measurements, with the alternative hypotheses accepted for the other 3 measurements. The lordosis of both normal and low back pain subjects can be successfully modeled with a portion (approximately 86 degrees) of an ellipse, but with different major and minor axis ratios. The normal group's average elliptic lordosis has the smallest least-squares error, approximately 1 mm per digitized point, with (minor axis)/(major axis) ratio = 0.39, L1-L5 global angle = 40 degrees, and Cobb angle = 65 degrees. The chronic and radiographic abnormalities pain groups have an elongated ellipse with hypolordosis, reduced L1-L5 global angle = 29.6-35 degrees, reduced Cobb angle = 57-58 degrees, and elliptic axis ratio = 0.27-0.30. The acute pain group is hyperlordotic with the largest L1-L5 global angle, largest Cobb angle = 70 degrees, largest Ferguson's angle, and largest pelvic tilt angle.

Osteoid osteoma and osteoblastoma of the spine. Factors associated with the presence of scoliosis.

Abstract: STUDY DESIGN A retrospective study of 44 museum cases of spinal osteoid osteoma or osteoblastoma and a meta-analysis using 421 additional cases from a review of the literature. OBJECTIVES To identify the factors that are associated with the development of scoliosis in these patients. SUMMARY OF BACKGROUND DATA Painful scoliosis is a well recognized presentation of spinal osteoid osteoma and osteoblastoma and is considered to be secondary to pain-provoked muscle spasm on the side of the lesion. Previous studies have been based on small numbers of patients that did not permit statistical validation of the reported observations. METHODS Eight factors were assessed including: age, gender, duration of symptoms, site of lesion in the spine, vertebral level of lesion, site of lesion in the individual vertebra, type of lesion, and Cobb angle at presentation. Reports were reviewed only if the presence or absence of scoliosis could be determined. Statistical analyses initially were performed on the museum cases and then on a combination of museum cases and cases from the literature. RESULTS Overall, 63% of subjects had scoliosis. The lesions were typically present on the concave aspect of the curve. Three cases of scoliosis from the literature involved lesions that were reported to be on the convexity. Scoliosis is significantly more common in cases of osteoid osteoma than in cases of osteoblastoma (P < 0.0001); lesions are more common in the thoracic and lumbar regions than in the cervical region (P < 0.0001), in lower cervical region than in the upper cervical region (P value = 0.0027), and they are more commonly located to one side of the midline (P < 0.0001). Age, gender, and duration of symptoms were of no significance. CONCLUSIONS The findings support the concept that scoliosis is secondary to asymmetric muscle spasm in patients with spinal osteoid osteoma or osteoblastoma.

Idiopathic scoliosis in twins studied by DNA fingerprinting

Abstract: We investigated 21 pairs of twins for zygosity and idiopathic scoliosis. DNA fingerprinting confirmed that 13 pairs were monozygotic and eight were dizygotic. There was concordance for idiopathic scoliosis in 92.3% of monozygotic and 62.5% of dizygotic twins. Of the 12 pairs of monozygotic twins concordant for idiopathic scoliosis, six showed discordant curve patterns but eight had differences in Cobb angle of less than 10°. Seven of the ten pairs of monozygotic twins had similar back shapes. Our findings suggest that there is a genetic factor in the aetiology of idiopathic scoliosis; they also indicate that there is a genetic factor in both the severity of the curve and the general shape of the back.

Idiopathic scoliosis in twins studied by DNA fingerprinting: THE INCIDENCE AND TYPE OF SCOLIOSIS

Abstract: We investigated 21 pairs of twins for zygosity and idiopathic scoliosis. DNA fingerprinting confirmed that 13 pairs were monozygotic and eight were dizygotic. There was concordance for idiopathic scoliosis in 92.3% of monozygotic and 62.5% of dizygotic twins. Of the 12 pairs of monozygotic twins concordant for idiopathic scoliosis, six showed discordant curve patterns but eight had differences in Cobb angle of less than 10 degrees. Seven of the ten pairs of monozygotic twins had similar back shapes. Our findings suggest that there is a genetic factor in the aetiology of idiopathic scoliosis; they also indicate that there is a genetic factor in both the severity of the curve and the general shape of the back.

Quantification of cosmesis for patients affected by adolescent idiopathic scoliosis.

Abstract: The aim of this study was to quantify cosmesis for patients affected by adolescent idiopathic scoliosis. Eight nonmedical judges were asked to examine photographs of 40 patients with adolescent idiopathic scoliosis, and to score the cosmesis of their backs without any information. Various parameters were measured from radiographs, Moire topographies, and physical measurements of patients, and these were compared with the cosmetic scores of the judges. The judges’ scoring proved to be reliable. The cosmetic scores showed a significant correlation with the Cobb angle, hump severity, asymmetry of the waist line, circumference of the chest, and obesity. Multivariate analysis produced equations to calculate the cosmetic score for the back. This equation is thought to have a useful clinical application.

Surgical treatment of scoliosis associated with myelomeningocele.

Abstract: Twenty-nine patients (mean age 12 years) with severe thoracolumbar and lumbar scoliosis due to myelomeningocele were treated by spinal fusion (7 by posterior arthrodesis with instrumentation, 3 by anterior arthrodesis with instrumentation, 19 by combined anterior and posterior fusion with instrumentation). Fusion was extended to the sacrum in 15 patients. Mean period of follow-up was 6.2 years. The average Cobb angle changes were as follows: thoracic and thoracolumbar curves preoperatively 86 degrees to 45 degrees at follow-up (the final average curve correction was 47%); lumbar curves preoperatively 97 degrees to 48 degrees at follow-up (the final average curve correction was 50%). Average pelvis obliquity changed from 26 degrees to 13 degrees at follow-up with an average correction of 49%. The combined anterior and posterior instrumentation and fusion gave the best correction of deformity (the final average thoracic and thoracolumbar curve correction was 55%; the final average lumbar curve correction was 61%). Independent of the method of stabilization, post-operative wound infection was a serious problem (24%). The combined fusion-instrumentation method reduced the rate of pseudoarthrosis to 14%.

Significance of sciatic scoliotic list in operated patients with lumbar disc herniation.

Abstract: Study design The authors retrospectively reviewed the relation between the location of disc herniation and pre- and postoperative changes in sciatic scoliotic list in 40 patients with surgically confirmed lumbar disc herniation who had sciatic scoliotic list with postoperative recovery. Clinical factors associated with scoliosis also were included. Objectives To evaluate the significance and pathomechanism of sciatic scoliotic list. Summary of background data The proposed causes of lumbar sciatic scoliosis mainly imply an alleviation of nerve root irritation in relation to the anatomic location of disc herniation relative to the nerve root. Methods The pre- and postoperative serial Cobb angle between L1 and L5 in anteroposterior lumbar radiographs in the standing position were measured. The relation between the convex side of scoliosis and clinical parameters in terms of the side of symptoms, age, gender, duration of low back pain or leg pain, the angle of a positive straight leg raising test, and the time required for recovery of sciatic scoliosis were investigated. In addition, magnetic resonance imaging also was performed in five recent cases from 40 patients. Results The average Cobb angle decreased from 10.7 degrees to 2.7 degrees within an average of 7.5 months after surgery. The preoperative Cobb angle of patients with disc herniation medial to the nerve root was significantly higher than that just beneath or lateral to the nerve root. Thirty-two of 40 patients (80.0%) had a lumbar disc herniation at the convex side of scoliosis, irrespective of the transverse location of the herniation. The time required for scoliosis disappearance in disc herniation located lateral to the nerve root tended to be longer than that for other types of disc herniation. Magnetic resonance imaging through the paramedian planes showed enlargement of the intervertebral foramen at the convex side of scoliosis, compared with that at the concave side in five recent cases from the current study. Conclusion These results suggest that sciatic scoliotic list is not a predictive factor of the anatomic location of disc herniation; rather, it is only suggestive of the side of disc herniation. The location of disc herniation may aide in the preoperative estimation of the recovery of the scoliosis.

Effects of three-dimensional assessment on surgical correction and on hook strategies in multi-hook instrumentation for adolescent idiopathic scoliosis.

Abstract: STUDY DESIGN A prospective study using intraoperative stereophotogrammetry to analyze change during the correction of scoliosis. OBJECTIVE To examine the relation between the number of hooks used during segmental instrumentation and the amount of correction achieved. SUMMARY OF BACKGROUND DATA An intraoperative stereophotogrammetric technique was developed at our center. Vertebral translations and rotations can be measured at several stages during scoliosis surgery. METHODS Thirty-two patients with right thoracic adolescent idiopathic scoliosis were studied using our stereophotogrammetry technique during surgical correction. Correlations were determined between apical vertebral movements and the hook ratio (number of vertebrae/number of hooks used). RESULTS Mean curve Cobb angle correction was 66%. Correction occurred in all three planes but primarily along the x and y axes. Scoliotic deformity was corrected by translation of the vertebra along the y axis and rotation about the x; physiologic kyphosis was restored by translation along the x axis and rotation about the y. The plane of maximum deformity as compared with the sagittal plane of the patient corrected from 57 degrees to 25 degrees as an indication of detorsion of the scoliotic deformity. CONCLUSIONS Increasing the number of hooks per vertebral segment significantly enhances the correction of the coronal scoliotic deformity and enhances the z axis derotation, but does not significantly change the reestablishment of the kyphosis, nor does it result in significant elongation of the spine.

A physiological approach to surgical treatment of progressive early idiopathic scoliosis

Abstract: The results of previous clinical and experimental studies have provided accumulated evidence for the role of rib asymmetry in the pathogenesis of idiopathic scoliosis (IS). Moreover, it has been shown that scoliosis induced in rabbits can be corrected by elongation or growth stimulation of ribs on the side of the convexity. Taking these observations into consideration, a 7-year-old girl with right convex thoracolumbar IS was operated upon by 2-cm shortening of three concave ribs. The preoperative coronal Cobb angle was 46° and the sagittal angle was 55°. Twenty-seven months after the operation the curves were reduced to 21° and 35°, or by 54 and 36%, respectively. It is concluded that new, easy to perform and harmless interventions on the ribs may have vast implications for the overall treatment of young patients with early progressive, thoracic, IS.

A biomechanical study of new orthotic treatment approaches for the 3D correction of scoliosis

Abstract: Scoliosis is a complex deformity of the spine and rib cage often treated by the Boston brace. The goal of this research is to study the simulation of two new treatment approaches and to compare their results to the Boston brace. A personalized biomechanical model has been used to simulate the treatment on 20 scoliotic teenagers with double curvature. On the first treatment, different forces were applied at the thoracic apex level and the posterior displacement of the rib hump was locked. For the second treatment, an oblique force oriented 45 degrees with respect to the frontal plane was added at the lumbar apex. Following each simulation, geometrical and clinical measurements were calculated and compared to the initial geometry and the Boston brace treatment. Overall, the two new treatment modalities correct the thoracic Cobb angle in the frontal plane while maintaining the normal physiological curvatures in the sagittal plane, move the thoracic plane of maximum deformity towards the sagittal plane and reduce axial rotation and rib hump. In comparison, the Boston brace reduces the Cobb angles in the frontal as well as in the sagittal planes, moves the planes of maximum deformities towards the coronal plane and has no effect on axial rotation and rib hump. This biomechanical study shows force patterns that correct scoliosis more efficiently than the Boston brace. These new treatment approaches must be personalized for each patient and still require clinical evaluation.

Correction of adolescent idiopathic thoracic scoliosis with a new type of offset apical instrumentation: preliminary results.

Abstract: Twenty patients were operated on with the same method using the AO Universal Spine System. The entire apex of the curvature was instrumented on the concave side with a newly designed pedicle hook augmented by 3.2-mm endplate screw. An offset configuration of apical and end vertebrae implants was done to maximize translation. The concave rod was derotated to 120 degrees without any distraction. The convex side was instrumented in the usual fashion. Prospective analysis showed a mean Cobb angle correction of 63% for a mean preoperative angle of 54 degrees. The apical vertebral translation was corrected to 72%. There was no major complication at the last follow-up (18-30 months). This technique compares favorably with the ones using CD principles, but needs no distraction and no instrumentation in the canal (supra or infralaminar hook).

[Idiopathic scoliosis: epidemiology and etiology].

Abstract: Authors present current knowledge about incidence and etiologic factors in idiopathic scoliosis (IS). Most data about incidence are based on screening examination in school children. Amount of patient with IS is related to the method of evaluation and experience of examiner. There is 1.9% to 3% cases in whole population if scoliosis is assumed as much as 10 degrees of Cobb angle (SRS). Etiology of IS is still in doubt despite of many investigations. There are many abnormalities in tissues but most of them probably secondary to this process. Etiology is multifactorial with dominance of inheritance. There are many genes responsible for occurrence of IS but genetic trait is still unknown.