Brace effect in scoliosis in the sagittal plane - an MRI study

AIM: Using magnetic resonance (MR) imaging we studied the brace effect in scoliosis in the sagittal plane. METHOD: In 38 patients with idiopathic scoliosis (mean age 13.4 years) MR total spine imaging was carried out to investigate the immediate effect of bracing in the sagittal plane. There were 19 thoracic, 13 S-shaped and 6 lumbar scoliosis. On conventional radiographs the mean Cobb angle of the thoracic curves was 31 degrees and of the lumbar curves 26 degrees. MR imaging was performed in the supine position with and without the brace in direct sequence. On the sagittal MR projection the Cobb angle was measured between T 4 and T 12 and between T 12 and L 5. RESULTS: On the coronal MR images the mean correction with brace was 23 % of the thoracic curves and 29 % of the lumbar curves. The mean, sagittal Cobb angle (T 4 - T 12) was 14 degrees without brace and 12 degrees with brace. For the lumbar curves the mean sagittal Cobb angle (T 12 - L 5) was 32 degrees without brace and 31 degrees with brace. In the paired t-test these differences were significant. CONCLUSION: Using MR total spine imaging the brace effect in scoliosis could be depicted in the sagittal plane. In the thoracic spine a correction of the lordotic deformity could not be observed.     

Segmental vertebral rotation in early scoliosis

Summary In order to investigate the development of the vertebral axial rotation in patients with early scoliosis, the vertebral rotation angle (VRA) was quantified on the basis of 132 anteroposterior radiographs obtained from patients with diagnosed or suspected scoliosis. The rotation was measured in the apical vertebra and in the two suprajacent and two subjacent vertebrae. The radiographic material was divided into a control reference group and three scoliotic groups with varying Cobb angle from 4° up to 30°. In the reference group a slight vertebral rotation was significantly more often seen to the right. In the scoliotic groups, the rotation was most pronounced in the apical segments. The mean VRA toward the convex side was significantly increased in the vertebrae just suprajacent to the apex in curves with a Cobb angle of 8°–15° and in the cranial four vetebrae in curves with a Cobb angle of 16°–30°. Atypical vertebral rotation to the opposite side of the major curve was observed in 12.8% of the cases. There was a significant positive correlation between the VRA and the Cobb angle. These results show that a slight VRA to the right is a common feature in the normal spine, and that the VRA increases with progressive lateral deviation of the spine. It is concluded that the coronal plane deformity in early idiopathic scoliosis is accompanied and probably coupled to vertebral rotation in the horizontal plane.     

A new method of MR total spine imaging for showing the brace effect in scoliosis

Bracing is a method of early, nonsurgical treatment for scoliosis, but a hypokyphotic effect on the thoracic spine is reported. We developed a magnetic resonance tomography (MR) procedure presenting an image of the whole spine in the coronal and sagittal planes (MR total spine imaging), and studied the brace effect, using this technique. We examined 26 female patients with idiopathic scoliosis treated with a Cheneau brace (mean age, 13.2 years; mean duration of brace treatment at the time of investigation, 1.5 years). The MR examinations were performed with the patient in the supine position with and without the brace in direct sequence. As measured on the coronal MR images, the thoracic curve was corrected, on average, from 29° to 22° (mean correction, 24%). There was a slight reduction in the sagittal Cobb angle measured between T4 and T12 (mean sagittal Cobb angle without brace, 14°; with brace, 12°), which was still a significant change. MR total spine imaging could be a useful tool for studying the brace effect in scoliosis in two planes. Using this technique, we found reduced sagittal Cobb angles for the thoracic kyphosis with brace. Because there is no radiation exposure, the MR procedure has a potential use in the monitoring of brace treatment. Received: November 13, 2000 / Accepted: March 6, 2001     

Idiopathic scoliosis: prognostic value of the profile

Summary A study was undertaken to establish the significance of the sagittal shape of the spine in 138 consecutively treated girls with early idiopathic thoracic scoliosis. All were treated in a Boston brace. Two groups were formed: group I consisted of 120 girls whose scoliosis remained stable in the brace, group II of 18 girls who required a spinal fusion for progressive curves despite the brace. For each spine, the orientation of each vertebra to the horizontal in the sagittal plane was measured on the earliest lateral radiogram, taken when the anterior curve still had a Cobb angle of less than 20°. A significant difference in spinal profile was found between the two groups. Progressive curves showed a more retroverted orientation of mid- and high thoracic vertebrae than stable curves.     

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

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

Reductibility of idiopathic scoliosis during orthopedic treatment

Non-operative treatment of idiopathic scoliosis is long and difficult. For the patient and the therapist it is particularly important to define early the therapeutic prognosis. The goal of this study is to verify if the initial reducibility at the beginning of treatment with the dynamic corrective brace (Spinecor) would be valid as a prognostic factor, allowing a more effective prognostic judgement of the final outcome treatment. This is a prospective study which includes 99 scoliosis patients (88 female, 11 male), with a mean age of new 12.6 years, treated by the dynamic corrective brace for progressive idiopathic scoliosis curves (29 degrees mean Cobb angle). The initial Cobb angle was compared to the pre-therapeutic Cobb angle. The results demonstrate that the reducibility of the scoliotic curves with the brace at the beginning of treatment provides a significant global prognostic index but is difficult to apply individually. Other factors should be considered, such as the impact of growth velocity on the spinal deformity at the onset of the adolescent growth spent as well as vertebral deformities diagnosed around the apex.     

Curve progression and spinal growth in brace treated idiopathic scoliosis

The risk of progression of idiopathic scoliosis is correlated primarily to factors that predict potential remaining skeletal growth. The aim of the current study was to evaluate spinal growth, measured as the length of the scoliotic spine on serial longitudinal radiographs, and its relationship to progression of the scoliotic curve. The retrospective study was based on measurements made on standing anteroposterior radiographs of 60 patients with adolescent idiopathic scoliosis. In all patients, a Boston brace was prescribed during the followup period. Despite brace treatment, a significantly greater average progression rate of the scoliotic curve was seen in periods of rapid to moderate growth (> or = 10 mm per year) compared with periods of small or no growth (< 10 mm per year). The difference in progression rates concerned the increase of the Cobb angle and the increase of lateral deviation and axial rotation. These findings indicate the length of the spine measured on subsequent radiographs is an excellent parameter to determine spinal growth and thus an excellent predictor of scoliosis progression. With the presented growth charts, which were derived from the measured individual growth velocity values of the patients in the study, it is possible to predict future spinal growth at different chronologic ages.     

A new MRI technique for imaging scoliosis in the sagittal plane

The purpose of the present study was to introduce a new magnetic resonance imaging (MRI) procedure showing the whole spine in a coronal and sagittal plane, and to study the assessment of sagittal Cobb angle measurements using this technique. Prospectively we studied 32 patients (average age 14.8 years) with idiopathic scoliosis (mean thoracic Cobb angle 33 degrees on radiograph) and 18 patients (average age 14.5 years) without scoliosis. The MRI investigation was carried out in a standard supine position. The cervical and upper thoracic spine and the lower thoracic and lumbar spine were measured on a 1.5-T Gyroscan ACS-NT Powertrak 6000 system. An algorithm was developed to combine the results of the cranial and caudal scans into a coronal and a sagittal image of the whole spine (MR total spine imaging). Measurement of the sagittal Cobb angle conducted ten times by four independent investigators revealed an intraobserver variance of 1.6 degrees and an interobserver variance of 1.8 degrees. In the group with scoliosis the mean sagittal Cobb angle from T4 to T12 was 12 degrees (range -3 degrees to 24 degrees) and in the group without scoliosis 22 degrees (range 16 degrees to 30 degrees), which was a significant difference. MR total spine imaging makes it possible to image scoliosis in the sagittal plane. On these MR projections, idiopathic thoracic scoliosis was identified by a reduced sagittal Cobb angle. MR total spine imaging would allow monitoring of scoliosis in the sagittal plane, which can reveal relevant clinical data without radiation exposure.     

Sagittal Cobb-angle measurements in scoliosis with MRI whole spine imaging

AIM: A newly developed MR procedure allows imaging of the whole spine in coronal and sagittal planes. We studied the use of total spine MR imaging in measuring sagittal Cobb angles in scoliosis. METHOD: 64 patents with idiopathic scoliosis (mean age 18.1 years, 35 thoracic, 20 double major, and 9 lumbar curves) and 27 patients without scoliosis were consecutively examined. The MR images were acquired in the supine position. The sagittal Cobb angles were measured between T4-T12 and between T12-L5. RESULTS: For the group of the thoracic and double major scoliosis the mean sagittal Cobb angle (T4-T12) was 13 degrees and for the group without scoliosis 23 degrees, which was a significant difference (p < 0.01, Mann Whitney-U-test). There was a negative correlation between the sagittal Cobb angles (T4-T12) and the lateral, thoracic curves. The mean sagittal Cobb angle (T12-L5) of the group with lumbar and double major curves was 35 degrees, which was not a significant difference when compared to 37 degrees of the non-scoliotic group. CONCLUSION: Using total spine MR imaging the lordotic aspect of the thoracic deformation in scoliosis can be reliably measured. Because of the absent radiation exposure the sagittal MR reconstructions could be used as an additional imaging in monitoring scoliosis.     

Correction of flexible thoracic scoliosis below 65 degrees—A radiological comparison of anterior versus posterior segmental instrumentation applied to similar curves

Direct comparison of the correction of scoliosis achieved by different surgical methods is usually limited by the heterogeneity of the patients analyzed (their age, curve pattern, curve magnitude, etc.). The hypothesis is that an analysis of comparable scoliotic curves treated by different implant systems could detect subtle differences in outcome. The objective of this study was therefore: (1) to measure the 3D radiological parameters of scoliotic deformity and to quantify their postoperative changes, and (2) to compare the radiographic results achieved with one anterior and one posterior instrumentation methods applied to similar curves but representing different mechanisms of correction. Material and methods: The clinical notes and radiographs of 46 patients operated on for adolescent idiopathic scoliosis were reviewed. The inclusion criteria consisted of: a single thoracic curve, right convex, a frontal Cobb angle minimum of 45° and a maximum of 65°, flexibility on a lateral bending test of more than 30%, and a Risser test value of between 1 and 4. The operative procedures were: Cotrel-Dubousset instrumentation (CDI) for 25 patients (the CD group) and correction by anterior instrumentation (Pouliquen plate) for 21 patients (the ANT group). Preoperative and postoperative long cassette standing antero-posterior and lateral radiographs were examined. The frontal and sagittal thoracic Cobb angle, apical vertebra transposition (AVT), apical vertebra rotation (AVR), lowest instrumented vertebra (LIV) tilt, C7 vertebra shift and rib cage shift (RCS) were all compared. A computed reconstruction was produced with Rachis-91 software. Vertebral axial rotation angle was evaluated throughout the spine. Results: Postoperative assessment revealed a mean correction of the frontal Cobb angle of 37.0° for the CD group and 41.0° for the ANT group. The AVT operative correction was 45.8 and 42.7 mm, respectively, and AVR correction was 1.8 and 12.6°, respectively. The postoperative change of the sagittal Th4–Th12 Cobb angle was not significant for any method but it was significant (P=0.05) for the CD group if the curves were divided preoperatively into hypokyphotic and normokyphotic subgroups and then analyzed separately. Computed assessment demonstrated a correction of segmental axial rotation of more than 50% in the main thoracic curve in the ANT group, significantly more than that in the CD group (P<0.001). Conclusions: Anterior instrumentation provided better correction of the vertebral axial rotation and of the rib hump. CD instrumentation was more powerful in translation and more specifically addressed the sagittal plane: the postoperative thoracic kyphosis angle increased in the hypokyphotic curves and slightly decreased in the normokyphotic curves.     

Novel porcine experimental model of severe progressive thoracic scoliosis with compensatory curves induced by interpedicular bent rigid temporary tethering

Using flexible tethering techniques, porcine models of experimental scoliosis have shown scoliotic curves with vertebral wedging but very limited axial rotation. The aim of this experimental work was to induce a severe progressive scoliosis in a growing porcine model for research purposes. A unilateral spinal bent rigid tether was anchored to two ipsilateral pedicle screws in eight pigs. The spinal tether was removed after 8 weeks. Ten weeks later, the animals were sacrificed. Conventional radiographs and 3D CT‐scans were taken to evaluate changes in the alignment of the thoracic spine. After the first 8 weeks of rigid tethering, all animals developed scoliotic curves (mean Cobb angle: 24.3°). Once the interpedicular tether was removed, the scoliotic curves progressed in all animals during 10 weeks reaching a mean Cobb angle of 49.9°. The sagittal alignment of the thoracic spine showed loss of physiologic kyphosis (Mean: ?18.3°). Axial rotation ranged from 10° to 49° (Mean 25.7°). Release of the spinal tether results in progression of the deformity with the development of proximal and distal compensatory curves. In conclusion, temporary interpedicular tethering at the thoracic spine induces severe scoliotic curves in pigs, with significant wedging and rotation of the vertebral bodies, and true compensatory curves. Clinical Relevance: The tether release model will be used to evaluate corrective non‐fusion technologies in future investigations. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:174–182, 2018.

     

Relationship between gibbosity and Cobb angle during treatment of idiopathic scoliosis with the SpineCor brace

The objective of this study was to quantify the relationship between gibbosity and spinal deformation expressed by the angle of Cobb before and during treatment with a brace for different classes of idiopathic scoliosis patients. As part of the standard treatment with the Dynamic Corrective Brace (SpineCor), 89 idiopathic scoliosis patients underwent an initial radiological examination and gibbosity measurement with a scoliometer wearing and not wearing the brace. The 89 patients were classified in relation to the apex of the scoliosis curves: thoracic (n = 29); thoracolumbar (n = 40); lumbar (n = 7) and double (n = 13). With the dynamic corrective brace, the patients showed a mean decrease of 8.3° for the major Cobb angle, and a mean decrease of 2.3° for their gibbosity. There was a significant positive relationship between gibbosity and Cobb angle with and without the brace for the thoracic and thoracolumbar curves. A linear regression analysis identified a small mean estimation error for the thoracic curves (7.4° no-brace; 2.7° with brace) and thoracolumbar curves (5.2° no-brace; 5.3° with brace), indicating a predictive potential of the scoliometer. The measure of gibbosity with the scoliometer provides a fairly reliable estimation of Cobb angle at the initial clinical examination of a scoliosis patient. However, when initial Cobb angle and gibbosity are considered, the measure of gibbosity when wearing a brace provides the clinician with a highly reliable estimation of the Cobb angle while in a brace. This relationship also exists for the follow-up with a brace, permitting a judgement of the patient’s evolution under the treatment with SpineCor. Received: 23 September 1999 Revised: 9 March 2000 Accepted: 2 May 2000     

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

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

3D analysis of brace treatment in idiopathic scoliosis

Purpose

We have evaluated the effect of bracing in scoliosis on coronal alignment in a cohort of patients. Current literature has not described the specific effect of bracing on the 3D shape of the scoliotic curves. The purpose of this study was to analyze the variability of the 3D effect of bracing on idiopathic scoliosis.

Materials and methods

The spines of 30 patients with adolescent idiopathic scoliosis were reconstructed using biplanar stereoradiography with and without the brace. The Cobb angle, sagittal and pelvic parameters and transverse plane parameters were calculated. The variability and the mean values of each parameter, with and without a brace, were analyzed and compared using a student t test.

Results

The Cobb angle improved in 50 % of patients but remained unchanged in 50 % cases. In 90 % of the cases lordosis was decreased. The thoracic kyphosis was decreased in 26 % cases, unchanged in 57 % of cases and increased in 17 % cases. The AVR was improved (>5°) in 26 % cases, worsened in 23 % and unchanged in 50 %. Only the differences of Cobb angle and the lordosis were statistically significant.

Conclusions

Global statistics of this study concur with the literature. The Cobb angle was significantly improved. It also showed a significant hypolordotic effect. However, the results showed a high variability of the brace treatment effect in almost every parameter. Analysis of this variability by means of 3D reconstructions instead of global statistics should help characterize the mechanisms of correction of brace treatment.     

Sagittal configuration of the spine and growth of the posterior elements in early scoliosis

The early changes of the sagittal alignment of the spine and the asymmetry between the posterior and anterior elements were determined on the basis of 134 lateral and 167 anteroposterior radiographs obtained from a control group and from patients with early scoliosis. The radiographs were allocated into four groups according to the degree of the Cobb angle. In thoracic curves with a Cobb angle of more than 8°, the kyphosis and the vertebral sagittal wedge angle decreased in comparison with the control group. The sagittal-wedge angle of the disc did not change significantly with increasing Cobb angle. The pedicle height in relation to the vertebral height, considered to represent the growth of the posterior element in relation to the growth of the anterior element, was not significantly different in the scoliotic groups as compared with the control group. The results indicate that changes of the sagittal configuration of the spine occur early in idiopathic scoliosis and that they are associated with disturbed growth of the vertebral body but not of the posterior elements. These findings seem to reflect a simulataneous deformation in the coronal and sagittal planes rather than a single growth disturbance in any specific plane.     

Clinical effect of continuous corrective force delivery in the non-operative treatment of idiopathic scoliosis: a prospective cohort study of the triac-brace

A prospective cohort study of skeletally immature idiopathic scoliotic patients treated with the TriaC brace. To determine if the TriaC brace is effective in preventing curve progression in immature adolescent idiopathic scoliotic patients with a very high risk of curve progression based on reported natural history data. The aim of the newly introduced TriaC brace is to reverse the pathologic transverse force pattern by externally applied and continuously present orthotic forces. In the frontal plane the force system used in the TriaC brace is similar to the force system of the conventional braces. However, in the sagittal plane the force system acts only on the thoracic region. In addition, the brace allows upper trunk flexibility without affecting the corrective forces during body motion. In a preliminary study it is demonstrated that the brace prevents further progression of both the Cobb angle and axial rotation in idiopathic scoliosis. Skeletally immature patients with idiopathic scoliosis with curves between 20 and 40° were studied prospectively. Skeletally immature was defined as a Risser sign 0 or 1 for both boys and girls, or pre-menarche or less than 1-year post-menarche for girls. Curves of less than 30° had to have documented progression before entry. The mean age of the patients at the start of treatment was 11.3 ± 3.1 years. All measurements were collected by a single observer, and all patients were followed up to skeletal maturity. Treatment was complete for all participants when they had reached Risser sign 4 and did not show any further growth at length measurements. This was at a mean age of 15.6 ± 1.1 years, with a mean follow-up of 1.6 years post bracing. In our study a successful outcome was obtained in 76% of patients treated with the TriaC brace. Comparing our data to literature data on natural history of a similar cohort shows that the TriaC brace significantly alters the predicted natural history. The current study demonstrates that treatment with the TriaC brace reduces the scoliosis, and that the achieved correction is maintained in some degree after skeletal maturity is reached and bracing is discontinued. It also prevents further progression of the Cobb angle in idiopathic scoliosis. The new brace does not differ from the conventional braces as far as maintaining the deformity is concerned.     

Trunk rotation in scoliosis the influence of curve type and direction in 150 children

We compared the angle of trunk rotation (ATR) from scoliometer readings with Cobb angle measurements of the lateral deviation of the spine in 150 children referred to hospital for evaluation of scoliosis. the mean Cobb angle in thoracic curves was 16 °, in thoracolumbar curves 17° and in lumbar curves 20°. in thoracic curves and in right convex curves no patient with a Cobb angle of 25° or more had an ATR below 9°. in thoracolumbar and lumbar and in left convex curves, 7° ATR was occasionally associated with scoliosis of 25° or more. the correlation coefficient between the ATR and Cobb angle in right convex curves was 0.65 compared to 0.57 in left convex curves. We conclude that a criterion of 7° ATR for thoracic or right convex curves and one of 6° ATR for thoracolumbar and lumbar or left convex curves seem adequate for identification of patients with Cobb angles of 25° or more, which reduces the need for spinal radiography and follow-up outside the school screening programs.     

Moiré topography in scoliosis. Its accuracy in detecting the site and size of the curve

Moiré topography was added to school scoliosis screening in Singapore in 1982. The results from 1342 topographs, assessed in isolation, were used to study the accuracy of the method in predicting the radiographic location and magnitude of scoliotic curves. Accuracy in identifying the site of the curve was 68% in the thoracic spine, 54% in the thoracolumbar spine, and 15% in the lumbar region. There were 12.7% false-positive results and 4.3% false negatives. Of patients with a deviation of one moiré fringe, 76.5% had a curve of 15 degrees or less; of those with a deviation of four moiré fringes, 69% had a curve greater than 26 degrees. The prediction of the Cobb angle was less accurate when there was a deviation of two or three fringes. It is suggested that moiré topography as a screening device should be reserved for use in the second tier of screening, since the forward-bending test is an effective and cheap method for the first tier of a mass school-screening programme.     

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

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

Is there a need for anterior release for 70–90° thoracic curves in adolescent scoliosis?

Large and stiff thoracic scoliotic curves in the adolescent represent a classic indication of anterior release followed by posterior instrumentation. However, third-generation segmental spinal instrumentations have shown increased correction of thoracic curves. Indication for an anterior release may therefore not be required even in large and stiff thoracic curves. The objective of the study was, therefore, to analyze retrospectively the results of third-generation segmental posterior instrumentation in large and stiff thoracic curves and to compare our results with the current literature of anterior release followed by posterior instrumentation. An independent observer, who had not participated in any of the case, reviewed our electronic database of adolescent scoliosis surgery (Scolisoft) with the following query: thoracic curves, Cobb angle between 70° and 90° and posterior surgery only. He was able to identify 19 patients whose thoracic curves were measured between 70° and 90°. Out of these, four had convex-side bending Cobb angle values of less than 45° and were not included in the study, as they were judged too flexible. Fifteen patients (aged 11–18 years, mean 13.6 years) with thoracic scoliosis were left for the study (average Cobb angles 78.5° with a flexibility index of 32.5% (range, 19–42%). The mean follow-up period was 32 months (range 18–64 months). Classic parameters of deformity correction were analysed. The average operative time was 314 min and the mean total blood loss was 1,875 ml. Average level of instrumented vertebrae was 12 (Range, 10–14). Postoperatively, the thoracic Cobb angle was measured at 34.8° (range, 25–45°), which represents a correction rate of 54% (range, 40.0–67.1%) and remained unchanged at the last follow-up (35°). Patients with thoracic hypokyphosis improved from an average 11° to 18°. There were three complications (one excessive bleeding, one early infection and one late infection). One case showed an add-on phenomenon at the last follow-up. Coronal balance was improved from 1.8 cm (Range 0–4cm) down to 0.75 cm (range 0–2.5 cm). Shoulder balance was improved from 1.3 cm (range 0–4cm) down to 0.75 (0–2.5 cm). All patients reported satisfactory results except the patient with an adding-on phenomena. In the literature, most of the results of anterior thoracoscopic release and posterior surgery give a percentage of Cobb angle correction similar or inferior to our series for an average initial Cobb angle of less magnitude. Therefore, with adequate posterior release, and the use of third-generation segmental instrumentation there is no need for anterior release even for curves in the 70 –90° range.