Alignment In Adolescent Idiopathic Scoliosis Research Articles

Surgical Treatment of Adolescent Idiopathic Scoliosis with the ApiFix Minimal Invasive Dynamic Correction System-A Preliminary Report of a 24-Month Follow-Up.

Adolescent idiopathic scoliosis (AIS) is a three-dimensional growth disorder. Corrective surgical procedures are the recommended treatment option for a thoracic angle exceeding 50° and a lumbar major curve of 40°. Over the past few years, dynamic growth modulation implants have been developed as alternatives to permanent fusion. The ApiFix system was designed as a 2D "posterior dynamic device" for curve correction. After implantation in a minimally invasive procedure, it uses polyaxial joints and a self-adjusting rod to preserve the degree of motion and to accommodate the patient's growth. It provides an effective method of controlling deformity and fills the gap between the conservative treatment of major curves that are >35° and the fusion procedure. The objective of the two-center cohort study was the analysis of the correction results of patients, who underwent surgical intervention with the ApiFix system. The inclusion criteria were AIS, Lenke type 1 or type 5, a major curve on bending films of ≤30°, and an angle of the major curve of between 35° and 60°. Postoperative radiograph data were obtained longitudinally for up to 24 months of follow-up and compared to preoperative (preop) values. For comparisons of the different time points, non-parametric tests (Wilcoxon) or paired t-tests for normally distributed values were used to analyze repeated measures. Overall, 36 patients (25 female and 11 male) were treated with the ApiFix system from April 2018 to October 2020. Lenke type 1 was identified in 21 (58%) cases and Lenke type 5 was identified in 15 (42%) cases. The average angle of the thoracic major curve for Lenke 1 was 43°. The preoperative lumbar major curve (Lenke 5) was determined to be 43°. Over a follow-up of 24 months, a correction of the major curve to an average of 20° was observed for Lenke 1 and that to an average of 15° was observed for Lenke 5. Lenke type 1 and type 5 showed significant changes in the major curve over the individual test intervals in the paired comparisons compared to the starting angle (Lenke 1: preop-24 months, 0.002; Lenke 5: preop-24 months, 0.043). Overall, 11 events were recorded in the follow-up period, that required revision surgery. We distinguished between repeated interventions required after reaching the maximum distraction length of the implant due to the continued growth of the patient (n = 4) and complications, such as infections or problems associated with the anchorage of the implant (n = 7). The results from the present cohort revealed a statistically significant improvement in the postoperatively measured angles of the major and minor curves in the follow-up after 24 months. Consequently, the results were comparable to those of the already established vertebral body tethering method. Alignment in AIS via dynamic correction systems in combination with a possible growth modulation has been a treatment alternative to surgical fusing procedures for more than a decade. However, the long-term corrective effect has to be validated in further studies.

Do the three-dimensional parameters of brace-wearing patients with AIS change when transitioning from standing to sitting position? A preliminary study on Lenke I

BackgroundBracing is the most common conservative treatment for preventing the progression of adolescent idiopathic scoliosis (AIS) in patients with a curve of 25°–40°. X-ray examinations are traditionally performed in the standing position. However, school-age teenagers may take more time to sit. Thus far, little is known about three-dimensional (3D) correction in the sitting position. Hence, this study aimed to determine the effects of standing and sitting positions on 3D parameters during brace correction.MethodsWe evaluated a single-center cohort of patients receiving conservative treatment for thoracic curvature (32 patients with AIS with a Lenke I curve). The 3D parameters of their standing and sitting positions were analyzed using the EOS imaging system during their first visit and after bracing.ResultsAt the patients’ first visit, sagittal plane parameters such as thoracic kyphosis (TK), lumbar lordosis (LL), and sacral slope decreased when transitioning from the standing position to the sitting position (standing 29° ± 6°, 42° ± 8°, and 42° ± 8° vs. sitting 22° ± 5°, 27° ± 6°, and 24° ± 4°; p < 0.001), whereas pelvic tilt (PT) increased and sagittal vertical axis shifted forward (standing 9° ± 6° and 1.6 ± 2.7 cm vs. sitting 24° ± 4° and 3.8 ± 2.3 cm; p < 0.001). After bracing, TK and LL decreased slightly (from 29° ± 6° and 42° ± 8° to 23° ± 3° and 38° ± 6°; p < 0.001), whereas the thoracolumbar junction (TLJ) value increased (from 3° ± 3° to 11° ± 3°; p < 0.001). When transitioning to the sitting position, similar characteristics were observed during the first visit, except for a subtle increase in the TLJ and PT values (standing 11° ± 3° and 9° ± 4° vs. sitting 14° ± 3° and 28° ± 4°; p < 0.001). Moreover, the coronal and axial parameters at different positions measured at the same time showed no significant change.ConclusionsIn brace-wearing patients with thoracic scoliosis, compensatory sagittal plane straightening may be observed with a slight increase in thoracolumbar kyphosis, particularly when transitioning from the standing position to the sitting position, due to posterior rotation of the pelvis. Our results highlight that sagittal alignment in AIS with brace treatment is not completely analyzed with only standing X-Ray.Trial registrationThe study protocol was registered with the Chinese Clinical Trial Registry (ChiCTR1800018310).

Global sagittal alignment after surgery of right thoracic idiopathic scoliosis in adolescents and adults with and without thoracic hypokyphosis

This study aimed to characterize global sagittal alignment in adolescent idiopathic scoliosis (AIS) with normal kyphosis (NTK, kyphosis > 10°) and with thoracic hypokyphosis (THK, kyphosis < 10°), before and after posterior spinal fusion, and compare them with asymptomatic controls. 27 AIS girls and young adults with right thoracic curves were included (seventeen with age ≤ 18 years, then age > 21). Biplanar radiographies were acquired at baseline, immediate post-operatively, 1-year and 2-year follow-up, and 3D reconstruction of the spine and pelvis was performed. NTK and THK showed different global sagittal alignment, as well as differences compared to controls. AIS with THK at baseline had higher SVA/SFD (2.0 ± 2.9 vs − 0.4 ± 1.9; P < 0.05) and OD-HA (0.2 ± 1.4° vs − 1.3 ± 1.6°; P < 0.05) than controls, indicating that THK had compensated balance with unusual forward leaning posture. Immediately post-operation, SVA/SFD remained high (1.3 ± 3.0) while OD-HA reversed (− 1.2 ± 1.7°), indicating that THK patients had found partially compensated balance. After 2-yeas, both SVA/SFD (− 1.3 ± 2.1) and OD-HA (− 1.4 ± 0.9°) were normalized. The changes in global sagittal alignment and mechanism of balance are different in AIS with or without THK. As the head plays a critical role on balance during immediate and delayed post-operation, OD-HA can be complementary parameter for assessing global balance during post-operative follow-up of AIS patients with THK.

Comparative Study of the Spinopelvic Alignment in Patients With Idiopathic Lumbar Scoliosis Between Adulthood and Adolescence

Understanding the natural history of the spinopelvic alignment in adolescent idiopathic scoliosis (AIS) is important in developing surgical strategies for patients with adult idiopathic lumbar scoliosis (AdLS). Because it is challenging to follow individuals without any treatments, we sought to estimate its natural history by comparing radiographic characteristics of patients with AIS and AdLS. We included patients with Lenke 5 AIS and patients with AdLS who were diagnosed with Lenke 5 AIS in adolescence. The Cobb angle of the curve and spinopelvic parameters were measured by whole spine radiographs. The AdLS patients were divided into 2 groups according to age <50 years (AdLS<50) or ≥50 years (AdLS≥50). Radiographic parameters were compared among the AIS, AdLS<50, and AdLS≥50 groups. The relationship between age and each parameter was analyzed using nonlinear regression analysis. We analyzed 40 patients with AIS (all female, mean age 16.8 ± 3.2 years) and 35 patients with AdLS (34 female and 1 male, mean age 55.4 ± 12.1 years). Thoracolumbar/lumbar curve and thoracolumbar kyphosis was significantly greater in the AdLS<50 group compared with the AIS group, without progression after age 50 years. Lumbar lordosis and pelvic tilt deteriorated linearly with age. AIS and AdLS<50 patients maintained sagittal balance, which deteriorated in AdLS≥50 patients. Our results may predict the following natural course of Lenke 5 AIS: (1) progression of scoliotic deformity of thoracolumbar/lumbar curve with increased thoracolumbar kyphosis; (2) subsequent lumbar hypolordosis followed by pelvic retroversion; and (3) sagittal imbalance after failure of compensation.

The Correlation Between Postoperative Cervical Sagittal Alignment and Spine Sagittal Alignment in Adolescent Idiopathic Scoliosis: A Meta-Analysis

To perform a meta-analysis exploring the correlation between cervical lordosis (CL) and sagittal spine alignment in patients with adolescent idiopathic scoliosis (AIS) after surgery for determining a surgical strategy. We searched 3 electronic databases for studies discussing the correlation between CL and spine sagittal alignment in patients with AIS. Studies reported from the inception of the database to June 2019 were retrieved without any language restrictions. Summary correlation coefficient (r) values were extracted from each study, and 95% confidence intervals (CIs) were calculated. In addition, we conducted subgroup analyses in different curve type subgroups with at least 2 studies. Ten relevant studies involving 539 patients were evaluated in this meta-analysis. The Pearson correlation (r) for CL and the T1 slope was -0.69; (95% CI, -0.79 to -0.54). The fixed-effects summary correlation between CL and thoracic kyphosis in patients was moderate (r= -0.40; 95% CI, -0.48 to -0.31). In addition, the fixed-effects summary correlations between CL and lumbar lordosis (r= 0.19; 95% CI, 0.07-0.30), pelvic incidence (r= -0.08; 95% CI, -0.20 to 0.04), pelvic tilt (r= -0.06; 95% CI, -0.18 to 0.06), and sacral slope (r= -0.06; 95% CI, -0.18 to 0.06) in patients were weak. There is a strong negative correlation between CL and the T1 slope in patients with AIS. Given the lack of robust clinical evidence, these findings warrant verification by large prospective registries and randomized trials with long follow-up periods.

Three-dimensional pelvic incidence is much higher in (thoraco)lumbar scoliosis than in controls

PurposeThe pelvic incidence (PI) is used to describe the sagittal spino-pelvic alignment. In previous studies, radiographs were used, leading to less accuracy in establishing the three-dimensional (3D) spino-pelvic parameters. The purpose of this study is to analyze the differences in the 3D sagittal spino-pelvic alignment in adolescent idiopathic scoliosis (AIS) subjects and non-scoliotic controls.MethodsThirty-seven female AIS patients that underwent preoperative supine low-dose computed tomography imaging of the spine, hips and pelvis as part of their general workup were included and compared to 44 non-scoliotic age-matched female controls. A previously validated computerized method was used to measure the PI in 3D, as the angle between the line orthogonal to the inclination of the sacral endplate and the line connecting the center of the sacral endplate with the hip axis.ResultsThe PI was on average 46.8° ± 12.4° in AIS patients and 41.3° ± 11.4° in controls (p = 0.025), with a higher PI in Lenke type 5 curves (50.6° ± 16.2°) as compared to controls (p = 0.042), whereas the Lenke type 1 curves (45.9° ± 12.2°) did not differ from controls (p = 0.141).ConclusionLenke type 5 curves show a significantly higher PI than controls, whereas the Lenke type 1 curves did not differ from controls. This suggests a role of pelvic morphology and spino-pelvic alignment in the pathogenesis of idiopathic scoliosis. Further longitudinal studies should explore the exact role of the PI in the initiation and progression of different AIS types.Graphical abstractThese slides can be retrieved under Electronic Supplementary Material.

Sagittal balance and idiopathic scoliosis: does final sagittal alignment influence outcomes, degeneration rate or failure rate?

In the last decade, spine surgeons have been impacted by the "sagittal plane analysis revolution". Significant correlations have been found in adult spinal deformity (ASD) between sagittal lumbo-pelvic parameters and functional outcomes, but most of them do not apply in adolescent idiopathic scoliosis (AIS). Meanwhile, instrumentation and reduction strategies have considerably evolved. This paper aims to describe the preoperative sagittal alignment in AIS, and to report literature evidence regarding the influence of postoperative sagittal balance on complication rates, low back pain incidence and disc degeneration. A bibliographic search in Medline and Google database from 1984 to May 2017 was performed. The keywords included 'adolescent idiopathic scoliosis', 'adult scoliosis', 'sagittal alignment', 'proximal junctional kyphosis', 'distal junctional kyphosis', 'outcomes', 'low back pain' and 'complication', used individually or in combination. Algorithms of sagittal balance analysis and treatment decision have been reported in ASD, but the clinical situation is very different in children. Sagittal alignment greatly varies in AIS among the various Lenke types. Most patients are clinically balanced before surgery, but the spinal harmony is altered, with overgrowth of the anterior column and global sagittal flattening (undersestimated in 2D). The exact role of pelvic incidence and whether or not patients also use pelvic compensation to maintain balance still require further clarification. The incidence of radiological junctional failures remains highly variable, depending on definitions, cohort size and follow-up. Preoperative hyperkyphosis seems to be a consistent and relevant risk factor. Current literature does not support the recent trend to save motion segments (selective fusion), and no significant association was found between the distal level of fusion and the incidence of low back pain. Postoperative sagittal alignment seems to be more important than LIV selection to avoid disc degeneration at mid-term follow-up. It is clear now that sagittal alignment plays a major role in clinical outcomes and should not be neglected in AIS. Seven key guidelines that should be considered for each patient before surgery are reported (Table2). Personalized planning using 3D technology is gaining popularity and might help in the future reducing complications.

Normal Age-Adjusted Sagittal Spinal Alignment Is Achieved with Surgical Correction in Adolescent Idiopathic Scoliosis.

Study DesignRetrospective analysis.PurposeOur hypothesis is that the surgical correction of adolescent idiopathic scoliosis (AIS) maintains normal sagittal alignment as compared to age-matched normative adolescent population.Overview of LiteratureSagittal spino-pelvic alignment in AIS has been reported, however, whether corrective spinal fusion surgery re-establishes normal alignment remains unverified.MethodsSagittal profiles and spino-pelvic parameters of thirty-eight postsurgical correction AIS patients ≤21 years old without prior fusion from a single institution database were compared to previously published normative age-matched data. Coronal and sagittal measurements including structural coronal Cobb angle, pelvic incidence, pelvic tilt, thoracic kyphosis, lumbar lordosis, sagittal vertical axis, C2–C7 cervical lordosis, C2–C7 sagittal vertical axis, and T1 pelvic angles were measured on standing full-body stereoradiographs using validated software to compare preoperative and 6 months postoperative changes with previously published adolescent norms. A sub-group analysis of patients with type 1 Lenke curves was performed comparing preoperative to postoperative alignment and also comparing this with previously published normative values.ResultsThe mean coronal curve of the 38 AIS patients (mean age, 16±2.2 years; 76.3% female) was corrected from 53.6° to 9.6° (80.9%, p<0.01). None of the thoracic and spino-pelvic sagittal parameters changed significantly after surgery in previously hypo- and normo-kyphotic patients. In hyper-kyphotic patients, thoracic kyphosis decreased (p=0.003) with a reciprocal decrease in lumbar lordosis (p=0.01), thus lowering pelvic incidence-lumbar lordosis mismatch mismatch (p=0.009). Structural thoracic scoliosis patients had slightly more thoracic kyphosis than age-matched patients at baseline and surgical correction of the coronal plane of their scoliosis preserved normal sagittal alignment postoperatively. A sub-analysis of Lenke curve type 1 patients (n=24) demonstrated no statistically significant changes in the sagittal alignment postoperatively despite adequate coronal correction.ConclusionsSurgical correction of the coronal plane in AIS patients preserves sagittal and spino-pelvic alignment as compared to age-matched asymptomatic adolescents.

73 - Interpreting 2-Dimensional and 3-Dimensional Alignment in Adolescent Idiopathic Scoliosis—How Should Thoracic Kyphosis be Defined?

BACKGROUND CONTEXT: Adolescent idiopathic scoliosis (AIS) is often associated with thoracic apical hypokyphosis. By nomenclature, thoracic kyphosis (TK) is measured as the difference in tilt between T1-T12, but does not consider the shape of the thoracic apex. Previous studies have described coronal and sagittal alignment using 2-dimensional (2D) radiographs, which may not project orthogonal to the true plane of TK, nor account for the difference between apical and overall TK. The advent of 3-dimensional (3D) imaging has redefined the concept of measurement of TK and by utilizing these 3D reconstructions, our study found that while T1-T12 tilt increased perioperatively, true kyphosis, as measured at the thoracic apex, decreased.

Upright, prone, and supine spinal morphology and alignment in adolescent idiopathic scoliosis

BackgroundPatients with adolescent idiopathic scoliosis (AIS) are usually investigated by serial imaging studies during the course of treatment, some imaging involves ionizing radiation, and the radiation doses are cumulative. Few studies have addressed the correlation of spinal deformity captured by these different imaging modalities, for which patient positioning are different. To the best of our knowledge, this is the first study to compare the coronal, axial, and sagittal morphology of the scoliotic spine in three different body positions (upright, prone, and supine) and between three different imaging modalities (X-ray, CT, and MRI).MethodsSixty-two AIS patients scheduled for scoliosis surgery, and having undergone standard pre-operative work-up, were included. This work-up included upright full-spine radiographs, supine bending radiographs, supine MRI, and prone CT as is the routine in one of our institutions. In all three positions, Cobb angles, thoracic kyphosis (TK), lumbar lordosis (LL), and vertebral rotation were determined. The relationship among three positions (upright X-ray, prone CT, and supine MRI) was investigated according to the Bland-Altman test, whereas the correlation was described by the intraclass correlation coefficient (ICC).ResultsThoracic and lumbar Cobb angles correlated significantly between conventional radiographs (68° ± 15° and 44° ± 17°), prone CT (54° ± 15° and 33° ± 15°), and supine MRI (57° ± 14° and 35° ± 16°; ICC ≥0.96; P < 0.001). The thoracic and lumbar apical vertebral rotation showed a good correlation among three positions (upright, 22° ± 12° and 11° ± 13°; prone, 20° ± 9° and 8° ± 11°; supine, 16° ± 11° and 6° ± 14°; ICC ≥0.82; P < 0.001). The TK and LL correlated well among three different positions (TK 26° ± 11°, 22° ± 12°, and 17° ± 10°; P ≤ 0.004; LL 49° ± 12°, 45° ± 11°, and 44° ± 12°; P < 0.006; ICC 0.87 and 0.85).ConclusionsAlthough there is a generalized underestimation of morphological parameters of the scoliotic deformity in the supine and prone positions as compared to the upright position, a significant correlation of these parameters is still evident among different body positions by different imaging modalities. Findings of this study suggest that severity of scoliotic deformity in AIS patients can be largely represented by different imaging modalities despite the difference in body positioning.

Relationship between cervical sagittal alignment and health-related quality of life in adolescent idiopathic scoliosis.

Little information is available on the relationship between cervical sagittal alignment and health-related quality of life (HRQOL) in adolescent idiopathic scoliosis (AIS) patients. The aim of this study was to identify relationships between postoperative cervical sagittal alignment and HRQOL in AIS. The study and control groups comprised 67 AIS patients (51 girls and 16 boys). All underwent anteroposterior and lateral plain radiography and completed clinical questionnaires. The radiographic parameters investigated were pre- and postoperative C2-C7 lordosis, C2-C7 sagittal vertical axis (SVA), T1 slope, T1 slope minus C2-C7 lordosis (TS-CL), thoracic kyphosis (TK), lumbar lordosis (LL), pelvic tilt (PT), sacral slope (SS), and pelvic incidence (PI). The Korean version of the SRS-22 questionnaire and the previously validated Short Form-36 (SF-36) outcome questionnaire were administered to evaluate HRQOL at last follow-up visits. Statistical analysis was performed to determine the significances of differences between preoperative and last follow-up radiological findings. In addition, correlations between radiological parameters and clinical questionnaire scores were sought. Radiological sagittal parameters were found to be significantly increased after surgical correction in terms of C2-C7 lordosis (3.5±11.4), C2-C7 SVA (1.5±6.0), T1 slope (3.5±6.1), and TK (6.0±8.1). However, no significant difference was observed for TS-CL, LL, PT, SS, and PI (P>0.05). Correlation analysis revealed significant relationships between radiographic parameters and questionnaire scores. Multiple regression analysis was performed to identify predictors of HRQOL, and the results obtained revealed that postoperative T1 slope significantly predicted SRS, PCS, and MCS scores and that postoperative C2-C7 SVA predicted SRS scores. Changes in cervical sagittal parameters were significant after deformity correction in AIS patients. Correlation analysis revealed significant relationships between postoperative radiographic parameters and HRQOL. In particular, T1 slope and C2-C7 SVA were found to be significant predictors of HRQOL in AIS patient.

Interest of T1 parameters for sagittal alignment evaluation of adolescent idiopathic scoliosis patients.

In the last few years several reports stressed the importance of sagittal alignment in adolescent idiopathic scoliosis (AIS) patients. It was recently reported that T1 slope, defined as the angle between the superior endplate of T1 and the horizontal, correlates strongly with overall sagittal parameters. The aim of this study was to assess the impact of T1 parameters (T1-slope and T1-tilt) on sagittal alignment of AIS hypokyphotic patients preoperatively and postoperatively. Twenty-nine AIS patients with <20° preoperative hypokyphosis were included in a retrospective study. Surgery systematically comprised hybrid construct with screws below T11, sublaminar bands at thoracic level and a lamino-laminar claw on the upper instrumented vertebra. Preoperative, postoperative and 2-year follow-up radiological assessment included Cobb angle, T1 slope, T1 sagittal tilt, regional sagittal parameters and pelvic parameters. In the series as a whole, coronal Cobb angle was significantly reduced postoperatively (58° vs. 17°; p < 0.001), thoracic kyphosis significantly improved (12.4° vs. 25.6°; p < 0.001) and cervical lordosis significantly restored (6.2° kyphosis vs. 4.1° lordosis; p < 0.001). There was a significant modification in T1-slope (10.2° vs. 18.2°; p < 0.001). Preoperatively, T1 slope was significantly correlated with T1 tilt (r = 0.427; p = 0.029). Postoperatively, T1 slope was significantly correlated with T1 tilt (r = 0.549; p = 0.002), thoracic kyphosis (r = 0.535, p = 0.005) and cervical lordosis (r = -0.444, p = 0.03). Restoration of cervical lordosis was significantly correlated to changes of T1-slope (r = -0.393, p = 0.032), which was significantly correlated to postoperative thoracic kyphosis. According to these results, T1 seems to be of major interest in postoperative modifications of sagittal alignment. T1 slope and sagittal tilt are good indicators of postoperative changes for regional (cervical lordosis and thoracic kyphosis) and global parameters. We therefore consider these parameters as essential in the assessment of AIS patients. Further studies and correlation with clinical scores will, however, be necessary in order to confirm the present findings.

Long-term effects of the Chêneau brace on coronal and sagittal alignment in adolescent idiopathic scoliosis.

The aim of the present study was to retrospectively evaluate progressive correction of coronal and sagittal alignment and pelvic parameters in patients treated with a Chêneau brace. Thirty-two patients with adolescent idiopathic scoliosis (AIS) were assessed before initiation of bracing treatment and at the final follow-up. Each patient underwent radiological examinations, and coronal, sagittal, and pelvic parameters were measured. No statistically significant modification of the Cobb angle was noted. The pelvic incidence remained unchanged in 59% of the cases and increased in 28% of the cases. The sacral slope decreased in 34% of the cases but remained unchanged in 50%. Thoracic kyphosis and lumbar lordosis were significantly decreased, whereas the sagittal vertical axis was significantly increased from a mean of -44.0 to -30.2 mm (p = 0.02). The mean pelvic tilt increased significantly from 4.5° to 8.3° (p = 0.002). The Chêneau brace can be useful for preventing curvature progression in patients with AIS. However, the results of this study reveal high variability in the effect of brace treatment on sagittal and pelvic alignment. Treatment with the Chêneau brace may also influence sagittal global balance.

Three-Dimensional Spinopelvic Relative Alignment in Adolescent Idiopathic Scoliosis

Three-dimensional (3D) analysis of the spinopelvic alignment in adolescent idiopathic scoliosis (AIS). To study the 3D pelvic alignment with respect to the spinal deformities in AIS subgroups. Spinopelvic alignment is subject to change in scoliosis. Many sacropelvic parameters were developed to characterize spinopelvic alignment in the sagittal plane. However, not much is known about the 3D pelvic alignment with respect to the thoracic and lumbar spinal deformities in AIS. Eighty AIS subjects with right main thoracic (MT), 80 AIS with left thoracolumbar/lumbar (TL/L) curves, and 35 asymptomatic controls were included. Thoracic and lumbar Cobb angles, kyphosis, lordosis, pelvic incidence, pelvic tilt, and sacral slope were measured. Pelvic tilt and axial rotation in the coronal and transverse planes, respectively, were computed using the ipsilateral anterior superior iliac spine and posterior superior iliac spine positions. Leg length discrepancy was determined by the vertical difference in the position of the center of the femoral heads in the coronal plane. In 59% of the MT subjects and 79% of the TL/L subjects in the erect position, the pelvis was tilted toward the convex side of the major curve in the coronal plane. The direction of the pelvic axial rotation in the transverse plane was in the same direction as the MT apical vertebra rotation in 84% of the MT subjects and 55% of the TL/L group. The pelvic incidence correlated to the lumbar lordosis in AIS (r = 0.41, P < 0.001). Pelvic coronal tilt correlated significantly to the leg length discrepancy in MT (r = 0.67) and TL/L (r = 0.61) subjects (P < 0.001). Novel pelvic parameters were introduced to characterize the spinopelvic relative alignment in scoliotic subgroups. The proposed method related the orientation of the pelvis in the coronal and transverse planes to both thoracic and lumbar spinal deformities.

Sagittal Cervical Alignment in Adolescent Idiopathic Scoliosis

Study DesignRetrospective case series of surgically treated adolescent scoliosis patients. ObjectivesTo assess the radiographic changes of cervical kyphosis and identify the possible factors affecting postoperative sagittal cervical kyphosis in surgically treated patients with adolescent idiopathic scoliosis. Summary of Background DataCervical kyphosis is a well-recognized phenomenon in patients with adolescent idiopathic scoliosis. Despite recent reports, the prevalence, radiographic changes, and possible factors affecting postoperative sagittal cervical kyphosis are controversial. Materials and MethodsA retrospective review of a single-center database was performed on 133 consecutive patients with adolescent idiopathic scoliosis treated with long instrumented (more than 5 levels) spine fusion (minimum, 2 years; mean, 3.3 years; range, 2 to 5.5 years). A total of 89 patients met all of the inclusion criteria. Preoperative and postoperative radiographic measurements and patient demographics were investigated. ResultsPostoperative cervical kyphosis was observed in 46 patients. Cobb angle decreased from 48.1° ± 13.1° to 15.4° ± 11.1° at the final follow-up. Cervical kyphosis significantly decreased from 5.5° ± 8.9° preoperatively to −1.5° ± 8.9° at the final follow-up. No difference was observed for T2–T5, T5–T12, lumbar lordosis, sacral slope, pelvic incidence, pelvic tilt, and sagittal vertical axis during the follow-up. Notably, T2 sagittal tilt was significantly increased from preoperatively to the final follow-up. Pearson correlation coefficient test showed a strong correlation between postoperative cervical lordosis and T2 sagittal tilt (r = 0.73; p < .001). ConclusionsDespite the significant increase of cervical lordosis, 85% of patients still have a kyphotic or less lordotic cervical spine. The strong positive association between cervical lordosis and T2 sagittal tilt suggests that the sagittal cervical alignment of adolescent idiopathic scoliosis patients is closely related to the global sagittal spine balance rather than thoracic kyphosis.

Spinal alignment in surgical, multisegmental, transpedicular correction of adolescent idiopathic scoliosis

SummaryThe objective of this study was to discuss the variables influencing alignment mechanisms of the spine, with particular consideration of post-surgical alignment in adolescent idiopathic scoliosis. The analysis is based on information currently available in the literature, and on the authors’ own experience, which includes surgical material from over 2200 cases of idiopathic scoliosis.Over 50% of cases of adolescent idiopathic scoliosis are decompensated before surgical treatment. Spinal alignment is most significantly influenced by the position of the pelvis. Surgical restoration of lumbar lordosis is more important than attempting to restore thoracic kyphosis in the sagittal plane. The sagittal profile has an essential impact on spinal alignment. The same curves in the coronal plane can have various 3-dimensional configurations. Clinical difficulties in the assessment of thoracic kyphosis and lumbar lordosis result from the fact that they undergo constant change with age. Thoracic hypokyphosis diagnosed before surgery is a very frequent symptom of curve progression. The presence of proximal (thoraco-thoracic) and distal (thoraco-lumbar) junctional kyphosis is very important for planning the scope of spondylodesis.The natural tendency of the spine for alignment (compensation) after surgery nowadays occurs more naturally by applying derotational forces through pedicle screws, compared to the distraction devices (eg, Harrington rod) used in the past.

Three-Dimensional Analysis of Thoracic Apical Sagittal Alignment in Adolescent Idiopathic Scoliosis

Retrospective review of a series of adolescent idiopathic scoliosis patients. To perform a 3-dimensional (3D) analysis of patients with thoracic scoliosis to identify differences in the thoracic sagittal alignment measured from the standard lateral projection as compared to the "true lateral" view. It has been difficult to clinically obtain radiographs in the planes of maximum spinal deformity. Recently, 3D models of the spine have been developed using biplanar radiographic reconstructions that allow a more accurate assessment of spinal alignment. Three-dimensional spinal reconstructions using biplanar radiographs were used to evaluate the apical thoracic sagittal profile. A measurement of sagittal curvature from 2 vertebral levels above and below the thoracic apex (5 vertebrae) was recorded from the standard lateral view. The 3D reconstructions were then rotated to achieve a "true lateral" view of the apical thoracic vertebra and the sagittal apical curvature was remeasured. The difference in the 2 measures of sagittal thoracic apical alignment was compared using repeated measures ANOVA, and then correlated to the coronal thoracic Cobb magnitude using a Pearson correlation analysis (P < 0.05). Sixty-six adolescent idiopathic scoliosis patients with right thoracic scoliosis (Cobb averaged 47 degrees +/- 10 degrees ) were evaluated. The apical thoracic sagittal curvature in the standard lateral view averaged 11 degrees +/- 10 degrees of kyphosis (range: -8 degrees to 38 degrees ). This was statistically greater (P < 0.001) than the apical sagittal curvature in the "true lateral" view that averaged 1 degrees +/- 9 degrees (range:-23 degrees to 22 degrees ). The standard lateral view was rotated an average of 13 degrees +/- 4 degrees to achieve the ideal lateral view of the thoracic apex. This 3D analysis of thoracic scoliosis demonstrated a consistent loss of kyphosis within the 5 thoracic apical vertebrae. The true apical sagittal profile was found to be overestimated by an average of 10 degrees as compared to the perceived alignment from standard lateral radiographs.

Thoracoscopic anterior instrumented fusion for adolescent idiopathic scoliosis with emphasis on the sagittal plane

Background context Anterior fusion through an open thoracotomy restores kyphosis more reliably than posterior techniques in patients with thoracic adolescent idiopathic scoliosis (AIS). Video-assisted thoracoscopic spinal fusion and instrumentation (VATS) minimizes the morbidity, from soft tissue and muscle dissection that accompanies traditional open thoracotomy. To our knowledge, there has not been a comprehensive analysis of VATS with respect to radiographic and clinical outcomes in the sagittal plane. Purpose To measure the radiographic and clinical outcomes after VATS with emphasis on the sagittal plane. Study design/setting A retrospective, radiographic review of 26 consecutive patients with Lenke type-I AIS who underwent VATS. Methods Radiographs of 26 consecutive patients with Lenke type-I AIS curves operated by a single surgeon were retrospectively reviewed after VATS. Sagittal and coronal parameters were compared with reported data for open anterior and posterior procedures. Results There was an increase in kyphosis from baseline to final follow-up by 6.6° (25%) from T2 to T12 (p<.0001), 8.7° (50%) from T5 to T12 (p<.0001), and 8° (54%) in the instrumented segment (p<.0001). Junctional kyphosis did not occur. No differences were detected in sagittal measurements between the first postoperative erect and the final radiographs. Patients experienced significant improvements from baseline to 2 years in Scoliosis Research Society-22 Health-Related Quality-of-Life Outcome Questionnaire scores (p<.0001). Conclusions Video-assisted thoracoscopic spinal fusion and instrumentation, in agreement with results reported for open anterior instrumentation, reliably restores or increases thoracic kyphosis while preserving junctional alignment in thoracic AIS.

The Use of Multiple Anchors for the Treatment of Idiopathic Scoliosis

Retrospective study. The purpose of this study was to determine the effectiveness of concave collar-button wires used as anchors to correct and maintain spinal alignment in adolescent idiopathic scoliosis (AIS). Correction of idiopathic scoliotic deformity has been reported with various systems. We have added concave collar-button wires to a multihook, dual-rod system as an adjunct to translation and stabilization of the spine during correction of AIS. Sixty-seven patients failing brace treatment or with curve patterns >45 degrees underwent spinal correction. Evaluation was obtained with preoperative standing posteroanterior, lateral, and recumbent right and left bending radiographs using the Cobb method. The initial postoperative films and latest radiographs were measured also. A dual-rod multihook construct with a derotation maneuver was used in all cases. Collar-button wire implants were placed from the convex side of the deformity toward the concave rod through the base of the spinous processes within the construct to achieve and augment correction and stability. Twenty-four patients underwent prior anterior release and fusion by video assisted thoracoscopic surgery. Sixty-seven patients in total underwent this procedure. We achieved a 72.2% mean correction of thoracic curves and 63.2% mean correction of lumbar curves. There was a mean loss of correction of 2 degrees in the thoracic area and 2.2 degrees in the lumbar area after 2 years. Sagittal curve was unchanged after surgery. All patients demonstrated a solid fusion with no evidence of pseudarthrosis or junctional deformities. There were no cases of clinically significant wire breakage or hook pullout. Three delayed infections were noted. The use of multiple concave collar-button wires as anchors is a safe, easy, and reliable method of spinal stabilization in the coronal and sagittal planes. There is minimal loss of correction at long-term follow-up.

Sagittal plane analysis of the spine and pelvis in adolescent idiopathic scoliosis according to the coronal curve type.

A retrospective study investigated the sagittal alignment in adolescent idiopathic scoliosis (AIS). To evaluate the sagittal alignment of the spine and pelvis in adolescent idiopathic scoliosis on the basis of curve type. The relation between the spine and pelvis highly influences the sagittal balance in adults. However, the sagittal alignment of the spine and pelvis in adolescent idiopathic scoliosis is poorly defined in the literature. Five sagittal parameters were evaluated on lateral radiographs of 160 patients with adolescent idiopathic scoliosis: thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and pelvic incidence. The patients were classified according to their coronal curve type. Analysis of variance was used to compare the parameters between the curve types, and Pearson coefficients were used to investigate the relation between all parameters (alpha = 0.05). The thoracic kyphosis was significantly lower for King I, II, and III curves than for lumbar curves. The lumbar lordosis was higher for lumbar curves, although not significantly. No significant change between the groups was observed for the sacral slope, pelvic tilt, or pelvic incidence. The pelvic incidence was significantly correlated with the lumbar lordosis, sacral slope, and pelvic tilt for all the groups. The lumbar lordosis was strongly related to the sacral slope in all cases, but not with the thoracic kyphosis, except in the case of thoracolumbar curves. Thoracic kyphosis depended mostly on the spinal deformity, whereas lumbar lordosis was influenced mainly by the pelvic configuration. The scoliotic curve type was not associated with a specific pattern of sagittal pelvic morphology and balance. The pelvic incidence found in this study was significantly higher than that reported in the literature for normal adolescents. The role of the pelvic incidence in the pathogenesis of adolescent idiopathic scoliosis needs to be explored in a longitudinal study involving patients with adolescent idiopathic scoliosis and normal adolescents.