Showing papers on "Cobb angle published in 1996"

Use of the Milwaukee Brace for Progressive Idiopathic Scoliosis

Abstract: One hundred and two (92 per cent) of 111 immature patients in whom idiopathic scoliosis had been treated with a Milwaukee brace were followed to determine the effectiveness of the brace in preventing progression of the scoliosis. The average time from cessation of bracing until the latest radiographs were made for the patients who were managed non-operatively was six years and four months. The average progression of the curve, from the time of initial bracing until use of the brace was stopped, in the eighty-eight patients who were included in the statistical analysis was 4 degrees. The curve continued to progress an average of 5 degrees after use of the brace was stopped in the patients who did not have an arthrodesis. Forty-two patients (48 per cent) had more than 5 degrees of progression at the time that use of the brace was stopped. Thirty-seven patients (42 per cent) had an operation or a curve of sufficient magnitude to warrant operative intervention. The maximum correction of the Cobb angle in the brace had prognostic importance for progression of the curve. The patients in whom the curve did not progress or who did not need operative intervention had had an average correction of 20 per cent, while the patients who had a failure had had an average correction of 8 per cent. The patients who eventually had the indications for an arthrodesis were, on the average, one year younger (eleven years and nine months) and had a curve of a larger magnitude at the time of bracing than the patients who did not need an arthrodesis. The findings of this study do not agree with previously reported favorable results with bracing and raise questions about whether the natural history of progressive idiopathic scoliosis is truly altered by use of the Milwaukee brace.

Prediction of scoliotic cobb angle with the use of the scoliometer

Abstract: Study design A prospective study was conducted in a young homogenous adolescent population, with the use of the scoliometer. Objectives To create a mathematic formula that provides the accurate Cobb angle of idiopathic scoliosis with the use of the scoliometer only. Summary of background data The scoliometer is an accepted method for detection and evaluation of scoliosis during screening programs. To the author's knowledge, there are no previous methods and formulas to estimate the approximate Cobb angle using only the scoliometer. Methods Several clinical (scoliometer value, age, and sex) and radiographic (Cobb angle, Perdriolle of and apical vertebra, Risser iliac apophysis classification) parameters from 442 (4.37%) of 10,109 screened adolescents who had a scoliometer value of at least 7 degrees were taken and correlated using the simple and multiple linear regression analysis. Results Cobb angle and scoliometer value were statistically significantly correlated to each other. Two mathematic formulas were created to predict the Cobb angle of the thoracic and lumbar scoliosis, with similar sensitivity and accuracy. The thoracic and lumbar scoliometer values were statistic significantly correlated with the thoracic and lumbar Cobb angle (P = 0.0254 and P = 0.0015, respectively). The lumbar scoliometer value was significantly correlated with lumbar apical vertebra Perdriolle value. Also, the thoracic and lumbar Cobb angles were significantly correlated with thoracic and lumbar apical vertebra (P = 0.0001 and P = 0.0015, respectively). Conclusions In the present study, the authors have constructed two mathematic formulas, which provide accurately the scoliotic Cobb angle in young adolescents using only the scoliometer with a deviation of 5.63 degrees thoracic curves and 5.79 degrees for lumbar curves. The authors recommended that all physicians engaged in scoliosis screening programs use the scoliometer based on the mathematic formulas that the authors developed. They believe that this method will reduce the cost of school screening programs, the overdiagnosis, and the unnecessary exposure to irradiation of this young population in the future.

Late-onset idiopathic scoliosis in children six to fourteen years old. A cross-sectional prevalence study.

Abstract: We performed a point-prevalence survey of 15,799 children, six to fourteen years old, who formed part of a prospective longitudinal study. Our purpose was to detect the prevalence of scoliosis and to investigate associated factors. On the basis of the initial screening, 934 children (5.9 per cent) were referred for additional clinical and radiographic examinations; 896 children returned for this second evaluation. A lateral spinal curve with a Cobb angle of more than 5 degrees was seen in 431 children (2.7 per cent of the 15,799 children). Only seventy-six children (0.5 per cent) had a curve that met our definition of idiopathic scoliosis (a curve of more than 10 degrees with concordant apical rotation). The point-prevalence rate was higher in girls, and it increased with age. The rate was 0.1 per cent (four of 5246) in the age-group of six to eight years, 0.3 per cent (sixteen of 5831) in the age-group of nine to eleven years, and 1.2 per cent (fifty-six of 4722) in the age-group of twelve to fourteen years old. With allowance for the fact that different definitions of idiopathic scoliosis have been used in earlier studies, our results suggest that the natural history of idiopathic scoliosis may be becoming more benign spontaneously.

Measurement of vertebral rotation in idiopathic scoliosis using the Perdriolle torsionmeter: a clinical study on intraobserver and interobserver error

Abstract: This study was designed to determine the reliability and accuracy of the Perdriolle torsionmeter. Fifty-four observers were divided into three groups according to their previous experience in the field of orthopaedics and the treatment of scoliosis. Each observer, on two separate occasions, measured the apical vertebral rotation on preoperative and postoperative roentgenograms of three idiopathic thoracic scoliotic curves using the torsionmeter. For all groups, there was no statistically significant difference (P>0.05) between the average of the first and the average of the second measurements of vertebral rotation of any of the curves. In the curve with the highest frontal Cobb angle and vertebral rotation of more than 30°, there was a statistically significant difference (P=0.03) between the average measurements of the three groups of observers. We concluded that, as both intraobserver and interobserver error risks were insignificant, the torsionmeter can be accurately used by everyone in the fields of orthopaedics provided the vertebral rotation is not greater than 30° and the curve is mild or moderate. The reliability and accuracy of the torsionmeter was found to be questionable at more than 30° of vertebral rotation because of increased risk of interobserver error.

Pulmonary function before and after anterior spinal surgery in adult idiopathic scoliosis.

Abstract: BACKGROUND: Little is known about the long term effects of anterior spinal surgery on pulmonary function in adult patients with idiopathic scoliosis. A study was therefore undertaken of pulmonary function before and after anterior spinal surgery in this group of patients. METHODS: Fourteen patients (12 women) of mean age 26.5 years (range 17-50, 10 > or = 20 years) were studied. All 14 patients underwent thoracotomy and anterior arthrodesis, and five also underwent posterior arthrodesis. Scoliosis curves and lung volumes were measured preoperatively and at a mean follow up of 32 months (range 14-49) after surgery. RESULTS: At long term follow up after surgery the mean (SD) Cobb angle of the thoracic curve improved from 59 degrees (25 degrees) to 39 degrees (18 degrees), a correction of 31%. Despite this there was a fall in mean forced vital capacity (FVC) of 0.21 litres (95% confidence interval 0.04 to 0.38). In the patients who underwent anterior surgery without posterior surgery (n = 9) there was a fall in mean FVC of 0.31 litres (95% confidence interval 0.12 to 0.50); mean forced expiratory volume in one second and total lung capacity were also reduced and there was an increase in mean residual volume. CONCLUSIONS: Forced vital capacity is reduced at long term follow up in adult patients with idiopathic scoliosis who undergo anterior spinal surgery. The fall in FVC is small and is unlikely to be of clinical significance in patients with reasonable lung function in whom surgery is planned for prevention of curve progression or improvement of cosmetic appearance and pain. However, surgical intervention should not be undertaken in an attempt to improve pulmonary function.

Surgical correction of vertebral axial rotation in adolescent idiopathic scoliosis: Prediction by lateral bending films

Abstract: The pre- and postoperative radiographs of 45 patients with scoliosis were compared with the preoperative lateral bending radiographs. The purpose was to compare correction of Cobb angle and apical vertebral rotation between preoperative lateral bending and operative spinal instrumentation. Twenty-one patients had Harrington instrumentation, 12 had Drummond/Wisconsin spinous process segmental instrumentation, and 12 had Texas Scottish Rite Hospital instrumentation. From the pre- and postoperative radiographs, each vertebra was marked and digitized for computerized measurements of Cobb angle and apical vertebral rotation. Correction of Cobb angle on the lateral bending radiograph averaged 22 +/- 10 degrees, which was less than that achieved at operation (Harrington 23 +/- 7 degrees, Drummond/Wisconsin 29 +/- 10 degrees, and Texas Scottish Rite Hospital 36 +/- 6 degrees; p < 0.01, paired t test). In contrast, correction of apical vertebral rotation on the lateral bending radiograph averaged 4 +/- 8 degrees, which was not significantly different from that achieved at operation (Harrington 1 +/- 8 degrees, Drummond/Wisconsin 1 +/- 7 degrees, and Texas Scottish Rite Hospital 4 +/- 8 degrees). Spinal instrumentation markedly corrected the Cobb angle but minimally corrected apical vertebral rotation. In contrast, preoperative lateral bending produced a similar proportional correction of both.

Convex spinal epiphysiodesis in the management of progressive infantile idiopathic scoliosis.

Abstract: Study Design. Retrospective review of patient records with current clinical and radiographic assessment. Objective. To evaluate the long-term result of anterior and posterior convex psinal growth arrest, with or without instrumentation, in managing infantile idiopathic scoliosis. Summary of Background Data. There were 12 male and 10 female patients studied, with a mean follow-up period of 10 years, 9 months. The mean Cobb angle before surgery was 65°. All had a rib vertebral angle difference more than 20°. The mean age at surgery was 6 years. Nine patients had epiphysiodesis alone; nine patients also underwent Harrington instrumentation simultaneously, and four underwent Harrington instrumentation 2-4 years later. Method. Clinical evaluation and sequential measurements of Cobb angle were done. Results. The epiphysiodesis-only group had a mean preoperative Cobb angle of 72°, mean progression of curves of +12°, and mean rate of progression of +2.5° per year; the group's postoperative figures were 92°, +15°, adn +3° per year, respectively. The epiphysiodesis and late Harrington rod group had a mean preoperative Cobb angle of 56°, mean progression of +12°, and a mean rate of progression of +5° per year; the group's postoperative Cobb angle averaged 62°, progression +6°, and rate of progression +1° per year. The epiphysiodesis with simultaneous Harrington rod group had a properative mean Cobb angle of 60°, mean progression of +18°, and mean rate of progression of +6° per year. After surgery, these improved to 58°, correction of 2°, and rate of correction of 0.5° per year. Conclusion. Combined anterior and posterior convex spinal growth arrest alone does not prevent progression of deformity in infantile idiopathic scoliosis. The addition of posterior instrumentation can slow or arrest deformity progression but not reverse it.

A comparison of radiographic and electrogoniometric angles in adolescent idiopathic scoliosis.

Abstract: STUDY DESIGN: This was a cross-sectional study of a consecutive group of adolescent patients presenting to a scoliosis clinic for routine assessment or monitoring of their scoliosis, excluding postsurgical patients. SUMMARY OF BACKGROUND DATA: In vitro studies suggested electrogoniometry could be useful in the evaluation of scoliosis. No prior in vitro study had been performed. OBJECTIVES: To determine the reliability and validity of an electrogoniometric instrument, the Metrecom Skeletal Analysis System, in assessing adolescent idiopathic scoliosis. METHODS: Thirty-one patients were examined, radiographed, and scanned with the Metrecom Skeletal Analysis System twice by two different examiners. The magnitudes of the curves derived from the Metrecom Skeletal Analysis System scans were compared with each other and with the Cobb angles measured from standing radiographs. RESULTS: The intraclass correlation coefficient (a measure of agreement, ranging from 0 to 1, where 1 represents complete agreement) for the intraexaminer reliability of the Metrecom Skeletal Analysis System ranged from 0.71 to 0.83. The interexaminer reliability intraclass correlation coefficient of the Metrecom Skeletal Analysis System was 0.58, with a mean difference between examiners of 5.5 degrees (SD = 5 degrees), and limits of agreement (mean difference +/-2 SD) ranging from -4.5 degrees to 15.6 degrees. The Metrecom Skeletal Analysis System and the radiographically derived Cobb angle correlation was 0.64, but the mean difference between the methods was 3.7 degrees (SD = 11.1), with limits of agreement from 18.4 degrees to 25.9 degrees. CONCLUSION: The Metrecom Skeletal Analysis System does not provide sufficient clinical precision to substitute for the Cobb angle measured from spinal radiographic measurements in the management of adolescents with scoliosis.

The position of the aorta in relation to the vertebra in patients with idiopathic thoracic scoliosis.

Abstract: One CT-scan at the central part of the vertebral body of the apical vertebra of 32 patients with right convex thoracic idiopathic scoliosis and one CT-scan of either T8 or T9 of 22 normal subjects are included in this study. The position of the aorta in relation to the apical vertebra of the scoliotic patients and the corresponding vertebra of the normal subjects was determined at the horizontal plane. The mean lateral translation of the aorta in relation to the mid axis of the vertebral body increased from 19.7±4.3 mm in the normal group to 26.4±4.1 mm in the scoliotic group (p = 0.0001). In the normal group the aorta was located 41.7±8.6 mm in front of a perpendicular line to the mid axis of the vertebral body and in the scoliotic group this distance was reduced to 30.0±9.0 mm making the position of the aorta more posterior in the scoliotic group (p = 0.0001). This was in accordance with a decreased mean kyphosis-lordosis index from 0.53 ± 0.06 in the normal group to 0.46±0.07 in the scoliotic group (p−0.01). The position of the aorta, also expressed as the angle formed between the aorta and the vertebral body, the “aorto-vertebral angle”, was increased from 24.4°±6.9° in the normal group to 41.4°±8.4° aorto-vertebral angle did not change significantly with increasing Cobb angle (p = 0.26) but was positively correlated to the vertebral rotation (p = 0.0001). An estimation of the length of the intercostal arteries revealed a significantly greater R (right)/L (left) index in the scoliotic patients 1.18±0.11 than in the normal subjects 1.08±0.06 (p−0.0003). It is concluded that the rotation and the anterior displacement of the vertebral body in scoliosis result in a deviation of the aorta along the left (concave) side of the vertebral body to a more posterior position relative to the vertebral body with a possible increased length of the intercostal artery on the right (convex) side.

Adolescent idiopathic scoliosis: an update.

Abstract: Adolescent idiopathic scoliosis is defined as a lateral spinal curvature of greater than 10 degrees, for which no pathologic cause can be determined. The initial assessment of adolescents with scoliosis focuses on identification of any treatable underlying pathology. Adolescents with scoliosis typically are asymptomatic and have normal neurologic and physical examinations, with the exception of curvature of the spine. Treatment strategies are determined by the risk of progression. This risk depends on the extent of the curvature and anticipated future spinal growth. The extent of the curvature may be estimated by use of a scoliometer and verified by calculation of the Cobb angle on radiographic evaluation. Skeletal maturity may be estimated by several methods, including radiologic estimates of ossification by bone atlas or Risser sign. Treatment strategies include bracing and surgery.

The segmental effect of Cotrel-Dubousset instrumentation on vertebral rotation, rib hump and the thoracic cage in idiopathic scoliosis

Abstract: The segmental effect of Cotrel-Dubousset instrumentation (CDI) on the spine and thoracic cage was investigated in 38 patients with adolescent idiopathic scoliosis by preoperative and postoperative postero-anterior and lateral radiographs and computed tomography from T1 to S1. Mean Cobb angle decreased by 67%. The T5-T12 kyphosis in the hypokyphotic patients increased on average by 8.4 degrees (P < 0.001). Average preoperative as well as postoperative maximal vertebral rotation was located at the apex level, and was reduced from 19.0 degrees to 14.3 degrees (P < 0.001). All vertebrae between the upper and lower instrumented vertebrae were significantly derotated. Average derotation for the apical zone was 4.8 degrees (P < 0.001), for the upper instrumented zone it was 2.5 degrees (P < 0.01), and for the lower instrumented zone it was 2.6 degrees (P < 0.01). Vertebral derotation was significantly higher in the apical zone than in the upper and lower instrumented zones. The apical rib hump index (RHi) decreased by 38% (P < 0.001) and the cumulative RHi for the five apical levels decreased by 34% (P < 0.001). The RHi for the two levels above and below the instrumentation each decreased by 20% (n.s.). No significant increase in sagittal or transverse rib cage diameter at any level was observed. The translation in the coronal plane of the apical vertebra of major right thoracic curves improved significantly (P < 0.001). The preoperative flexibility index of the major curve correlated positively (r = 0.47) with derotation at the apex level (P < 0.01). However, no correlation was found between flexibility index and reduction of RHi at the apex level. Vertebral derotation did not correlate with reduction in RHi at any level. The study shows that CDI results in a postoperative three-dimensional improvement of the spine and a limited improvement of the thoracic cage, with no tendency towards a worsened deformity at any level within or outside the instrumentation.

Threshold values for supine and standing Cobb angles and rib hump measurements: prognostic factors for scoliosis

Abstract: Seven parameters recorded at the first clinical examination of 326 growing scoliotic patients were correlated with the speed of progression of the scoliotic curve during a natural history survey period. The parameters were: age; bone age (according to Greulich and Pyle); pubertal and Risser stage; curve shape; rib hump, measured in forward bending in a sitting patient and supine and standing radiographic Cobb angles of the scoliotic curve. The speed of progression of the scoliotic curve was expressed as the annual increase in Cobb angle. It was quantified graphically after plotting the measurements taken from all the radiographic examinations made during the survey. The survey period ranged from 6 months to several years, depending on the rate of progression. It was 6 months only if the scoliotic curve demonstrated worsening of more than 3° at two successive examinations performed at least 3 months apart. The authors aimed to identify the minimum values of curve angle and rib hump, identified at first examination in 95–100% of patients whose parameters at follow-up were above these values (supine angle: 17°; standing angle: 24°; rib hump: 11 mm), therefore demonstrating curve worsening. Then, they analysed how the other parameters such as age, bone age, state of maturation and curve shape influenced these threshold values of rib hump and supine and standing angles. The authors present the threshold values for the whole sample according to the sexual state of maturation and also for each curve shape. They demonstrate that a combination of states of maturation, several measures of the scoliotic curve and curve shape provides the best basis for individual prognosis.

Geometric analysis of coronal decompensation in idiopathic scoliosis.

Abstract: Study Design. Frontal plane geometry of postoperative curves was analyzed using a geometric model to investigate the relationship between coronal decompensation and postoperative apical shifts from the center sacral line for various thoracic and lumbar Cobb angles. Objectives. To determine if a balanced spinal configuration is possible when the postoperative lumbar curve is larger than the thoracic curve, and to determine the limits on the postoperative magnitude of the lumbar curve relative to the thoracic curve beyond which a spinal configuration with acceptable balance cannot be achieved. Summary of Background Data. Previous studies have suggested that overcorrection of the primary thoracic curve may be the principal cause of coronal decompensation after selective thoracic correction and fusion in King Type II curves. Also, other causative factors, such as inappropriate selection of fusion levels and hook patterns, have been implicated as possible reasons for decompensation after Cotrel-Dubousset instrumentation for idiopathic scoliosis. Methods. Postoperative thoracic curves of 20°, 25°, and 30° were simulated on a model spine. For each thoracic Cobb angle, three left lumbar curves were simulated with the lumbar curve larger than thoracic by 5°, 10°, and 15°. For each combination of thoracic and lumbar Cobb angles, spinal configurations corresponding to different lateral shifts on the thoracic and lumbar apical vertebrae from the center sacral line were obtained. Results. For a given combination of postoperative thoracic and lumbar Cobb angles, there is an optimal range of postoperative lateral distance between the thoracic and lumbar apices (relative apical distance) that will maintain acceptable balance (decompensation ≤10 mm). Smaller values of the relative apical distance will decompensate the spine. For a constant postoperative thoracic Cobb angle, the postoperative distance between the thoracic and lumbar apices needed to maintain a balanced spine increases with increasing postoperative lumbar Cobb angle. Similarly, for a constant difference between the postoperative thoracic and lumbar Cobb angle, the postoperative distance between the toracic and lumbar apices needed to maintain a balance spine increases with increasing postoperative thoracic Cobb angle. For postoperative thoracic curves of 20°-30°, acceptable balance can be achieved when the magnitude of the postoperative lumbar curve is up to twice the thoracic curve as long as adequate postoperative relative apical distance can be maintained. Conclusions. Decompensation does not appear to be caused by the relative magnitudes of the postoperative thoracic and lumbar curves, but is a result of inadequate relative distance between the thoracic and lumbar apical vertebrae in the postoperative geometry.

A Mathematical Expression of Three-Dimensional Configuration of the Scoliotic Spine

Abstract: Three-dimensional configuration of the scoliotic spine was mathematically expressed by a spatial curve passing through each vertebral centroid ("vertebral body line"). Three-dimensional location of the vertebral centroid was determined from digitization on the frontal and sagittal roentgenograms. Cobb angle, which is clinically used for measuring scoliosis curvature, was calculated in space to evaluate scoliosis deformity three-dimensionally. In forty-five scoliotic spines, regardless of curvature and curve patterns, the spinal configurations were excellently approximated by vertebral body lines. Vertebral body lines swerved from the sagittal plane at the end vertebrae, but aligned on a certain plane within the scoliosis region. Three-dimensional Cobb angle, which was larger than that in the frontal plane, can be utilized to evaluate the scoliosis deformity.

A new method using top views of the spine to predict the progression of curves in idiopathic scoliosis during growth.

Abstract: Study Design. A prospective longitudinal study of 51 patients with idiopathic scoliosis using spinal stereoradiographs was performed. The top view, which was obtained from stereoscopic anteroposterior and lateral radiographs, was analyzed for predicting the progression of spinal deformity. Objectives. To show that the top view facilitates prediction of curve progression in idiopathic scoliosis at the initial examination. Summary of Background Data. Four progression factors were set up using the top view and were analyzed statistically for predicting progression. No previous study has assessed this concept. Methods. Fifty-one patients with idiopathic thoracic scoliosis or combined thoracic and lumbar scoliosis were studied longitudinally. There were 24 untreated patients and 27 patients treated with braces. Four potential progression factors were evaluated using the top view : 1) the ratio of the frontal size and the sagittal size in the top view, 2) the magnitude and direction of the vector describing the plane of maximum curvature in the thoracic spine, 3) the magnitude and direction of the vector describing the plane of maximum curvature in the lumbar spine, and 4) the balance of these vectors between the thoracic and lumbar curve. All cases were classified into five groups according to these four factors. The probability of the progression was evaluated statistically, and the prevalence of curve progression was found in each group. Results. The probability of progression of a scoliosis curve increased according to the increase of these four factors. No significant difference was found between Cobb angle at the initial examination and that at skeletal maturity in untreated patients with a small risk of progression. The patients with a large risk of progression and who were treated with braces showed progression of curvature despite brace treatment. Conclusion. The present study has evaluated factors relating to progression in scoliosis using the top view. These results may help predict the risk of progression in idiopathic scoliosis.

MRI of Unfused Lumbar Segments After Spondylodesis.

Abstract: PURPOSE Our goal was to find a causal relation between disk degeneration in nonfused lumbar segments, back pain, and the angle of scoliotic curves 21-30 years after dorsal spondylodesis. METHOD Thirty-two patients with scoliosis had been treated by dorsal spondylodesis 21-30 years prior to this study (mean 25.2 +/- 2.4 years). With use of MRI, signs of disk degeneration in the nonfused lumbar segments (n = 131, mean 4.1 +/- 1.4) were evaluated. Back pain evaluation was performed using the Oswestry disability score. On plain X-ray films, the angle of scoliotic curves was measured (Cobb technique). Percentage and absolute number of degenerated disks were compared to the fusion level (number of unfused caudal segments), the Oswestry score, and the Cobb angle. RESULTS Disk degeneration was present in 20 of 32 patients (62.5%) and in 37 of 131 unfused lumbar segments (28.2%). Of eight patients (24.2%), seven had moderate back pain and one severe back pain. The mean lumbar scoliotic curve was 44.4 +/- 24.9 degrees. No statistically significant correlation was found between patients with disk degeneration and fusion level, amount of back pain, or lumbar scoliotic angle (p < 0.05). CONCLUSION A lack of correlation between disk degeneration in unfused lumbar segments and other parameters like fusion level, back pain, and scoliotic angle can be assessed in the long-term follow-up of multisegment fusion of scoliotic curves.

Morphological Modeling and Growth Simulation of Idiopathic Scoliosis

Abstract: Scoliosis is defined as an appreciable lateral deviation with axial rotation in the normally straight vertical line of the spine Idiopathic scoliosis is a deformity that develops during a period of rapid growth and is reduced after skeletal maturity As a biomechanical approach to scoliosis, this chapter presents both a morphological modeling method to mathematically express the three-dimensional configuration of the scoliotic spine and a computer simulation method to examine the effect of asymmetrical local growth on scoliosis deformities of the spinal column In morphological modeling, the three-dimensional location of the vertebral centroid was reconstructed from both fronal and sagittal roentgenograms The Cobb angle, which is an important clinical index used for the evaluation of scoliosis curvature, could be calculated numerically and three-dimensionally from the proposed model The other geometrical characteristics of the spatial curve of the scoliotic spine were also confirmed In simulation of growth deformation, a three-dimensional, finite-element model of the normal skeletal spine was constructed It consists of the vertebrae and the intervertebral disks of the thoracolumbar region from T-1 to L-5, the sacrum, the rib pairs 1-10, the sternum and costal cartilages, and the joint capsules Bony growth deformation induced by growth force was defined as permanent deformation When the axial asymmetrical growth force was applied to the lateral region from the left to posterior in the T-8 vertebral body, this model could simulate well a single scoliosis curvature toward the lateral direction with vertebral rotation, as seen in typical scoliosis deformities