Rib-vertebral Angle Research Articles

Derotational Casting for Progressive Infantile Scoliosis

Serial cast correction by using the Cotrel derotation technique is one of several potential treatments for progressive infantile scoliosis. This study reviews our early experience to identify which, if any, patients are likely to benefit from or fail this technique. We followed all patients treated at our institutions for progressive infantile scoliosis since 2003 prospectively at 1 institution and retrospectively at the other 2. Data, including etiology, Cobb angles, rib vertebral angle difference, Moe-Nash rotation, and space available for the lung, were recorded over time. Fifty-five patients with progressive infantile scoliosis had more than 1 year of follow-up from the initiation of casting. The diagnosis of progressive scoliosis was made based upon either a progressive Cobb angle or a rib vertebral angle difference of more than 20 degrees at presentation. All but 6 patients responded to cast correction. Nine patients have undergone surgery to date, 6 because of worsening and 3 by parent choice. As shown in the table, initiation of cast correction at a younger age, moderate curve size (<60 degrees), and an idiopathic diagnosis carry a better prognosis than an older age of initiation, curve >60 degrees, and a nonidiopathic diagnosis. The space available for the lung improved from 0.89 to 0.93. No patient experienced worsening of rib deformities. Serial cast correction for infantile scoliosis often results in full correction in infants with idiopathic curves less than 60 degrees if started before 20 months of age. Cast correction for older patients with larger curves or nonidiopathic diagnosis still frequently results in curve improvement along with improvement in chest and body shape. Derotational cast correction seems to play a role in the treatment of progressive infantile scoliosis with cures in young patients and reductions in curve size with a delay in surgery in older and syndromic patients. Level 4, therapeutic study.

Drooping of Apical Convex Rib-vertebral Angle in Adolescent Idiopathic Scoliosis of More Than 40 Degrees

It is a retrospective analysis on radiograms of 113 adolescent idiopathic scoliosis (AIS) patients with a curve of 40 degrees or more at the time of presentation. Our aim was to find out the prognostic factor for the curve progression for this group. There is general consensus in favor of operation when the curve is more than 40 degrees for AIS. There are number of reports on the prognostic and etiologic factors for the progression of scoliosis. Rib-vertebral angle (RVA) became a topic of interest regarding the progression of scoliosis for many researchers since Mehta introduced it in 1972. There were 113 AIS patients (95 females and 18 males) who had a curve of more than 40 degrees at the time of presentation, with an average age of 12 years and 10 months. We measured RVA on the convex and concave sides at the apex and 12th vertebrae and measured rib-vertebral angle difference (RVAD) using Mehta's method at each follow-up. We also measured the drooping value of the convex rib after bracing and at final follow-up. Of the 113 patients, 84 responded to bracing and in 29 the curve progressed despite bracing at final follow-up. The average drooping of rib at the apex on the convex side was 11 degrees, which progressed compared with 0.12 degrees in those who responded to treatment. On analyzing the results we could not find any relationship in 12th vertebrae but there was a significant relationship between the drooping value of convex apical rib (RVA Cx) after bracing and curve progression, which is similar to RVAD. There was no relationship between curve progression and initial angle, age, Risser sign, or menarchal status at presentation. From our study, we conclude that a large number of curves can be treated with bracing; however, when we notice drooping of the convex apical rib along with RVAD, the curve will likely progress.

Dynamic instrumentation techniques in early-onset scoliosis

Similar to the situation in idiopathic scoliosis, the decision for operative or conservative treatment is based on the progression of the curve. Apart from age and Cobb angle, the rib-vertebral angle difference and rotation of the vertebrae are decisive for the prognosis. Surgery is indicated if, despite consistent brace treatment, a progression of >10 degrees or a Cobb angle of more than 45 degrees is found. Two different dorsal dynamic systems are presently used. With the growing rod technique, one or two rods are fixed to the spine cranially and caudally and are repeatedly"lengthened." Surgery is mandatory at least every 6 months. The Orthobiom system follows a new approach in which a rigid fixation is done in the middle of the curve, while the ends of the rods are linked to flexible connectors that can slide while the child grows. No long-time results are presently available for either system, so no general recommendations can be given.

On Reliability of М.н. Mehta Prognostic Test

Objective. Validation of the Mehta sign reliability on dynamic spine radiographs of patients with progressive idiopathic scoliosis. Material and Methods. Radiographs of 65 patients with progressive idiopathic right-side thoracic scoliosis examined in dynamics were analyzed. The rib-vertebra angle difference (RVAD) was assessed in accordance with Mehta techniques, and scoliosis evolution was followed up. Results. Initial RVAD in 35 patients was less than 20°. Deformity progressed with time in all patients, and in 71 % of them it evolved into a severe form. Almost half of these patients (43 %) have a curve of 30° to 63° even at initial examination. Equality of rib-vertebra angles (RVA-L and RVA-R) does not indicate the absence of scoliosis. Nine patients (26 %) with equal RVA had the Cobb angle of deformity of 6° to 28°. Conclusion. Our findings raise doubt on reliability of the Mehta sign. Further research is necessary including series of patients with non-progressive forms of idiopathic scoliosis.

Vertebral Rotation and Thoracic Torsion in Adolescent Idiopathic Scoliosis

As a result of the increased appreciation of the three-dimensional nature of scoliosis and modern spinal instrumentation's improved corrective capabilities, there has been renewed interest in the correction and measurement of vertebral rotation. Computed tomography (CT), the gold standard for accuracy, is limited in its clinical utility owing to cost, radiation exposure, and the effects of postural changes on scoliosis curves and vertebral rotation. Consequently, the Perdriolle and Nash-Moe techniques remain the standard measurements for providing a reasonable estimate of pre- and postoperative vertebral rotation because of their simplicity. However, these techniques have considerable interobserver variability, and pedicle screw instrumentation obscures the landmarks necessary for utilizing these techniques for postoperative vertebral rotation assessment. The purpose of the present study was to assess the utility of alternate radiographic measures to assess vertebral rotation and thoracic torsion when compared with conventional measures on pre- and postoperative radiographs and CT evaluation. We reviewed the preoperative, immediate postoperative, and final follow-up radiographs, as well as the pre- and postoperative CT scans, of 19 patients (average age 15 years, 6 months) with Lenke 1 curves (average 55 degrees , range 47-66 degrees ), all treated with anterior spinal fusion. Coronal and sagittal Cobb angles as well as vertebral rotation (Perdriolle and Nash-Moe) at the superior uninstrumented, superior instrumented, apical, inferior instrumented, and inferior uninstrumented vertebrae were measured on all films, and vertebral rotation was assessed on the CT scans by a previously described method. Additionally, several measures of thoracic torsion (as a proxy for vertebral rotation and overall deformity improvement) were assessed. These included the rib-vertebral angle difference (RVAD), apical rib hump prominence (RH), apical vertebral body-rib ratio (AVB-R), and apical rib spread difference (ARSD). The postoperative main thoracic curve averaged 26 degrees (range 16-39 degrees , 52% correction) and 29 degrees (range 22-40 degrees , 47% correction) at final follow-up. For apical derotation, the postoperative CT improved from -11.5 degrees to -6.6 degrees and correlated significantly with the Cobb main thoracic curves (42% correction, r = 0.48, P = 0.003). There was weakly positive, but statistically significant, correlation between the pre- and postoperative CT scans and the corresponding Perdriolle and Nash-Moe measures of segmental rotation (r = 0.32-0.40, all P < 0.0001). The RVAD demonstrated poor correlation with the main thoracic curve values and correction, Perdriolle rotation and correction, and CT rotation and correction (r = -0.22-0.37, all P > 0.20). The apical RH demonstrated good correlation with the main thoracic curve (r = 0.65, P < 0.0001), apical Perdriolle rotation (r = 0.57, P < 0.0001), and CT apical rotation (r = 0.53, P = 0.002). We also found moderate correlation between the AVB-R and the main thoracic Cobb, apical Perdriolle, and CT (r = 0.57, 0.59, and 0.49, respectively; all P < 0.005). Similar relationships were found with the ARSD (r = 0.51, 0.47, and 0.43, respectively; all P < 0.02). The RH, AVB-R, and the ARSD-measures of thoracic torsion-demonstrated moderate to good overall correlation with the main thoracic curve Cobb angles, apical Perdriolle rotation, and apical CT rotation. These should be useful as clinical measures for assessing three-dimensional deformity correction on plane radiographs, especially for the intraoperative evaluation of vertebral derotation and thoracic symmetry restoration.

Colour Doppler ultrasonography for evaluation of anterior chest blood supply: the possible role of arterial blood supply to the costosternal junction in the aetiology of idiopathic scoliosis in female adolescents.

This prospective comparative study was carried out to investigate the blood supply to the anterior chest wall by measurement of several anatomical and haemodynamic flow parameters of the internal mammary artery, with the use of colour Doppler ultrasonography, in female scoliotics with idiopathic right convex scoliosis in adolescence. Previous investigations have postulated that asymmetry of the breasts in female adolescents may be linked with the development of right convex thoracic scoliosis. This breast asymmetry is supposed to be linked with anatomical and functional asymmetry of the internal mammary artery that is the main supplier to the mammary gland. However, no measurements of anatomical and haemodynamic parameters of the internal mammary artery have been made to justify or reject the hypothesis of asymmetric blood flow volume to the breasts and costosternal junction in female adolescent scoliotics. Twenty female adolescents with right convex thoracic scoliosis and 16 comparable female individuals without spine deformity were examined with roentgenograms (scoliotics only) to measure scoliosis curve, vertebral rotation and concave and convex rib-vertebra angle at three vertebrae (the apical, one level above and one below the apical vertebra). Doppler ultrasonography was used to measure, at the origin of the internal mammary artery, its lumen diameter, cross-sectional area, time average mean flow and flow volume per minute in scoliotics and controls, which were compared with each other. The roentgenographic parameters were compared with the ultrasonographic parameters in the scoliotics to disclose any relationship. The reliability of colour Doppler ultrasonography was high and the intra-observer variability low (ANOVA, P=0.92-0.94). There was no statistically significant difference in the ultrasonographic parameters of the internal mammary artery between right and left side in each individual as well as between scoliotics and controls. In scoliotics the right mammary artery time average mean velocity increases with the convex ( P<0.05) and concave ( P<0.01) rib-vertebra angle one level above the apical vertebrae and with the apical convex rib-vertebra angle ( P<0.05). The right internal mammary artery flow volume per minute increases with convex ( P<0.01) and concave ( P<0.01) rib-vertebra angle one level above the apical vertebrae and with the apical convex rib-vertebra angle ( P<0.05). Left internal mammary artery cross-sectional area increases with convex apical rib-vertebra angle ( P<0.01) and concave rib-vertebra angle one level above the apical vertebra ( P<0.01). Conclusively, this investigation showed that haemodynamic flow parameters of the right internal mammary artery and anatomical parameters of the left internal mammary artery are significantly correlated with the magnitude of rib-vertebra angles close to the apex of right thoracic scoliosis in female adolescents. This study did not find any evidence for side-difference in vascularity of the anterior thorax wall and, thus, it could not clearly justify previous theories for development of right thoracic scoliosis in female adolescents.

Reviewer?s comment on MS no. 02/156: ?Colour Doppler ultrasonography for evaluation of anterior chest blood supply: the possible role of arterial blood supply to the costosternal junction in the aetiology of idiopathic scoliosis in female adolescents? (P. Korovessis et al.)

This is an original piece of work exploring a possible link between asymmetries of blood supply and any effects on soft tissue and bone development of the chest wall, comparing scoliotics with non-scoliotics. A possible conclusion is that over-development or atrophy of the blood supply may be a primary factor governing the rib growth, but, on the other hand, it may be secondary, if, indeed, such asymmetries exist at all. The authors have discovered that Colour Doppler ultrasonography may be used reliably to measure anatomical and flow characteristics of the internal mammary artery on each side, close to its origin at the first three intercostal spaces. In this closely argued and densely statistical paper the authors conclude that, in right-sided, adolescent, idiopathic scoliotics, blood flow increases in the right internal mammary artery, together with increases in the apical rib–vertebral angles on the convex and concave sides. The cross-sectional area is not changed. On the other hand, the cross-sectional area of the left internal mammary artery is increased in proportion to an increase in convex and concave apical rib–vertebral angles. These somewhat conflicting findings do not indicate a simple correlation between increased blood supply and rib overgrowth as a primary or secondary feature of right-sided, idiopathic scoliosis in adolescence. Indeed, an explanation for these apparently statistically valid differences cannot be derived from this study. We will have to wait with interest for further longitudinal studies to see if they offer any aetiological or prognostic indicators of the natural history of an individual, idiopathic curvature in adolescence. No doubt this is wishful thinking, but the authors should certainly be encouraged to continue their efforts in this potentially important area.

The association between arterial blood supply to the anterior chest and juxta-apical thorax-asymmetry-associated right thoracic female adolescent idiopathic scoliosis

This cross-sectional study was carried out to investigate the role of arterial blood supply to the anterior chest wall in the pathogenesis of idiopathic scoliosis in adolescent females. Previous investigations have postulated that there is some asymmetry of the breasts in female adolescents with thoracic scoliosis that may be linked with anatomic and functional asymmetry of the internal mammary (IMA) artery that is the main supplier to the mammary gland. For this reason the present study investigated several anatomic and hemodynamic flow parameters of the IMA with color Doppler ultrasonography (CDU). Twenty female adolescents with right convex thoracic scoliosis were examined with roentgenograms to measure scoliosis curve, vertebral rotation, and concave and convex rib-vertebra angle at three vertebrae (apical, and one level above and one below the apical vertebra). Sixteen comparable nonscoliotic females were used as controls. CDU measured the IMA lumen diameter, its cross-sectional area, time average mean flow, and flow volume per minute. In scoliotics the obtained roentgenographic and ultrasonographic parameters were compared with each other to disclose any relationship. The reliability of CDU was high and the intraobserver variability low (ANOVA, P=0.92–0.94). There was no statistically significant difference in the ultrasonographic parameters of the IMA between right and left side in each individual or between scoliotics and controls. In scoliotics significant (P<0.05–0.01) correlations were shown between anatomic and hemodynamic parameters of internal mammary artery and juxta-apical convex and concave rib-vertebra angle. This study showed that the blood supply to the anterior chest wall in female adolescent scoliotics suffering from right-convex thoracic scoliosis is significantly correlated with juxta-apical convex and concave rib-vertebra angles. Thus, although this study found no correlation between scoliosis characteristics and anterior wall blood supply, it theoretically supports the hypothesis of a possible correlation between juxta-apical thorax asymmetry and anterior chest-wall blood supply in idiopathic scoliosis.

The effects of pineal gland transplantation on the production of spinal deformity and serum melatonin level following pinealectomy in the chicken.

Pinealectomy frequently produces spinal deformity in some animal models, but the precise biological mechanism of this phenomenon remains obscure. The current study investigated the effects of an autograft pineal body on the development of spinal deformity and serum melatonin (MLT) concentration after pinealectomy in the chicken. Thirty-six chickens (2 days of age) were divided into three equal groups. While the removal of the pineal gland was performed in groups B and C, a pineal body autograft was surgically implanted into the body wall musculature only in the pineal transplantation group (group C). Chickens in which no surgical intervention was performed served as intact controls (group A). Posteroanterior radiographs of the spines of the chickens were taken at the age of 8 weeks. These were used to determine Cobb angles and to measure the rib-vertebra angles (RVA) on the concave and convex sides of the curves, from which data the difference between the convex and concave RVA (the RVAD) was calculated. At the end of the study, serum MLT levels were determined using the enzyme-linked immunosorbent assay method, and histopathological examination of specimens from all the groups was performed. The results were compared using one-way analysis of variance followed by Duncan's test for pairwise comparisons or by the Kruskal-Wallis test followed by the Mann-Whitney U tests for comparisons between two groups. In this study, the serum MLT levels in groups B and C were significantly lower than those in group A ( P<0.05). However, scoliosis developed in only 7 of 12 (58%) in group B and 6 of 12 (50%) in group C. The average Cobb angle and RVAD in groups B and C were significantly larger than those found in group A ( P=0.000 and P=0.001, respectively). Interestingly, there were no significant differences in either serum MLT levels or development of scoliosis between groups B and C. From the results of the current study, it is evident that the intramuscular pineal gland transplantation following pinealectomy in young Hybro Broiler chickens has no significant effect on the development of spinal deformity and serum MLT level. In the light of this result, the role of MLT in the development of spinal deformity in chickens after pinealectomy remains controversial, and further investigations are warranted.

Prevention of the Crankshaft Phenomenon with Posterior Pedicle Screw Fixation in Scoliosis of the Skeletally-Immature Spine

Study Design: A retrospective study. Objectives: To evaluate the results of posterior segmental pedicle screw fixation in skeletally immature patients with scoliosis. Summary of Literature Review: Scoliosis correction, in the immature spine, frequently necessitates additional anterior surgery to prevent the crankshaft phenomenon. With the advent of posterior segmental pedicle screw fixation, it is unclear whether an additional anterior procedure will be required. Material and Methods: Seventeen scoliosis patients (10 idiopathic, 4 congenital and 3 others; 3 males and 14 females) were treated with segmental pedicle screw fixation only. Their results were reviewed for a deformity progression of more than 10 ○ , a rib vertebra angle difference (RVAD) progression of more than 10 ○ , and evidence of adding-on. All the patients had a 0 Risser index at the time of the operation. The mean age and follow-up times were 10.4, ranging from 7.2 to 11.8 years old, and 4.0, ranging from 3.0 to 5.4 years, respectively. Results: The mean preoperative thoracic curve of 55 ○ was corrected to 22 ○ (58% correction) at last follow-up and the nonstructural lumbar curve of 31 ○ was corrected to 10 ○ (67% correction) at last follow-up. Preoperative thoracic kyphosis of 28 ○

Long-term observation and management of resolving infantile idiopathic scoliosis

Of 42 patients with resolvingscoliosis, 34 were followed up for more than 25 infantile idiopathicyears. Twenty had been primarily treated in a plaster bed and 14 by physiotherapy. The mean angle of the curve at presentation was 17° and at follow-up it was 5°. No patient had significant progression of the scoliosis during the growth spurt. When adults few had back pain or an increased disability score and there was no interference with work or social activities. The rib-vertebra angle difference proved to be an essential radiological sign when distinguishing resolving from progressive infantile idiopathic scoliosis. There was no advantage of plaster over physiotherapy with regard to either the time to resolution or the functional outcome. Treatment of resolving infantile idiopathic scoliosis in a plaster bed is therefore now outdated.

Long-term observation and management of resolving infantile idiopathic scoliosis a 25-year follow-up.

Of 42 patients with resolving infantile idiopathic scoliosis, 34 were followed up for more than 25 years. Twenty had been primarily treated in a plaster bed and 14 by physiotherapy. The mean angle of the curve at presentation was 17 degrees and at follow-up it was 5 degrees. No patient had significant progression of the scoliosis during the growth spurt. When adults few had back pain or an increased disability score and there was no interference with work or social activities. The rib-vertebra angle difference proved to be an essential radiological sign when distinguishing resolving from progressive infantile idiopathic scoliosis. There was no advantage of plaster over physiotherapy with regard to either the time to resolution or the functional outcome. Treatment of resolving infantile idiopathic scoliosis in a plaster bed is therefore now outdated.

Juvenile-Onset Scoliosis Followed up to Adulthood: Orthopaedic and Functional Outcomes

This retrospective review describes 52 children with juvenile-onset scoliosis followed up for at least 2 years after skeletal maturity and completion of treatment. The purpose was to compare clinical and radiographic characteristics and curve progression, as well as orthopaedic, functional, and psychosocial outcomes in children treated by observation, bracing, or surgery. Seventeen percent of patients were treated with observation and 33% with bracing; and 50% required surgery. Median rib-vertebral angle difference and mean level of apical vertebra differed by treatment group. Neither brace nor surgical treatment negatively affected self-esteem. Results suggest that juvenile scoliosis is more likely to progress, less likely to respond to bracing, and more likely to require surgical treatment than adolescent idiopathic scoliosis.

Factors that influence outcome in bracing large curves in patients with adolescent idiopathic scoliosis.

A retrospective review of 51 patients with adolescent idiopathic scoliosis (AIS) treated with a Boston brace for curves ranging from 36 degrees to 45 degrees. To determine what radiographic or clinical observations may be predictive of outcome. Patients with AIS who are braced for curves >35 degrees are less likely to respond to conservative treatment than patients of similar maturity with smaller curves. Skeletally immature patients with AIS with no history of prior treatment were treated with a Boston brace. Cobb angles, vertebral tilt angles, coronal decompensation, apical vertebral translation(s), apical vertebral rotation, lateral trunk shift, rib vertebral angle difference, pelvic tilt, and the lumbar pelvic relationship (LPR) were measured at brace prescription, initial in-brace, brace discontinuation, and follow-up. At the time of brace discontinuation, 31 patients (61%) were judged treatment successes. With follow-up observation, an additional eight patients progressed beyond 5 degrees, and a total of 16 patients (31%) required surgical correction. Only patients with double curves were found to have radiographic values predictive of outcome. The LPR angle, the association between the thoracic curve vertebral tilt angles and the amount of in-brace correction of the Cobb angle, were significant predictors. A patient's reported wear schedule significantly influenced outcome. Patients with a double curve pattern in which the thoracic curve is >35 degrees and the LPR angle is >12 degrees are significantly more likely to demonstrate curve progression. In-brace correction for double curves of at least 25% and a patient's ability to wear the orthosis >18 hours/day significantly increased the likelihood of success.

Effects of thoracolumbosacral orthosis on spinal deformities, trunk asymmetry, and frontal lower rib cage in adolescent idiopathic scoliosis.

Prospective study. To document immediate and late changes in shape and balance of the thoracic and lumbar spine and lower rib cage on the frontal plane induced by treatment with a thoracolumbosacral orthosis (TLSO). The effect of TLSO on lateral plane of spinal deformity, frontal lower rib cage, trunk balance, and natural history are poorly understood. Twenty-four female adolescents with major thoracic and/or lumbar scoliosis, averaging 30 degrees and 26 degrees, respectively, were treated with a full-time TLSO program. Scoliosis, kyphosis, convex, and concave rib-vertebral angles T7 to T12, frontal trunk balance, frontal vertebral inclination, rotation and translation from T7 to L4-vertebrae were measured before bracing, 1 month after bracing, and biannually thereafter in brace and without brace for a 4-year period and reevaluated at the age of 20 years, at an average of 3.5 years after termination of bracing to measure any permanent changes. Thoracolumbosacral orthosis treatment corrected both thoracic and lumbar scoliosis and reduced lateral trunk shift at the expense of significant, although temporary reduced physiological thoracic kyphosis, increased lateral displacement of T7 to T10, increased frontal inclination of L2 to L4, and elevation of the apical concave rib in favor of reduction of lateral displacement of T11 to L4; decreased frontal inclination of T7, T9, and T11; and derotated L1 and L2 and thoracic apical vertebra without affecting drooping of the 7th to 12th ribs. In this series, there was marked inconsistency in the obtained changes in several of the roentgenographic parameters in the different evaluations, which is probably because of the empiric application of the TLSO during different periods of treatment. 3.5 years after termination of TLSO-wearing, all roentgenographic parameters remained to the prebrace values. Thoracolumbosacral orthosis program maintained the measured roentgenographic parameters at the prebrace levels in progressive adolescent idiopathic scoliosis, but it had no effect on the droop of the seven lower ribs. The TLSO treatment stopped progression of scoliosis and reduced the number of patients requiring surgery. Thus, it changed the natural history of scoliosis.

Scoliosis correction maintenance in skeletally immature patients with idiopathic scoliosis. Is anterior fusion really necessary?

A retrospective evaluation of the occurrence of the crankshaft phenomenon in skeletally immature patients with idiopathic scoliosis. To determine what factors, if any, contribute to a decreased occurrence of crankshaft phenomenon in patients treated with posterior surgery only. Reports have described the progression of scoliotic deformity, termed the crankshaft phenomenon, in a region of solid posterior arthrodesis in skeletally immature patients. This has led some authors to advocate the use of concomitant anterior discectomy and fusion to prevent crankshaft. From 1989 through 1994, 18 Risser 0 patients with thoracic or thoracolumbar idiopathic scoliosis underwent Isola (De Puy-Acromed, Raynham, MA) posterior instrumentation and fusion. They were assessed for evidence of the crankshaft phenomenon, identified by coronal plane deformity progression of 10 degrees or more, or a rib vertebra angle difference of 10 degrees or more. The average age of the patients was 12.5 years (range, 10.5-15.5 years), and the average follow-up period was 39 months (range, 24-68 months). Eleven patients (10 girls and 1 boy) had closed triradiate cartilage at the time of surgery. Their average Cobb angle was 62 degrees before surgery, 21 degrees after surgery, and 22 degrees at follow-up assessment. No patients in this group met the criteria for crankshaft. Seven patients (6 girls and 1 boy) had open triradiate cartilage at the time of surgery. Their average Cobb angle was 62 degrees before surgery, 18 degrees after surgery, and 20 degrees at follow-up evaluation. No patient had a 10 degrees or more increase in rib vertebra angle difference. One patient had more than a 10 degrees increase in her Cobb angle (11 degrees) from postoperative to latest follow-up assessment. Her instrumentation construct, performed in 1989, used sublaminar wires as the caudal anchors. Hooks and pedicle screws are now used. Two of the seven patients with open triradiate cartilage underwent surgery during or before their peak height velocity and displayed no evidence of crankshaft. No deaths, neurologic complications, or infections occurred in either group. These findings suggest that scoliotic deformity progression can be prevented in skeletally immature patients with idiopathic scoliosis as young as 10 years of age with the use of stiff segmental posterior instrumentation, without the necessity of concomitant anterior arthrodesis.

Infantile idiopathic scoliosis in the newborn.

We have reviewed 7 patients (5 boys and 2 girls) with infantile idiopathic scoliosis which was present at birth and was diagnosed at ages from 1 day to 1 month. The mean follow up was 16 years. The objectives were to discover whether intrauterine forces play a role in the aetiology and to determine whether early treatment of a potentially progressive curve can induce resolution. Two infants were male conjoined twins and were united by skin over the posterior sacrum. Six infants had a rib vertebral angle difference greater than 20 degrees in the first radiograph and 5 had stiff curves. In 2 with flexible curves, the deformity disappeared by the end of the first year. The 5 with stiff curves were treated conservatively for 6 to 24 months. Growth has now been completed in 5; 4 have a straight spine and one developed an adolescent curve of 26 degrees. The 2 who are still growing have no scoliosis. Intrauterine moulding was only demonstrated in the conjoined twins. There was a correlation between the rib vertebral angle difference above 20 degrees and the rigidity of the curve. Early treatment of a potentially progressive curve can lead to resolution.

Posterior arthrodesis in the skeletally immature patient. Assessing the risk for crankshaft: is an open triradiate cartilage the answer?

Thirty-three skeletally immature patients younger than 12 years of age and having posterior arthrodesis and evidence of solid posterior fusion without "adding on" were retrospectively reviewed. All patients had a minimum of 5 years of follow-up. To ascertain factors associated with crankshaft and to determine how accurate a marker the triradiate cartilage was. All patients had Risser Stage 0 curves and all of the girls were premenarchal preoperatively. The average age was 9 years 3 months (range, 2 years-11 years 11 months). Preoperative diagnoses consisted of 14 idiopathic, 11 congenital, five dysplastic, and three neuromuscular etiologies. Preoperatively, within 3 months after surgery, and at 2-year, 5-year, and final postoperative follow-up, the following radiographic parameters were reviewed: coronal Cobb, apical vertebral rotation, apical vertebral translation, rib vertebral angle difference, and trunkshift. The triradiate cartilage was open in 24 patients at the time of operation. Of those 24, only nine (37.5%) had documented proof of crankshaft. Patients with closed triradiate cartilage had no significant postoperative increase in radiographic parameters (0 of 9). The subgroup of patients with idiopathic scoliosis had an average age of 11 years 3 months (range, 9 years 2 months-11 years 11 months). Five of 14 patients had an open triradiate cartilage. All were followed up to skeletal maturity. None had significant progression in postoperative radiographic parameters. This study did not find an open triradiate cartilage to be an absolute prognostic indicator for the occurrence of crankshaft. Additional refinement of markers of maturity are needed to determine who requires anterior arthrodesis.

Rib-vertebral angle asymmetry in idiopathic, neuromuscular and experimentally induced scoliosis.

The concave and convex rib-vertebral angle (RVA) at levels T2-T12 was measured on AP radiographs of 19 patients with right convex idiopathic thoracic scoliosis and 10 patients with major thoracic right convex neuromuscular scoliosis. The difference between the angles on the concave and the convex sides, the RVAD, was calculated. The RVAs were also measured on radiographs from three animal groups in which spinal curves had been induced experimentally in a variety of ways. Group 1 comprised 16 rabbits that had been subjected to selective electrostimulation of the latissimus dorsi, the erector spinae and the intercostal muscles. Group 2 comprised four dead rabbits whose spines had been subjected to manual bending. Group 3 comprised eight rabbits that had undergone mechanical elongation of one rib. In both the idiopathic and the neuromuscular group, the convex RVA was smaller than the concave RVA between levels T2 and T8, with a maximal difference between T4 to T5. From T9 to T12 the concave RVA was smaller than the convex. The RVA in relation to the scoliotic segment, i.e. the apex level of the curve and the two neighbouring vertebrae above and below this level, showed similar results. With increasing Cobb angle the RVADs increased linearly with the greatest difference at the second vertebra above the apex. In the three experimental groups the pattern of the RVADs between T6 to T12 was basically similar to the findings of the clinical study. From the results of these clinical and experimental studies, it is concluded that the typical pattern of the RVAs on the concave and convex sides seems to be independent of the underlying cause of the spinal curvature. It is likely that the RVADs result from a passive mechanical adaptation of the ribs to the lateral curvature of the spine.

Measurement of rib vertebral angle difference. Intraobserver error and interobserver variation.

The rib vertebral angle difference was measured on 50 juvenile scoliosis radiographs. Three observers measured each radiograph independently and on three separate occasions to determine interobserver and intraobserver error. To determine the interobserver and intraobserver error in measuring the rib vertebral angle difference. The rib vertebral angle difference is a commonly used measurement, the reliability of which has not been tested rigorously. Fifty standing radiographs of juvenile scoliosis were measured. All patients were Risser 0 at the time of measurement. All angles were measured by the method of Mehta using the same protractor and apical vertebra to avoid confounding variables. Three surgeons individually measured the 50 radiographs randomly and on three separate occasions. All markings were erased before remeasurement. The intraobserver error was determined to be 4.4 degrees. The interobserver error was 3.6 degrees. The interobserver accuracy was 6.2 degrees. The rib vertebral angle measurement is highly reproducible and is a valid measurement.