Morphometric Analysis of the Thoracic Intervertebral Foramen Osseous Anatomy in Adolescent Idiopathic Scoliosis Using Low-Dose Computed Tomography

PURPOSE

The dimensions of the thoracic intervertebral foramen in adolescent idiopathic scoliosis (AIS) have not previously been quantified. Better understanding of the dimensions of the foramen may be useful in surgical planning. This study describes a reproducible method for measurement of the thoracic foramen in AIS using computed tomography (CT).

METHODS

In 23 preoperative female patients with Lenke 1 type AIS with right-side convexity major curves confined to the thoracic spine the foraminal height (FH), foraminal width (FW), pedicle to superior articular process distance (P-SAP), and cross-sectional foraminal area (FA) were measured using multiplanar reconstructed CT. Measurements were made at entrance, midpoint, and exit of the thoracic foramina from T1-T2 to T11-T12. Results were also correlated with dependent variables of major curve Cobb angle measured on X-ray and CT, age, weight, Lenke classification subtype, Risser grade, and number of spinal levels in the major curve.

RESULTS

The FH, FW, P-SAP, and FA dimensions and ratios are all significantly larger on the convexity of the major curve and maximal at or close to the apex. Mean thoracic foraminal dimensions change in a predictable manner relative to position on the major thoracic curve. There was no statistically significant correlation with the measured foraminal dimensions or ratios and the individual dependent variables. The average ratio of convexity to concavity dimensions at the apex foramina for entrance, midpoint, and exit, respectively, are FH (1.50, 1.38, 1.25), FW (1.28, 1.30, 0.98), FA (2.06, 1.84, 1.32), and P-SAP (1.61, 1.47, 1.30).

CONCLUSION

Foraminal dimensions of the thoracic spine are significantly affected by AIS. Foraminal dimensions have a predictable convexity-to-concavity ratio relative to the proximity to the major curve apex. Surgeons should be aware of these anatomical differences during scoliosis correction surgery.

Efficacy of tranexamic acid in reducing allogeneic blood products in adolescent idiopathic scoliosis surgery

BACKGROUND

Adolescent idiopathic scoliosis (AIS) surgery usually require prolonged operative times with extensive soft tissue dissection and significant perioperative blood loss, and allogeneic blood products are frequently needed. Methods to reduce the requirement for transfusion would have a beneficial effect on these patients. Although many previous studies have revealed the efficacy of tranexamic acid (TXA) in spinal surgery, there is still a lack of agreement concerning the reduction of both blood loss and transfusion requirements of large dose tranexamic acid (TXA) in surgery for adolescent idiopathic scoliosis (AIS). The objective of this study was to elevate the efficacy and safety of a large dose tranexamic acid (TXA) in reducing transfusion requirements of allogeneic blood products in adolescent idiopathic scoliosis (AIS) surgery using a retrospective study designed with historical control group.

METHODS

One hundred thirty seven consecutive AIS patients who underwent surgery treatment with posterior spinal pedicle systems from August 2011 to March 2015 in our scoliosis center were retrospectively reviewed. Patients were divided into two groups, the TXA group and the historical recruited no TXA group (NTXA). Preoperative demographics, radiographic parameters, operative parameters, estimated blood loss (EBL), total irrigation fluid, number of patients requiring blood transfusion, mean drop of Hb (Pre-op Hb-Post-op Hb), haematocrit pre and post-surgery, mean volume of blood transfusion, hospitalization time, and adverse effect were recorded and compared.

RESULTS

All the patients were successfully treated with satisfied clinical and radiographic outcomes. There were 71 patients in the TXA group and 66 patients in the NTXA group. The preoperative demographics were homogeneity between two groups (P > 0.05). There were no significant difference in average operative time between two groups (209 min vs 215 min, p >0.05). Number of patients in the TXA group showed a significant decrease in transfusion requirements with an associated reduced intraoperative blood loss of nearly 45% compared with those in NTXA group (8 vs 37, 619 ml vs 1125 ml, P < 0.05). There were no significant difference in total irrigation fluid between two groups (540 vs 550, p >0.05). Additional, patients in NTXA group showed significant decrease of Hb compared with patients in TXA group (5.2 g/dL vs 3.3 g/dL, P < 0.05), No significant difference were found in hospitalization time between two groups (6.3 vs 7.2 days, P > 0.05). No minor adverse effects associated with use of TXA were noted.

CONCLUSIONS

Use of large dose tranexamic acid routinely seems to be effective and safe in reducing allogenic blood transfusion and blood loss in adolescent idiopathic scoliosis surgery.

Validity Study of Vertebral Rotation Measurement Using 3-D Ultrasound in Adolescent Idiopathic Scoliosis

This study aimed to assess the validity of 3-D ultrasound measurements on the vertebral rotation of adolescent idiopathic scoliosis (AIS) under clinical settings. Thirty curves (mean Cobb angle: 21.7° ± 15.9°) from 16 patients with AIS were recruited. 3-D ultrasound and magnetic resonance imaging scans were performed at the supine position. Each of the two raters measured the apical vertebral rotation using the center of laminae (COL) method in the 3-D ultrasound images and the Aaro-Dahlborn method in the magnetic resonance images. The intra- and inter-reliability of the COL method was demonstrated by the intra-class correlation coefficient (ICC) (both [2, K] >0.9, p < 0.05). The COL method showed no significant difference (p < 0.05) compared with the Aaro-Dahlborn method. Furthermore, the agreement between these two methods was demonstrated by the Bland-Altman method, and high correlation was found (r > 0.9, p < 0.05). These results validated the proposed 3-D ultrasound method in the measurements of vertebral rotation in the patients with AIS.

Cervicocephalic relocation test to evaluate cervical proprioception in adolescent idiopathic scoliosis

PURPOSE

Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the spine associated with disturbed postural control. Cervical proprioception participates in controlling orthostatic posture via its influence on head stabilization. We hypothesized that patients with AIS exhibit altered cervical proprioception.

METHODS

We conducted a case-control study to evaluate cervical proprioception using the cervicocephalic relocation test (CRT) in 30 adolescents with AIS (15.5 ± 1.5 years; Cobb 24.8° ± 9.5°) versus 14 non-scoliotic controls (14.6 ± 2.0 years). CRT evaluates cervical proprioception by measuring the capacity to relocate the head on the trunk after active rotation of the head in the transversal plane without visual control. Each subject performed ten right and then ten left head rotations.

RESULTS

The CRT results were pathological in 12 AIS patients (40 %). The CRT mean was significantly different between AIS patients with a pathological CRT (5° ± 1.4° for right rotation; 4.2° ± 0.9° for left rotation) compared with AIS patients with a normal CRT (2.7° ± 0.6° for right rotation; 2.9° ± 0.8° for left rotation) or with the control group (3.5° ± 2.1° for right rotation; 3.1° ± 1.2° for left rotation).

CONCLUSION

Cervical proprioception is impaired in certain AIS patients. This anomaly may worsen the prognosis of AIS (headache; balance disorders; worsened spinal deformity; complication after spinal fusion). We recommend systematic screening for altered cervical proprioception in AIS patients.

Genomic study of adolescent idiopathic scoliosis in Japan

Adolescent idiopathic scoliosis (AIS) is a common disease. It is a multi-factorial (polygenic) disease controlled by genetic and environmental factors. Studies searching for genetic factors of AIS using linkage and association analyses have been conducted and several susceptibility genes have been reported. This paper reviews the recent progress in the genome-wide association study of AIS in Japan and comments on its future task.

Visual loss after corrective surgery for pediatric scoliosis: incidence and risk factors from a nationwide database

BACKGROUND CONTEXT

Perioperative visual loss (POVL) after spinal deformity surgery is an uncommon but severe complication. Data on the incidence and risk factors of this complication after corrective surgery in the pediatric population are limited.

PURPOSE

The present study aimed to investigate nationwide estimates of POVL after corrective surgery for pediatric scoliosis.

STUDY DESIGN

This is a retrospective study that uses a nationwide database.

PATIENT SAMPLE

The sample includes 42,339 patients under the age of 18 who underwent surgery for idiopathic scoliosis.

OUTCOME MEASURES

The outcome measures were incidence of POVL and risk factors.

METHODS

Patients under the age of 18 who underwent elective surgery for idiopathic scoliosis between 2002 and 2011 were identified using the Nationwide Inpatient Sample database. The incidence of POVL (ischemic optic neuropathy, central retinal artery occlusion, or cortical blindness) was estimated after application of discharge weights. Demographics, comorbidities, and operative parameters were compared between patients with and without visual loss. A multivariate logistic regression was performed to identify significant risk factors for POVL development. No funds were received in support of this work.

RESULTS

The incidence of POVL was 1.6 per 1,000 procedures (0.16%). Patients with visual loss were significantly more likely to be younger and male, have Medicaid as insurance, and undergo fusion of eight or more spinal levels compared with patients without visual loss. Following multivariate analysis, older patients (odds ratio [OR]: 0.84; 95% confidence interval [CI]: 0.77-0.91) and female patients (OR: 0.08; 95% CI: 0.04-0.14) were significantly less likely to develop POVL compared with younger and male patients. On the other hand, having Medicaid as insurance (OR: 2.13;95% CI: 1.32-3.45), history of deficiency anemia (OR: 8.64; 95% CI: 5.46-14.31), and fusion of eight or more spinal levels (OR: 2.40; 95% CI: 1.34-4.30) were all independently associated with POVL.

CONCLUSIONS

In this nationwide study, the incidence of POVL after scoliosis surgery in patients under the age of 18 was estimated at 0.16%, similar to the rate reported in adult patients. Cortical blindness accounted for all cases of POVL in the present study. Younger patients, patients with history of deficiency anemia, and patients undergoing long-segment fusions may be at increased risk of POVL after corrective surgery for pediatric scoliosis.

Complications After Surgical Treatment of Adolescent Idiopathic Scoliosis

Even with current techniques and instrumentation, complications can occur after operative treatment of adolescent idiopathic scoliosis. The most dreaded complications-neurologic deficits-are relatively infrequent, occurring in 1% or less of patients. Nonneurologic deficits, such as infection, pseudarthrosis, curve progression, and proximal junctional kyphosis, are more frequent, but are much less likely to require reoperation or to cause poor functional outcomes. Understanding the potential complications of surgical treatment of pediatric spinal deformity is essential for surgical decision-making.

Health-related quality of life of adolescents conservatively treated for idiopathic scoliosis in Korea: a cross-sectional study

Background

Young adolescents with scoliosis are more likely than adults to experience psychological distress affecting health-related quality of life (HRQoL). Adolescence is a sensitive period of psychological development, and thus physical deformity from scoliosis can negatively affect body image and appearance of adolescents. The present study evaluated HRQoL in young Korean adolescents with idiopathic scoliosis and identified related factors.

Methods

One hundred and ten adolescents with idiopathic scoliosis were recruited from two tertiary hospital outpatient clinics over one year. HRQoL was measured using the Korean version of the Scoliosis Research Society 22 revision (SRS-22r) questionnaire. In addition, participant medical records were reviewed to collect data on severity of scoliosis, type of treatment and age at which they were first diagnosed with the disease.

Results

The mean age of the participants was 14.2 years and 48.2 % were first diagnosed at 9–12 years. Most participants (61.8 %) were under observation to follow up the curvature progression and 20.9 % received regular physiotherapy. Almost half the participants (47.3 %) had mild (10°–25°), 41.8 % moderate (25°–40°), and 10.9 % severe (>40°) scoliosis. The total score of the SRS-22r differed significantly between the groups of age at diagnosis (p = 0.033) and type of treatment (p = 0.025). Self-image, a sub-domain of the SRS 22r, was significantly lower in the severe curve deformity group than in the other groups (p = 0.031).

Conclusions

An earlier age of scoliosis diagnosis and conservative treatment were related to higher HRQoL scores of Korean adolescents with scoliosis. Although the overall HRQoL did not significantly differ by severity of disease, self-image was significantly decreased in adolescents with severe spinal deformity. HRQoL of adolescent patients with idiopathic scoliosis can be affected by several factors that medical staff needs to consider in order to produce the best and most effective treatment outcomes.

Relationship between the different torsion-related thoracic deformity parameters of adolescent idiopathic scoliosis

INTRODUCTION

Torsion has recently become essential in curve evaluation, not only to assess the degree of clinical deformity that can influence decision making, but also to predict curve progression. Since torsion cannot be currently measured using plain X-rays, our aim was to study the relationships between the different torsion-related parameters measured on 2D radiographs that can indirectly guide the clinician about the torsion of a given curve.

METHODS

This is a cross-sectional study analyzing prospectively registered data of a consecutive cohort of 113 AIS patients with progressive main thoracic deformity. Demographic data, the Adams test and eight radiographic torsion-related coronal and sagittal deformity parameters [apical vertebral rotation (AVR)-Stokes method, Mehta angle (RVAD), main thoracic Cobb side-bending, T5-T12 kyphosis, T5-T8 kyphosis, T9-T12 kyphosis, kyphotic change and double rib contour sign (rib index)] were correlated between each other and with the main thoracic Cobb angle (MTCobb). Univariate linear regression and multiple linear stepwise regression analyses were performed as well.

RESULTS

The radiographically measurable deformity parameters that best correlated with the MTCobb angle in idiopathic curves were: side-bending, RVAD, AVR and the Adams test. Sagittal variables were correlated the least with MTCobb. Coronal parameters as AVR, RVAD, side-bending and Adam test are highly intercorrelated. Sagittal variables are related between each other but are not directly related to coronal parameters.

CONCLUSIONS

There is a strong relationship between the Cobb angle, curve bending, the Mehta angle and the apical vertebral rotation. Together with the clinical Adams test, these are the most important radiographic torsion-related parameters to measure when assessing scoliosis in 2D.

LEVEL OF EVIDENCE

3.

Accurate prediction of height loss in adolescent idiopathic scoliosis: Cobb angle alone is insufficient

PURPOSE

Spinal height loss due to scoliosis was mostly calculated by equations with Cobb angle as the unique independent variable in adolescent idiopathic scoliosis (AIS), with their accuracy being seriously doubted. The purpose of this study was to compare and correlate the measured loss in spinal height (ΔSHm) with the calculated loss in spinal height (ΔSHc), and to identify the key factors associated with height loss in AIS.

METHODS

This retrospective study included two stages. In stage I, 277 surgically treated AIS patients were reviewed, and divided into single curve and double curve groups. The accuracy and limitation of each correction equation was testified by comparing the data sets of ΔSHc with the ΔSHm, as well as comparing the pre- and post-op spinal length for each correction equation. In stage II, 235 curves within 100 AIS patients were selected to explore the relationship between loss in vertical curve height (△CH) and Cobb angle, curve length (CL), number of vertebrae within the curve (NVC), tilt angle of each curve (α) through partial correlation analysis.

RESULTS

In stage I, the △SHm averaged 3.5 cm in single curve group and 4.8 cm in double curve group. The ΔSHc was only comparable with ΔSHm using the Bjure's equation. Pre- and post-op spinal length was only comparable in Bjure's corrected group with Cobb angle <60° (p > 0.05). In stage II, the partial correlation coefficients of △CH with Cobb angle, CL, α, and NVC were 0.889, 0.493, -0.723 and -0.175 (p < 0.01), respectively. The △CH could be calculated by the following formula: △CH (mm) = 29.305 + 0.506Cobb + 0.083CL - 0.592α - 0.796NVC.

CONCLUSIONS

Previous height correction equations employing Cobb angle as the unique independent variable are inaccurate. Cobb angle, curve length, curve inclination, and number of vertebrae within the curve are all strong determinants responsible for the height loss in AIS.

Assessment of Lowest Instrumented Vertebra Tilt on Radiographic Measurements in Lenke "C" Modifier Curves Undergoing Selective Thoracic Fusion in Adolescent Idiopathic Scoliosis

STUDY DESIGN

Multicenter, retrospective cohort study.

OBJECTIVES

The purpose of this study is to determine how the amount of residual lowest instrumented vertebra (LIV) tilt correlates with radiographic measurements. When performing a selective thoracic posterior spinal fusion for adolescent idiopathic scoliosis (AIS), the LIV may be tilted into the lumbar curve or made horizontal.

METHODS

This is a multicenter retrospective study of 33 consecutive patients with AIS, Lenke types 1 to 4, lumbar modifier C, and a minimum follow-up of 2 years, who underwent selective thoracic posterior spinal fusions. Measurements obtained from pre- and postoperative radiographs were correlated with postoperative LIV tilt.

RESULTS

At final follow-up, less postoperative LIV tilt significantly correlated with less thoracic apical translation (p =.023) when controlling for the position of the LIV relative to the stable vertebra and preoperative thoracic and lumbar curve flexibility. LIV tilt was not significantly associated with thoracic Cobb angle, lumbar Cobb angle, lumbar apical translation, coronal balance, sagittal balance, or the amount of correction obtained compared to their preoperative measurements (p >.05).

CONCLUSION

Decreased LIV tilt was significantly associated with decreased thoracic apical translation. LIV tilt did not significantly correlate with coronal balance or any other radiographic measurement. We caution that these findings may only be applicable in C modifier curves and when the correct LIV is chosen.

LEVEL OF EVIDENCE

Level III, Therapeutic study.

Rod rotation and differential rod contouring followed by direct vertebral rotation for treatment of adolescent idiopathic scoliosis: effect on thoracic and thoracolumbar or lumbar curves assessed with intraoperative computed tomography

BACKGROUND CONTEXT

Although direct vertebral rotation (DVR) is now used worldwide for the surgical treatment of adolescent idiopathic scoliosis (AIS), the benefit of DVR in reducing vertebral body rotation in these patients has not been determined.

PURPOSE

We investigated a possible additive effect of DVR on further reduction of vertebral body rotation in the axial plane following intraoperative rod rotation or differential rod contouring in patients undergoing surgical treatment for AIS.

STUDY DESIGN/SETTING

The study was a prospective computed tomography (CT) image analysis.

PATIENT SAMPLE

We analyzed the results of the two intraoperative procedures in 30 consecutive patients undergoing surgery for AIS (Lenke type I or II: 15; Lenke type V: 15).

OUTCOME MEASURES

The angle of reduction of vertebral body rotation taken by intraoperative CT scan was measured and analyzed. Pre- and postoperative responses to the Scoliosis Research Society 22 Questionnaire (SRS-22) were also analyzed.

METHODS

To analyze the reduction of vertebral body rotation with rod rotation or DVR, intraoperative cone-beam CT scans of the three apical vertebrae of the major curve of the scoliosis (90 vertebrae) were taken pre-rod rotation (baseline), post-rod rotation with differential rod contouring, and post-DVR in all patients. The angle of vertebral body rotation in these apical vertebrae was measured and analyzed for statistical significance. Additionally, differences between thoracic curve scoliosis (Lenke type I or II; 45 vertebrae) and thoracolumbar or lumbar curve scoliosis (Lenke type V; 45 vertebrae) were analyzed. Pre- and postoperative SRS-22 scores were evaluated in all patients.

RESULTS

The mean (90 vertebrae) vertebral body rotation angles at baseline, post-rod rotation or differential rod contouring, and post-rod rotation or differential rod contouring or post-DVR were 17.3°, 11.1°, and 6.9°, respectively. The mean reduction in vertebral body rotation with the rod rotation technique was 6.8° for thoracic curves and 5.7° for thoracolumbar or lumbar curves (p<.00005). The mean additional reduction in rotation with the DVR technique was 3.4° for thoracic curves and 4.9° for thoracolumbar or lumbar curves (p<.00005). Direct vertebral rotation displayed a slightly but significantly greater additive effect in reducing rotation following initial reduction with rod rotation or differential rod contouring in thoracolumbar or lumbar than in thoracic curves. In the SRS-22 results, postoperative self-image was significantly better than preoperative image in both groups.

CONCLUSIONS

Direct vertebral rotation contributed an additional reduction in vertebral body rotation in thoracic and thoracolumbar or lumbar curves. The DVR technique is likely to be more useful in thoracolumbar or lumbar curve scoliosis than in thoracic curve scoliosis.

Selection of the upper vertebra to be instrumented in the treatment of thoracolumbar and lumbar adolescent idiopathic scoliosis by anterior correction and fusion surgery using dual-rod instrumentation: a minimum 12-year follow-up study

BACKGROUND CONTEXT

Consensus regarding the optimal upper vertebra to be instrumented during surgical treatment of Lenke 5C thoracolumbar and lumbar adolescent idiopathic scoliosis (AIS) remains limited.

PURPOSE

This study aimed to assess whether a short fusion strategy is appropriate for correction of a Lenke 5C AIS curve by anterior correction and fusion surgery using dual-rod instrumentation.

STUDY DESIGN

This study design used retrospective comparative analysis of a prospectively collected, consecutive, non-randomized series of patients at a single institution.

PATIENT SAMPLE

Thirty consecutive patients with Lenke 5C AIS treated with anterior correction and fusion surgery using dual-rod instrumentation were included.

OUTCOME MEASURES

Patient demographics, radiographic measurements, and Scoliosis Research Society-22 questionnaire (SRS-22) scores were the outcome measures for this study.

METHODS

Thirty patients were treated surgically for AIS with a Lenke 5C curve (mean age, 14.4 years [11-19 years)]) and followed up for a mean period of 17.2 years (12-23 years). Radiographical parameters and clinical outcomes were compared between patients treatment with the end vertebra (EV) instrumented (n=14) and those treated by short fusion (S group) with instrumentation starting at the vertebra one level caudal to the EV (n=16 patients). There were no study-specific biases related to conflicts of interest.

RESULTS

In the EV group, a mean preoperative Cobb angle of 56° was corrected to 5° after surgery and to 8° at the final follow-up. In the S group, a mean preoperative Cobb angle of 55° was corrected to 10° after surgery and 14° at the final follow-up. The mean correction rate at the final follow-up was significantly lower in the S group (74%) than in the EV group (86%; p=.020). The coronal and sagittal balance, thoracic kyphosis, lumbar lordosis, and clinical outcomes evaluated using SRS-22 did not differ between the two groups.

CONCLUSIONS

The short fusion strategy, which involves instrumentation of the vertebra one level caudal to the upper EV, can be considered as an alternative to the conventional strategy, which includes instrumentation of the upper EV, for treating Lenke 5C curves via anterior spinal fusion.

Bracing and exercise-based treatment for idiopathic scoliosis

BACKGROUND

Various conservative therapies are available for treating adolescent idiopathic scoliosis (AIS), however, the disparities between them and the evidence of their efficacy and effectiveness is still unclear.

OBJECTIVES

To evaluate the effectiveness of different conservative treatments on AIS.

METHODS

A literature-based narrative review of the English language medical literature.

RESULTS AND CONCLUSIONS

The most appropriate treatment for each patient should be chosen individually and based on various parameters. Bracing has been found to be a most effective conservative treatment for AIS. There is limited evidence that specific physical exercises also an effective intervention for AIS. Exercise-based physical therapy, if correctly administered, can prevent a worsening of the curve and may decrease need for bracing. In addition, physical exercises were found to be the only treatment improving respiratory function. Combining bracing with exercise increases treatment efficacy compared with a single treatment. Additional, well-designed and good quality studies are required to assess the effectiveness of different conservative methods in treating AIS.

Three-dimensional morphology study of surgical adolescent idiopathic scoliosis patient from encoded geometric models

PURPOSE

The classification of three-dimensional (3D) spinal deformities remains an open question in adolescent idiopathic scoliosis. Recent studies have investigated pattern classification based on explicit clinical parameters. An emerging trend however seeks to simplify complex spine geometries and capture the predominant modes of variability of the deformation. The objective of this study is to perform a 3D characterization and morphology analysis of the thoracic and thoraco/lumbar scoliotic spines (cross-sectional study). The presence of subgroups within all Lenke types will be investigated by analyzing a simplified representation of the geometric 3D reconstruction of a patient's spine, and to establish the basis for a new classification approach based on a machine learning algorithm.

METHODS

Three-dimensional reconstructions of coronal and sagittal standing radiographs of 663 patients, for a total of 915 visits, covering all types of deformities in adolescent idiopathic scoliosis (single, double and triple curves) and reviewed by the 3D Classification Committee of the Scoliosis Research Society, were analyzed using a machine learning algorithm based on stacked auto-encoders. The codes produced for each 3D reconstruction would be then grouped together using an unsupervised clustering method. For each identified cluster, Cobb angle and orientation of the plane of maximum curvature in the thoracic and lumbar curves, axial rotation of the apical vertebrae, kyphosis (T4-T12), lordosis (L1-S1) and pelvic incidence were obtained. No assumptions were made regarding grouping tendencies in the data nor were the number of clusters predefined.

RESULTS

Eleven groups were revealed from the 915 visits, wherein the location of the main curve, kyphosis and lordosis were the three major discriminating factors with slight overlap between groups. Two main groups emerge among the eleven different clusters of patients: a first with small thoracic deformities and large lumbar deformities, while the other with large thoracic deformities and small lumbar curvature. The main factor that allowed identifying eleven distinct subgroups within the surgical patients (major curves) from Lenke type-1 to type-6 curves, was the location of the apical vertebra as identified by the planes of maximum curvature obtained in both thoracic and thoraco/lumbar segments. Both hypokyphotic and hyperkypothic clusters were primarily composed of Lenke 1-4 curve type patients, while a hyperlordotic cluster was composed of Lenke 5 and 6 curve type patients.

CONCLUSION

The stacked auto-encoder analysis technique helped to simplify the complex nature of 3D spine models, while preserving the intrinsic properties that are typically measured with explicit parameters derived from the 3D reconstruction.

Understanding how axial loads on the spine influence segmental biomechanics for idiopathic scoliosis patients: A magnetic resonance imaging study

BACKGROUND

Segmental biomechanics of the scoliotic spine are important since the overall spinal deformity is comprised of the cumulative coronal and axial rotations of individual joints. This study investigates the coronal plane segmental biomechanics for adolescent idiopathic scoliosis patients in response to physiologically relevant axial compression.

METHODS

Individual spinal joint compliance in the coronal plane was measured for a series of 15 idiopathic scoliosis patients using axially loaded magnetic resonance imaging. Each patient was first imaged in the supine position with no axial load, and then again following application of an axial compressive load. Coronal plane disc wedge angles in the unloaded and loaded configurations were measured. Joint moments exerted by the axial compressive load were used to derive estimates of individual joint compliance.

FINDINGS

The mean standing major Cobb angle for this patient series was 46°. Mean intra-observer measurement error for endplate inclination was 1.6°. Following loading, initially highly wedged discs demonstrated a smaller change in wedge angle, than less wedged discs for certain spinal levels (+2,+1,-2 relative to the apex, (p<0.05)). Highly wedged discs were observed near the apex of the curve, which corresponded to lower joint compliance in the apical region.

INTERPRETATION

While individual patients exhibit substantial variability in disc wedge angles and joint compliance, overall there is a pattern of increased disc wedging near the curve apex, and reduced joint compliance in this region. Approaches such as this can provide valuable biomechanical data on in vivo spinal biomechanics of the scoliotic spine, for analysis of deformity progression and surgical planning.

Usefulness of Simple Rod Rotation to Correct Curve of Adolescent Idiopathic Scoliosis

Objective

To correct apical vertebral rotation for adolescent idiopathic scoliosis (AIS), direct vertebral derotation (DVD) or simple rod rotation (SRR) might be considered. The aim of the present study is to introduce the surgical experiences of AIS by a Korean neurosurgeon and to evaluate the effectiveness of SRR for apical vertebral rotation.

Methods

A total of 9 patients (1 male and 8 females) underwent scoliosis surgery by a neurosurgeon of our hospital. The Lenke classifications of the patients were 1 of 1B, 2 of 1C, 1 of 2A, 1 of 2C, 3 of 5C and 1 of 6C. Surgery was done by manner of simple rod rotation on the concave side and in situ coronal bending. Coronal Cobb's angles, vertebral rotation angles and SRS-22 were measured on a plain standing X-ray and CT before and after surgery.

Results

The mean follow up period was 25.7 months (range : 5–52). The mean number of screw positioning level was nine (6–12). The mean age was 16.4 years (range : 13–25) at surgery. The mean Risser grade was 3.7±0.9. The apical vertebral rotation measured from the CT scans was 25.8±8.5° vs. 9.3±6.7° (p<0.001) and the Coronal Cobb's angle was 53.7±10.4° vs. 15.4±6.5° (p<0.001) preoperatively and postoperative, respectively. The SRS-22 improved from 71.9 preoperatively to 90.3 postoperatively. There were no complications related with the operations.

Conclusion

SRR with pedicle screw instrumentation could be corrected successfully by axial rotation without complications. SRR might serve as a good option to correct AIS deformed curves of AIS.

Thoracic sagittal plane variations between patients with thoracic adolescent idiopathic scoliosis and healthy adolescents

PURPOSE

To analyze the sagittal thoracic parameters of different types of progressive thoracic adolescent idiopathic scoliosis (AIS) patients and compare them with healthy adolescents.

METHODS

115 AIS patients with main thoracic curves (Cobb: 59.4 ± 12.7) were prospectively compared with 116 healthy adolescents. The AIS and control (C) groups were homogeneous in terms of age and gender. Standing sagittal radiographs were analyzed for differences in T5-T12 kyphosis, T5-T8 and T9-T12 segmental kyphosis, the change between these two angles, and the double rib contour sign. Statistical analyses were performed using the χ ², one-way ANOVA, Mann-Whitney U and Student's t tests.

RESULTS

The sagittal parameters of Lenke 1 curves did not differ from healthy adolescents (T5-T8: 17.1 ± 10 vs C: 16 ± 7; T9-T12: 6.3 ± 7 vs C: 7.9 ± 5; T5-T12: 23.9 ± 14 vs C: 23.9 ± 8). Compared with the controls, Lenke type 3 curves were globally more hypokyphotic (T5-T12: 18.9 ± 12 vs C: 23.9 ± 8, P = 0.027) due to a "lordosis" of the lower thoracic segment (T9-T12: 0.9 ± 10 vs C: 7.9 ± 5, P = 0.001). Type 2 curves tended to exhibit more pronounced upper thoracic kyphosis (T5-T8: 20.7 ± 12 vs C: 16 ± 7). Both types 2 and 3 require a marked TK changes in the transition between the upper and lower thoracic segments to compensate for global (T5-T12) kyphosis.

CONCLUSIONS

In this 2D analysis of moderate AIS, Lenke 1 curves exhibited normal thoracic sagittal parameters, which brings into question the effect of lordosis on the development of single thoracic curves. Lenke 3 curves exhibited lower thoracic segmental hypokyphosis, and the type 2 showed upper segmental hyperkyphosis. These results should be considered when planning a surgical strategy.

Does an Internal Thoracoplasty Correct and Prevent a Reassertion of the Rib Cage Deformity After Spine Surgery for an Adolescent Idiopathic Thoracic Scoliosis Greater Than 70 Degrees

STUDY DESIGN

Prospective observational study.

OBJECTIVE

To evaluate the effect of internal thoracoplasty and anterior spine release combined with posterior spinal instrumentation in correcting and preventing a reoccurrence of the rib cage deformity in adolescent idiopathic thoracic scoliosis >70 degrees.

SUMMARY OF BACKGROUND DATA

The rib cage deformity rather than the lateral curvature of the spine is usually the major cosmetic deformity in severe adolescent idiopathic thoracic scoliosis. This can be difficult to treat and assess the effect of surgery.

METHODS

The Integrated Shape Imaging System was used to assess rib cage deformity before surgery and during follow-up for more than 2 years in 37 patients with an adolescent idiopathic thoracic scoliosis (Lenke 1) >70° (mean 81°) treated by internal thoracoplasty and anterior spine release combined with posterior spinal instrumentation using a hybrid construct.

RESULTS

The mean Cobb angle was reduced from 81° to 30° (63% correction). The rib cage deformity was improved in 30 patients (81%) because of a combination of both a reduction of the convex rib hump and an elevation of the concave rib depression. However, the effect on patients with an angle of thoracic inclination <16° was not as reliable. One year after surgery, additional improvement of the chest deformity had occurred in 9 patients. In none of the 37 patients was there any further progression of the rib cage deformity.

CONCLUSION

An internal thoracoplasty was effective in improving and/or stabilizing the rib cage deformity as well as achieving good correction of the scoliosis in patients with adolescent idiopathic thoracic scoliosis and severe deformity.

Reliability and Validity Testing of a Danish Translated Version of the Scoliosis Research Society Instrument-22 Revised (SRS-22R)

STUDY DESIGN

Cross-sectional Objectives: To present a reliable and valid Danish translation of the Scoliosis Research Society-22R (SRS-22R).

SUMMARY OF BACKGROUND DATA

The SRS22R was designed as a disease-specific measure of quality of life in surgically treated adolescent idiopathic scoliosis (AIS) patients. It has been translated and adapted into several languages. A reliable and valid Danish version is not available.

METHODS

A Danish version of the SRS-22R was developed using previously published and widely accepted guidelines. The final Danish SRS-22R and the Danish Short Form-36 were administered to 169 AIS patients and 45 healthy controls. Cronbach's α was computed as a measure of internal consistency. Concordant validity was determined by computing correlations of the SRS-22R Domains with the corresponding SF-36 domains and factor analysis. Discriminant validity was determined by comparing Domain scores between AIS patients treated surgically, AIS patients treated with a brace, and the healthy controls.

RESULTS

One hundred sixty-five (97.6%) AIS patients and 42 (93.3%) healthy controls returned their questionnaires. Moderate ceiling effects were observed in the AIS cohort for the Function and Satisfaction Domains. Cronbach's α for each Domain and the Total score were good to excellent. Pearson correlation coefficients were found to be high for the SRS-22R Domains that had similar latent variables as the SF-36 Domains. Factor analysis revealed an underlying factorial structure of the questionnaire accounting for 60% of the explained variance. The SRS-22R Domain scores were statistically significantly different between the AIS cohort that had surgery, the AIS cohort that was treated with a brace, and the healthy controls.

CONCLUSIONS

The Danish version of the SRS-22R is reliable, with content, concordant, and discriminant validity. The scores, the score distribution, and the ceiling and floor effects were similar to those of the original SRS-22R in English as well as other previous translations.

The effect of metal density in thoracic adolescent idiopathic scoliosis

PURPOSE

Determine impact of metal density on curve correction and costs in thoracic adolescent idiopathic scoliosis (AIS). Ascertain if increased metal density is required for larger or stiffer curves.

METHODS

Multicentre retrospective case series of patients with Lenke 1-2 AIS treated with single-stage posterior only surgery using a standardized surgical technique; constructs using >80 % screws with variable metal density. All cases had >2-year follow up. Outcomes measures included coronal and sagittal radiographic outcomes, metal density (number of instrumented pedicles vs total available), fusion length and cost.

RESULTS

106 cases included 94 female. 78 Lenke 1. Mean age 14 years (9-26). Mean main thoracic (MT) Cobb angle 63° corrected to 22° (66 %). No significant correlations were present between metal density and: (a) coronal curve correction rates of the MT (r = 0.13, p = 0.19); (b) lumbar curve frontal correction (r = -0.15, p = 0.12); (c) correction index in MT curve (r = -0.10, p = 0.32); and (d) correction index in lumbar curve (r = 0.11, p = 0.28). Metal density was not correlated with change in thoracic kyphosis (r = 0.22, p = 0.04) or lumbosacral lordosis (r = 0.27, p = 0.01). Longer fusions were associated with greater loss of thoracic kyphosis (r = -0.31, p = 0.003). Groups differing by preoperative curve size and stiffness had comparable corrections with similar metal density. The pedicle screw cost represented 21-29 % of overall cost of inpatient treatment depending on metal density.

CONCLUSIONS

Metal density affects cost but not the coronal and sagittal correction of thoracic AIS. Neither larger nor stiffer curves necessitate high metal density.

The change on vertebral axial rotation after posterior instrumentation of idiopathic scoliosis

PURPOSE

Agreement between the correction objectives and the instrumentation strategies remains controversial in idiopathic scoliosis. Most studies have focus on the frontal and sagittal plane. The goal of this study was to evaluate the change on vertebral axial rotation after posterior instrumentation in fused and unfused segments.

METHODS

Fourteen patients operated on for idiopathic scoliosis were prospectively included. Fusion and instrumentation were done by posterior approach. All patients had a pre-operative and a 10-day post-operative radiological evaluation with the EOS system. Axial orientation of the vertebrae with special interest to the apical, junctional, and unfused areas was obtained thanks to the reconstruction software.

RESULTS

Mean apical vertebra axial rotation statistically decreased from 21° pre-operatively to 13° post-operatively. But, there were no statistically significant differences between pre-operative and post-operative mean axial intervertebral rotations in the main curve and axial rotation of the non-instrumented lower counter curve.

CONCLUSIONS

3D analysis of the spine in standing position is a great advancement for post-operative analysis of adolescent idiopathic scoliosis (AIS) corrections. This study confirmed that actual instrumentations are able to achieve "en bloc" 3D correction of the spine but not intervertebral axial rotation correction.

Sagittal Alignment Two Years After Selective and Nonselective Thoracic Fusion for Lenke 1C Adolescent Idiopathic Scoliosis

STUDY DESIGN/SETTING

Matched cohort.

OBJECTIVE

To evaluate thoracic and thoracolumbar sagittal Cobb angles in patients undergoing either selective thoracic fusion (STF) or nonselective thoracic fusion (NSTF) for Lenke 1C adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

The Lenke classification is used to guide fusion levels in AIS. For some curve types, including 1C, there is a disparity in practice regarding whether the thoracolumbar/lumbar curve should be included in the arthrodesis. The impact of performing an NSTF on sagittal parameters has not been adequately evaluated.

METHODS

A multicenter database of AIS was queried for patients with right-sided 1C curves treated with posterior correction and fusion. A matched cohort for each group was created based on age, gender, preoperative Cobb angles, and Scoliosis Research Society-22R domain scores. Independent t tests for continuous variables and Fisher exact test for categorical variables were used to compare the STF and NSTF groups.

RESULTS

Thirty-eight patients who underwent NSTF were matched to 38 patients in the STF. An average of 8.0 levels were fused in the STF group and 11.6 in the NSTF group (p < .001). Preoperative and radiographic variables were similar between the two groups. Postoperatively, there was a statistically significant difference between the STF and NSTF sagittal Cobb in the thoracic spine, 26.9° and 21.7° (p = .013). The greatest difference was in the thoracolumbar sagittal Cobb, which increased to 4.3° kyphosis in the STF group and decreased to 9° of lordosis in the NSTF group (p < .001). Residual thoracolumbar/lumbar scoliosis was 25.5° in the STF group and 14.5° in the NSTF group (p < .001).

CONCLUSIONS

STF in 1C curves preserves lumbar motion segments but may be associated with an increase in thoracic and thoracolumbar kyphosis compared to NSTF. As expected, residual thoracolumbar/lumbar scoliosis was less in the NSTF group compared to the STF group. Although the long-term implications of these changes are unknown, consideration of sagittal balance is critical. Following these patients in the medium and long term will provide important information to guide fusion levels.

LEVEL OF EVIDENCE

II.

Partial Intervertebral Fusion Secures Successful Outcomes After Thoracoscopic Anterior Scoliosis Correction: A Low-Dose Computed Tomography Study

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVES

To analyze intervertebral (IV) fusion after thoracoscopic anterior spinal fusion (TASF) and explore the relationship between fusion scores and key clinical variables.

SUMMARY OF BACKGROUND INFORMATION

TASF provides comparable correction with some advantages over posterior approaches but reported mechanical complications, and their relationship to non-union and graft material is unclear. Similarly, the optimal combination of graft type and implant stiffness for effecting successful radiologic union remains undetermined.

METHODS

A subset of patients from a large single-center series who had TASF for progressive scoliosis underwent low-dose computed tomographic scans 2 years after surgery. The IV fusion mass in the disc space was assessed using the 4-point Sucato scale, where 1 indicates <50% and 4 indicates 100% bony fusion of the disc space. The effects of rod diameter, rod material, graft type, fusion level, and mechanical complications on fusion scores were assessed.

RESULTS

Forty-three patients with right thoracic major curves (mean age 14.9 years) participated in the study. Mean fusion scores for patient subgroups ranged from 1.0 (IV levels with rod fractures) to 2.2 (4.5-mm rod with allograft), with scores tending to decrease with increasing rod size and stiffness. Graft type (autograft vs. allograft) did not affect fusion scores. Fusion scores were highest in the middle levels of the rod construct (mean 2.52), dropping off by 20% to 30% toward the upper and lower extremities of the rod. IV levels where a rod fractured had lower overall mean fusion scores compared to levels without a fracture. Mean total Scoliosis Research Society (SRS) questionnaire scores were 98.9 from a possible total of 120, indicating a good level of patient satisfaction.

CONCLUSIONS

Results suggest that 100% radiologic fusion of the entire disc space is not necessary for successful clinical outcomes following thoracoscopic anterior selective thoracic fusion.

Motor and somatosensory abnormalities are significant etiological factors for adolescent idiopathic scoliosis

OBJECTIVE

In adolescent idiopathic scoliosis (AIS), we explore the role of lateralized motor and somatosensory abnormalities as a possible etiological factor.

METHODS

Intraoperative transcranial electrical stimulation was performed in 15 AIS and 14 adult degenerative scoliosis (ADS) patients. Inter-side motor output balance (MOB) by comparing the ratios of right to left motor evoked potentials (MEP) amplitudes, and inter-side motor output excitability (MOE) computed with MEP amplitude, was determined separately for both patients groups. For somatosensory evoked potentials (SSEP), peak to peak P37 amplitudes from right and left lower limb SSEP and inter-side P37 amplitude ratios were obtained.

RESULTS

Inter-side MOB was significantly asymmetric in AIS patients, contributed mainly by inter-side MOB changes in the upper than the lower limbs. Inter-side MOE comparisons of ipsilateral and contralateral MEP amplitudes were significantly different between AIS and ADS patients. Mean upper limb MEP amplitudes were significantly reduced in AIS patients. Amplitude of the right upper limb MEPs were positively correlated with inter-side MEP ratio. AIS patients show larger mean MEP amplitudes on the same side as the scoliotic curve. Overall, no correlation of Cobb's angle or total levels of scoliosis involvement with inter-side MOB and MOE parameters was found. Inter-side SSEP ratios were significantly higher in AIS patients.

CONCLUSIONS

Primary dysfunctional and distributed motor output contributing to abnormalities of inter-side MOB and MOE changes involving the upper limbs is evident in AIS. Simultaneous but independent somatosensory and motor observations seen these patients suggest a central mechanism as an etiological factor.

Abnormal Bone Mechanical and Structural Properties in Adolescent Idiopathic Scoliosis: A Study with Finite Element Analysis and Structural Model Index

Previous studies found adolescent idiopathic scoliosis (AIS) is associated with low bone mineral density (BMD) and abnormal bone quality, whilst the association between AIS and their bone strength is unknown. From high-resolution peripheral quantitative computed tomography-generated images, bone mechanical properties can be evaluated with finite element analysis (FEA), and trabecular rod-plate configuration related to trabecular bone strength can be quantified by structure model index (SMI). This study aimed to compare trabecular configuration and bone mechanical properties between AIS and the controls. 95 AIS girls aged 12-14 years and 97 age- and gender-matched normal controls were recruited. Bilateral femoral necks and non-dominant distal radius were scanned by dual-energy X-ray absorptiometry for areal BMD and HR-pQCT for SMI and FEA, respectively. Subjects were further classified into osteopenic and non-osteopenic group based on their areal BMD. Bone mechanical properties (stiffness, failure load and apparent modulus) were calculated using FEA. Linear regression model was used for controlling age, physical activity and calcium intake. AIS was associated with lower failure load and apparent modulus after adjusting for age, whereas AIS was associated with lower apparent modulus after adjusting for all confounders. Osteopenic AIS was associated with more rod-like trabeculae when compared with non-osteopenic AIS, whereas no difference was detected between osteopenic and non-osteopenic controls. This might be the result of abnormal regulation and modulation of bone metabolism and bone modelling and remodelling in AIS which will warrant future studies with a longitudinal design to determine the significance of micro-architectural abnormalities in AIS.

Sensory reweighting is altered in adolescent patients with scoliosis: Evidence from a neuromechanical model

Idiopathic scoliosis is the most frequent spinal deformity in adolescence. While its aetiology remains unclear, impairments in balance control suggest a dysfunction of the sensorimotor control mechanisms. The objective of this paper is to evaluate the ability of patients with idiopathic scoliosis to reweigh sensory information. Using a neuromechanical model, the relative sensory weighting of vestibular and proprioceptive information was assessed. Sixteen healthy adolescents and respectively 20 and 16 adolescents with mild or severe scoliosis were recruited. Binaural bipolar galvanic vestibular stimulation was delivered to elicit postural movement along the coronal plane. The kinematics of the upper body, using normalized horizontal displacement of the 7th cervical vertebra, was recorded 1s before, 2s during, and 1s following vestibular stimulation. The neuromechanical model included active feedback mechanisms that generated corrective torque from the vestibular and proprioceptive error signals. The model successfully predicted the normalized horizontal displacement of the 7th cervical vertebra. All groups showed similar balance control before vestibular stimulation; however, the amplitude (i.e., peak horizontal displacement) of the body sway during and immediately following vestibular stimulation was approximately 3 times larger in patients compared to control adolescents. The outcome of the model revealed that patients assigned a larger weight to vestibular information compared to controls; vestibular weight was 6.03% for controls, whereas it was 13.09% and 13.26% for the mild and severe scoliosis groups, respectively. These results suggest that despite the amplitude of spine deformation, the sensory reweighting mechanism is altered similarly in adolescent patients with scoliosis.

How quantity and quality of brace wear affect the brace treatment outcomes for AIS

PURPOSE

To determine the reliability of a prognostic curve progression model and the role of the quantity and quality of brace wear for adolescent idiopathic scoliosis (AIS) brace treatment.

METHODS

To develop a curve progression model for full-time AIS brace treatment, 20 AIS subjects (Group 1) prescribed full-time thoracolumbar sacral orthosis (TLSO) were monitored and followed for 2 years beyond maturity. The developed curve progression model was: curve progression (in degrees) = 33 + 0.11 × Peterson risk (%) - 0.07 in-brace correction (%) - 0.45 × quality (%) - 0.48 × quantity (%) + 0.0062 × quantity × quality. To validate the model, 40 new (test) subjects (Group 2) who met the same inclusion criteria and used the same type of monitors, were monitored and followed for 2 years after bracing.

RESULTS

For the 40 test subjects (Group 2), the average in-brace correction was 40 ± 22 %. The average quantity and quality of the brace wear were 56 ± 19 and 55 ± 17 %, respectively. Twelve subjects (30 %) progressed of which 10 subjects (25 %) required surgery and 28 subjects (70 %) showed no progression. The accuracy of the model to determine which patients would progress was 88 % (35/40) which was better than the Peterson's risk model (68 %; 26/40) alone. Patients who had the combined quantity times the quality over a threshold 43 % had a success treatment rate of 95 %.

CONCLUSIONS

This study showed the prognostic model of brace treatment outcome on AIS patients treated with full-time TLSO was reliable. Both the quantity and quality of the brace wear were important factors in achieving successful brace treatment.

The effect of Schroth exercises added to the standard of care on the quality of life and muscle endurance in adolescents with idiopathic scoliosis-an assessor and statistician blinded randomized controlled trial: "SOSORT 2015 Award Winner"

Background

In North America, care recommendations for adolescents with small idiopathic scoliosis (AIS) curves include observation or bracing. Schroth scoliosis-specific exercises have demonstrated promising results on various outcomes in uncontrolled studies. This randomized controlled trial (RCT) aimed to determine the effect of Schroth exercises combined with the standard of care on quality-of-life (QOL) outcomes and back muscle endurance (BME) compared to standard of care alone in patients with AIS.

Material and Methods

Fifty patients with AIS, aged 10–18 years, with curves 10–45 °, recruited from a scoliosis clinic were randomized to receive standard of care or supervised Schroth exercises plus standard of care for 6 months. Schroth exercises were taught over five sessions in the first two weeks. A daily home program was adjusted during weekly supervised sessions. The assessor and the statistician were blinded. Outcomes included the Biering-Sorensen (BME) test, Scoliosis Research Society (SRS-22r) and Spinal Appearance Questionnaires (SAQ) scores. Intention-to-treat (ITT) and per protocol (PP) linear mixed effects models were analyzed. Because ITT and PP analyses produced similar results, only ITT is reported.

Results

After 3 months, BME in the Schroth group improved by 32.3 s, and in the control by 4.8 s. This 27.5 s difference in change between groups was statically significant (95 % CI 1.1 to 53.8 s, p = 0.04). From 3 to 6 months, the self-image improved in the Schroth group by 0.13 and deteriorated in the control by 0.17 (0.3, 95 % CI 0.01 to 0.59, p = 0.049). A difference between groups for the change in the SRS-22r pain score transformed to its power of four was observed from 3 to 6 months (85.3, 95 % CI 8.1 to 162.5, p = 0.03), where (SRS-22 pain score)⁴ increased by 65.3 in the Schroth and decreased by 20.0 in the control group. Covariates: age, self-efficacy, brace-wear, Schroth classification, and height had significant main effects on some outcomes. Baseline ceiling effects were high: SRS-22r (pain = 18.4 %, function = 28.6 %), and SAQ (prominence = 26.5 %, waist = 29.2 %, chest = 46.9 %, trunk shift = 12.2 % and shoulders = 18.4 %).

Conclusions

Supervised Schroth exercises provided added benefit to the standard of care by improving SRS-22r pain, self-image scores and BME. Given the high prevalence of ceiling effects on SRS-22r and SAQ questionnaires’ domains, we hypothesize that in the AIS population receiving conservative treatments, different QOL questionnaires with adequate responsiveness are needed.

Trial registration

Schroth Exercise Trial for Scoliosis NCT01610908.

Electronic supplementary material

The online version of this article (doi:10.1186/s13013-015-0048-5) contains supplementary material, which is available to authorized users.

An alternative to a randomised control design for assessing the efficacy and effectiveness of bracing in adolescent idiopathic scoliosis

Randomised controlled trials (RCTs) that assessed the efficacy of bracing for adolescent idiopathic scoliosis have suffered from small sample sizes, low compliance and lack of willingness to participate. The aim of this study was to assess the feasibility of a comprehensive cohort study for evaluating both the efficacy and the effectiveness of bracing in patients with adolescent idiopathic scoliosis. Patients with curves at greater risk of progression were invited to join a randomised controlled trial. Those who declined were given the option to remain in the study and to choose whether they wished to be braced or observed. Of 87 eligible patients (5 boys and 63 girls) identified over one year, 68 (78%) with mean age of 12.5 years (10 to 15) consented to participate, with a mean follow-up of 168 weeks (0 to 290). Of these, 19 (28%) accepted randomisation. Of those who declined randomisation, 18 (37%) chose a brace. Patients who were more satisfied with their image were more likely to choose bracing (Odds Ratio 4.1; 95% confidence interval 1.1 to 15.0; p = 0.035). This comprehensive cohort study design facilitates the assessment of both efficacy and effectiveness of bracing in patients with adolescent idiopathic scoliosis, which is not feasible in a conventional randomised controlled trial.

Selective Thoracic Fusion Provides Similar Health-Related Quality of Life but Can Cause More Lumbar Disc and Facet Joint Degeneration: A Comparison of Adolescent Idiopathic Scoliosis Patients With Normal Population 10 Years After Surgery

OBJECTIVES

To evaluate the long-term behavior of the lumbar curve in patients with adolescent idiopathic scoliosis treated with selective thoracic fusion and to assess the clinical and radiologic outcomes in this fusion group compared with an age- and gender-matched group.

SUMMARY OF BACKGROUND DATA

Selective thoracic fusion for the treatment of adolescent idiopathic scoliosis (AIS) preserves lumbar motion segments but leaves a residual deformity. By avoiding fusion of the lumbar spine, a greater mobility may be preserved, which may be an advantage in long-term follow-up in terms of degenerative changes in unfused segments.

METHODS

Group A included 25 AIS patients with mean a age of 23.8 years and a mean 11.4 years of follow-up. Group B included 30 age- and gender-matched subjects without any deformity. Preoperative, postoperative, and follow-up radiographs were reviewed. All patients had MRIs taken at the final follow-up in order to evaluate disc degeneration (DD) and facet joint degeneration (FJD) at the unfused lumbar spine. Clinical evaluation was done by using Scoliosis Research Society-22R, Oswestry Disability Index, and numerical rating scale.

RESULTS

Sagittal and coronal balance and lowest instrumented vertebra disc angulation were stable over time. Mean grading of lumbar DD was 2.16 (2-4) in Group A and 1.86 (1-3) in Group B. Lumbar FJDs were 2.05 (1-4) in Group A and 1.60 (1-3) in Group B. There was significant difference between the two groups for DD except for the L4-L5 level (p = .26). FJD was significantly higher in the L1-L2 and L2-L3 levels (L1-L2, p = .002, L2-L3, p = .002) but not for the other levels. Outcome scores were similar without significant differences between the two groups (p > .05).

CONCLUSION

Selective thoracic fusion provides satisfactory outcomes at more than 10 years of follow-up. Our study demonstrated a moderate increase in the rate of disc degeneration in the unfused segments. Facet joint degeneration was significant at the upper two levels adjacent to the lowest instrumented vertebra.

How Does Spinal Release and Ponte Osteotomy Improve Spinal Flexibility? The Law of Diminishing Returns

STUDY DESIGN

Experimental study.

OBJECTIVES

To evaluate the effect of stepwise resection of posterior spinal ligaments, facet joints, and ribs on thoracic spinal flexibility.

SUMMARY OF BACKGROUND DATA

Posterior spinal ligaments, facet joints and ribs are removed to increase spinal flexibility in corrective spinal surgery for deformities such as adolescent idiopathic scoliosis (AIS). Reported clinical results vary and biomechanical substantiation is lacking.

METHODS

Ten fresh-frozen human cadaveric thoracic spinal specimens (T6-T11) were studied. A spinal motion simulator applied a pure moment of ±2.5 Nm in flexion, extension, lateral bending (LB) and axial rotation (AR). Range of motion (ROM) was measured for the intact spine and measured again after stepwise resection of the supra/interspinous ligament (SIL), inferior facet, flaval ligament, superior facet, and rib heads.

RESULTS

SIL resection increased ROM in flexion (10.2%) and AR (3.1%). Successive inferior facetectomy increased ROM in flexion (4.1%), LB (3.8%) and AR (7.7%), and flavectomy in flexion (9.1%) and AR (2.5%). Sequential superior facetectomy only increased ROM in flexion (6.3%). Rib removal provided an additional increase in flexion (6.3%), LB (4.5%) and AR (13.0%). Extension ROM increased by 10.5% after the combined removal of the SIL, inferior facet and flaval ligament.

CONCLUSIONS

Posterior spinal releases in these non-scoliotic spines led to an incremental increase in spinal flexibility, but each sequential step had less effect. As compared to SIL resection with inferior facetectomy, additional superior facetectomy did not improve flexibility in AR and LB and only 6.3% in flexion. The data presented from this in vitro study should be interpreted with care, as no representative cadaveric spine model for AIS was available, However, the results presented here at least question the benefits of performing routine complete facetectomies (i.e. Ponte osteotomies) to increase spinal flexibility in scoliosis surgery.

Evolution of adolescent idiopathic scoliosis: results of a multicenter study at 20 years' follow-up

INTRODUCTION

To date there is no consensus on therapeutic indications in adolescent idiopathic scoliosis (AIS) with curvature between 30° and 60° at the end of growth.

OBJECTIVE

The objective of this study was to assess outcome in patients with moderate AIS.

MATERIAL AND METHODS

A multicenter retrospective study was conducted. Inclusion criteria were: Cobb angle, 30-60° at end of growth; and follow-up > 20 years. The data collected were angular values in adolescence and at last follow-up, and quality of life scores at follow-up.

RESULTS

A total of 258 patients were enrolled: 100 operated on in adolescence, 116 never operated on, and 42 operated on in adulthood. Mean follow-up was 27.8 years. Cobb angle progression significantly differed between the 3 groups: 3.2° versus 8.8° versus 23.6°, respectively; P < 0.001. In lumbar scoliosis, the risk of progression to ≥ 20° was significantly higher for initial Cobb angle > 35° (OR=4.278, P=0.002). There were no significant differences in quality of life scores.

DISCUSSION

Patients operated on in adolescence showed little radiological progression, demonstrating the efficacy of surgical treatment for curvature greater than 50°. Curvature greater than 40° was progressive and may require surgery in adulthood. Lumbar scoliosis showed greater potential progression than thoracic scoliosis in adulthood, requiring fusion as of 35° angulation.

LEVEL OF EVIDENCE

IV, retrospective study.

Radiological Outcomes in Adolescent Idiopathic Scoliosis Patients More Than 22 Years After Treatment

STUDY DESIGN

Longitudinal cohort.

OBJECTIVES

To evaluate the long-term radiologic outcomes in adolescent idiopathic scoliosis (AIS) patients more than 22 years after treatment.

SUMMARY OF BACKGROUND DATA

Although treatment for AIS is prophylactic and is aimed at preventing curve progression, very few studies report long-term outcomes of treatment.

METHODS

AIS patients treated with Boston brace or posterior spinal fusion (PSF) with Harrington-dorso-transverse traction (DTT) instrumentation from 1983 to 1990 were requested to return to clinic. Subsequently, 36-inch standing radiographs were obtained after patient consent. Cobb angles were compared with pretreatment and immediate posttreatment radiographs. Any evidence of adjacent-level disease or local kyphosis was also noted.

RESULTS

One hundred fifty-nine (78%) of 219 patients were available for follow-up, 66 braced and 93 surgical. There were 85 females with an average age at surgery of 14.3 years and an average age at follow-up of 37.6 years. The mean length of follow-up was 24.5 years (range, 22-30 years). There was a statistically significant curve progression of 2.9° in the PSF group. There was a greater degree of curve progression in the braced group (5.5°), but this was not statistically significant. Proximal segment degeneration was seen in 8 (5%), 2 in the brace cohort and 6 in the PSF cohort. Distal segment degeneration was seen in 26 (16%) patients, 4 treated with brace and 22 treated with PSF. No patient developed proximal junction kyphosis. Three patients in the PSF cohort required additional surgery for distal adding-on. Four patients had a noncontiguous L5-S1 fusion, three from the PSF cohort and one from the braced cohort.

CONCLUSION

In this cohort with an average follow-up of 24.5 years, with 78% available for follow-up, both the braced and surgically treated patients had a very small degree of curve progression, with a small incidence of distal segment degeneration and reoperation.

LEVEL OF EVIDENCE

III.

The Effects of Spinal Fusion on Lumbar Disc Degeneration in Patients with Adolescent Idiopathic Scoliosis: A Minimum 10-Year Follow-Up

STUDY DESIGN

Retrospective study.

OBJECTIVES

This study focused on patients with adolescent idiopathic scoliosis (AIS) who were followed up for more than 10 years, and assessed the influence of spinal balance on lumbar degenerative changes at distal unfused segments (DUS).

SUMMARY OF BACKGROUND DATA

Previous studies suggested that longer fusion segments may result in higher rates of occurrence of disc degeneration (DD) at unfused segments adjacent to the distal fused area. However, there are no existing studies that correlate the degree of DD to the location of lower instrumented vertebra (LIV) and the amount of the residual lumbar curve during the follow-up period.

METHODS

Radiologic measurements were recorded at the time of surgery, immediately after surgery, and 10 years after surgery. The Pfirrmann grading scale was used to rate the MR images of these patients. The presence of vertebral DD was also used to classify patients into DD+ and DD- groups.

RESULTS

93 patients with AIS participated in this study. The average age at the time of surgery was 15.2 years; the average follow-up time was 154 months. DD was found in 45 patients (48%) and L5/S1 was the most common (40%) location in those patients. The L1 group experienced DD at a frequency of 34%, whereas the frequency increased with lower LIV placement. There was a significant difference between DD+ and DD- in age at the time of operation, the L4 tilt (pre Op. and post. 10 years), and the number of mobile segments.

CONCLUSIONS

Disc degeneration occurred in 48% of the patients at the time of postop. 10 years. Disc degeneration had a tendency to occur in patients with greater preoperative and postoperative 10 years L4 tilt angle and fewer mobile segments in the lower lumbar spine.

LEVEL OF EVIDENCE

Level III.

A Preliminary Study of Estimation of Cobb's Angle From the Spinous Process Angle Using a Clinical Ultrasound Method

BACKGROUND

Over a lifetime of having radiographs, a patient with adolescent idiopathic scoliosis (AIS) can be cumulatively exposed to high doses of ionizing radiation. Therefore, radiation-free, effective, and low-cost methods to screen and diagnose scoliosis have been sought for years.

PURPOSE

This study aims to investigate the correlation between the Cobb's angle and the spinous process angle (SPA) and to study the feasibility of using clinical ultrasound images to estimate the Cobb's angle by measuring the SPA.

STUDY DESIGN

This manuscript includes a retrospective and a prospective study.

METHODS

In the retrospective study, radiographs from 43 subjects with AIS were used to investigate the correlation between the Cobb's angle and the SPA at the pre-brace and in-brace stages. Following this study, a prospective clinical ultrasound study was conducted on 33 subjects with AIS at the pre-brace stage to measure the SPA.

RESULTS

High intra-rater and inter-rater reliabilities of radiograph measurements were found (ICC[3,3] = 0.97, ICC[2,3] = 0.91, p < .05). The clinical ultrasound measurements were also found to be highly reliable (ICC[3,3] = 0.91, p < .05). There was a significant correlation (r = 0.80 at the pre-brace stage and r = 0.87 at the in-brace stage, p < .05) between the Cobb's angle and the SPA measured from the radiograph measurements, whereas the SPA measured from ultrasound images were found highly correlated with that measured from the radiographs at the pre-brace stage (r = 0.90, p < .01).

CONCLUSIONS

The findings of this study could support the new parameter (SPA) in the estimation of the Cobb's angle of a scoliotic curve in the coronal plane, and clinical ultrasound imaging could be developed and applied to assess scoliosis in a fast and noninvasive fashion.

LEVEL OF EVIDENCE

Level III.

Risks and outcomes of spinal deformity surgery in Chiari malformation, Type 1, with syringomyelia versus adolescent idiopathic scoliosis

BACKGROUND CONTEXT

Chiari malformation, Type 1, with syringomyelia (CIM+SM) is often associated with spinal deformity. The safety of scoliosis surgery this population is controversial and has never been directly compared with adolescent idiopathic scoliosis (AIS).

PURPOSE

The purpose of this study was to compare the safety and subjective outcomes of spinal deformity surgery between patients with Chiari malformation Type 1-associated scoliosis and a matched AIS cohort.

STUDY DESIGN

This study is based on a retrospective matched cohort analysis.

PATIENT SAMPLE

Patients with CIM+SM and treated with spinal fusion for spinal deformity were identified in the surgical records of a single institution and were matched, 1:1, with AIS patients undergoing spinal fusion at the same institution.

OUTCOME MEASURES

The outcome measures were neurological monitoring data quality and integrity, radiographic parameters, and Scoliosis Research Society Questionnaire-22 (SRS-22) scores.

METHODS

A clinical database was reviewed for patients undergoing spinal reconstruction for CIM+SM-associated spinal deformity at our institution from 2000 to 2012. Thirty-six CIM+SM patients were identified and matched to an AIS cohort (1:1) based on age, gender, major curve magnitude, fusion length, and revision status. Demographics, deformity morphology, surgical details, neuromonitoring data, and preoperative and postoperative SRS-22 scores were recorded at a minimum of 2-year follow-up. Changes in SRS-22 scores were compared within and between groups. Complications and neurological monitoring data issues were compared between groups.

RESULTS

Mean age was 14.5±5 years (CIM+SM: 14.6±5; AIS: 14.4±5), and 42% of patients were male. Preoperative mean major coronal Cobb measured 58°±25° versus 57°±17° (p=.84) with mean kyphosis 52°±17° versus 41°±20° (p=.018). An average of 10.4±2.6 vertebral levels were fused (10.4±2.8 vs. 10.4±2.3, p=.928). No differences existed in surgical approach (p=.336), estimated blood loss (680±720 vs. 660±310 mL, p=.845), or duration of surgery (6.0±2.2 vs. 5.6±2 hours, p=.434). Complication rate was comparable between the two groups (33% vs. 14%, p=.052). Chiari malformation, Type 1, with syringomyelia experienced more neurological complications (11% vs. 0%, p=.04) and neuromonitoring difficulties (28% vs. 3%, p=.007) than the AIS cohort. Mean curve correction was comparable at 2 years (58% CIM+SM vs. 64% AIS, p=.2). At follow-up, both CIM+SM and AIS groups demonstrated improved cumulative SRS-22 outcome subscores (CIM+SM: +0.4, p=.027; AIS: +0.3, p<.001). No difference in outcome subscores existed between CIM+SM and AIS groups.

CONCLUSIONS

Although CIM+SM patients undergoing spine reconstruction can expect similar deformity corrections and outcome scores to AIS patients, they also experience higher rates of neuromonitoring difficulties and neurological complications related to surgery. Surgeons should be prepared for these difficulties, particularly in children with larger syrinx size.

High-Volume Hospitals and Surgeons Experience Fewer Early Reoperation Events After Adolescent Idiopathic Scoliosis Surgery

STUDY DESIGN

Retrospective analysis of relevant in-hospital patient records from the New York State Inpatient Database.

OBJECTIVE

We aimed to assess reoperation risk in adolescent idiopathic scoliosis (AIS) by surgeon and hospital operative volume.

SUMMARY OF BACKGROUND DATA

The need for early reoperation can be devastating for patient and family, is a burden to the physician and adds significant cost. Previous studies have shown improved outcomes associated with higher volume surgeons and hospitals, but reoperation events have not yet been explored.

METHODS

The 2008-2011 New York State Inpatient Database was queried using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for adolescent idiopathic scoliosis patients aged 10-21 undergoing spine arthrodesis. Patient identifiers and revisit linkage variables were used to identify reoperation events. Annual surgeon and hospital volumes were stratified into tertiles (low, medium, high) via identifier codes. The relative risk of reoperation after spine arthrodesis was computed based on relevant patient inpatient stays.

RESULTS

Over 2008 to 2011, a total of 3,928 primary fusion operations for AIS were identified. The overall rate of reoperation after spine fusion for idiopathic scoliosis was 7.1%. Low volume surgeons performed less than 6 AIS fusions per year, medium volume surgeons performed less than 43, and high volume surgeons performed from 43 to 228. Reoperation after a primary fusion for adolescent idiopathic scoliosis showed reduced frequency among higher volume surgeons (14.1% for low vs. 5.1% for high, p<0.001, see Table for Hospitals).

CONCLUSIONS

Early reoperation after spine fusion for idiopathic scoliosis is seen more frequently in lower volume institutions and surgeons. Appreciating the resources and limitations at a clinician's institution is important to developing practices to prevent these devastating events. This work also has implications for strategies that aim to direct limited healthcare resources to centers with low complication rates.

Predictors of spine deformity progression in adolescent idiopathic scoliosis: A systematic review with meta-analysis

AIM: To evaluate published data on the predictors of progressive adolescent idiopathic scoliosis (AIS) in order to evaluate their efficacy and level of evidence.

METHODS: Selection criteria: (1) study design: randomized controlled clinical trials, prospective cohort studies and case series, retrospective comparative and none comparative studies; (2) participants: adolescents with AIS aged from 10 to 20 years; and (3) treatment: observation, bracing, and other. Search method: Ovid MEDLINE, Embase, the Cochrane Library, PubMed and patent data bases. All years through August 2014 were included. Data were collected that showed an association between the studied characteristics and the progression of AIS or the severity of the spine deformity. Odds ratio (OR), sensitivity, specificity, positive and negative predictive values were also collected. A meta-analysis was performed to evaluate the pooled OR and predictive values, if more than 1 study presented a result. The GRADE approach was applied to evaluate the level of evidence.

RESULTS: The review included 25 studies. All studies showed statistically significant or borderline association between severity or progression of AIS with the following characteristics: (1) An increase of the Cobb angle or axial rotation during brace treatment; (2) decrease of the rib-vertebral angle at the apical level of the convex side during brace treatment; (3) initial Cobb angle severity (> 25^o); (4) osteopenia; (5) patient age < 13 years at diagnosis; (6) premenarche status; (7) skeletal immaturity; (8) thoracic deformity; (9) brain stem vestibular dysfunction; and (10) multiple indices combining radiographic, demographic, and physiologic characteristics. Single nucleotide polymorphisms of the following genes: (1) calmodulin 1; (2) estrogen receptor 1; (3) tryptophan hydroxylase 1; (3) insulin-like growth factor 1; (5) neurotrophin 3; (6) interleukin-17 receptor C; (7) melatonin receptor 1B, and (8) ScoliScore test. Other predictors included: (1) impairment of melatonin signaling in osteoblasts and peripheral blood mononuclear cells (PBMC); (2) G-protein signaling dysfunction in PBMC; and (3) the level of platelet calmodulin. However, predictive values of all these findings were limited, and the levels of evidence were low. The pooled result of brace treatment outcomes demonstrated that around 27% of patents with AIS experienced exacerbation of the spine deformity during or after brace treatment, and 15% required surgical correction. However, the level of evidence is also low due to the limitations of the included studies.

CONCLUSION: This review did not reveal any methods for the prediction of progression in AIS that could be recommended for clinical use as diagnostic criteria.

Low back pain and patient-reported QOL outcomes in patients with adolescent idiopathic scoliosis without corrective surgery

Purpose

To reveal the prevalence of low back pain (LBP) and association between LBP and patient-reported QOL outcomes (JOABPEQ and SRS-22r) in patients with adolescent idiopathic scoliosis (AIS) without corrective surgery.

Methods

Ninety-eight female patients with AIS without corrective surgery who answered JOABPEQ, SRS-22r, and VAS for LBP were included. The scores of all subdomains in JOABPEQ and SRS-22r were calculated. From the standing radiographs, we measured the Risser grade and radiographic parameters regarding the curve magnitude, coronal and sagittal balance, and spinopelvic alignment. Furthermore, we recorded whether the patients were undergoing brace treatment at the time of visiting our outpatient clinic. The patients with VAS >30 mm (moderate or severe LBP) were designated as Group P; VAS ≤30 mm, Group N. All variables were compared between the groups.

Results

The prevalence of LBP (VAS >0 mm) was 34.7% and that of moderate or severe LBP was 16.2%. All subdomain scores in JOABPEQ and those for function and pain in SRS-22r were significantly smaller in Group P than Group N. The subdomain scores for self-image and satisfaction/dissatisfaction with management in SRS-22r did not differ between the groups. The age, Risser grade, radiographic parameters, and whether the patients were undergoing brace treatment did not differ between the groups.

Conclusions

The prevalence of LBP was 34.7%, which was approximately three times higher than that previously reported in Japanese pupils without scoliosis. The patients with LBP demonstrated poorer QOL outcomes associated with LBP regardless of radiographic parameters, patients’ self-image and satisfaction with treatment.

Health-related quality-of-life in adolescent idiopathic scoliosis patients 25 years after treatment

Background

Since 1962 to the mid eighties the Harrington Rod instrumentation was the Golden standard for surgical treatment of Adolescent Idiopathic Scoliosis (AIS). The Boston braces were introduced in the 1970´s and are still used as a conservative treatment, for curves less than 40°. Very few long-term studies exists, focusing on the health related quality of life. The purpose of this study was to evaluate the long-term health related outcome, in a cohort of AIS patients, treated 25 years ago.

Method

219 consecutive patients treated with Boston brace (Brace) or posterior spinal fusion (PSF) using Harrington- DDT instrumentation between 1983 and 1990 at Rigshospitalet Copenhagen, were invited to participate in a long-term evaluation study. A validated Danish version of the Scoliosis Research Society 22R (SRS22R) and Short Form-36 (SF36v1) were administrated to the patients two weeks before the clinical and radiological examination.

Results

159 (72,6 %) patients participated in the clinical follow up and questionnaires, 11 patients participated only in the questionnaires, 8 emigrated, 4 were excluded due to progressive neurological disease and 2 were deceased. The total follow up was 170 patients (83 %), and the average follow up was 24.5 years (22–30 years).

SRS22R domain scores were within the range described as normal for the general population with no statistical difference between the groups except in the Satisfaction domain, where the PSF group had better scores than the braced group.

The SF36 PCS and MCS scores in both AIS cohorts were similar to the scores for the general population.

Conclusion

HRQOLs, as measured by the SRS22R and SF-36, of adult AIS patients treated with Boston brace or PSF during adolescence were similar to the general population. No clinical progression of the deformity has been detected during the 25-year follow up period. The PSF group had a small but statistically significant higher score in the Satisfaction domain compared to the braced group.

Trial registration

S-20110025 Regional Committees on Health Research Ethics for Southern Denmark.

Cervical Spine Compensation in Adolescent Idiopathic Scoliosis

STUDY DESIGN/SETTING

Cross-sectional.

OBJECTIVES

To determine associations between cervical spine alignment and Lenke type for adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

Although the lumbosacral spine and pelvis are standard considerations for evaluation of AIS, few studies have examined cervical spine alignment. These studies did not consider Lenke types upon which treatment decisions are based.

METHODS

Stratified random sampling from 3,654 full-length preoperative lateral films of patients in a multicenter database of surgically treated AIS was done to obtain a representative sample from all Lenke types and thoracic curve modifiers. The C2-C7 sagittal Cobb and C2-C7 sagittal vertical axis (SVA) distances were measured by reviewers unaware of the patient's Lenke classification. C2-C7 sagittal Cobb and C2-C7 SVA among curve types and thoracic modifiers was compared using analysis of variance.

RESULTS

There were 387 females and 84 males among patients in 471 randomly selected films; mean age at surgery was 14.8 ± 2.0 years. Significantly less cervical kyphosis was seen in Lenke 3 or 4 curves and greater cervical kyphosis in Lenke 1, 2, 5, and 6 curves. No significant differences in C2-C7 SVA were seen.

CONCLUSIONS

Patients with AIS appear to compensate for abnormal thoracic sagittal alignment with changes in cervical sagittal alignment. This seems intuitive for Lenke 1 and 2 curves in which surgical restoration of thoracic kyphosis is a recognized goal and has been shown to improve cervical alignment. Cervical kyphosis was also noted in Lenke 5 and 6 curves, which suggests a need to consider compensatory thoracic and cervical sagittal alignment during surgical planning. Patients with Lenke 3 and 4 curves had more normal cervical alignment, which suggests that with the major portion of the curve located in the middle of the spine, there is more ability above and below to maintain a more normal sagittal alignment.

Flatback Revisited: Reciprocal Loss of Lumbar Lordosis Following Selective Thoracic Fusion in the Setting of Adolescent Idiopathic Scoliosis

STUDY DESIGN

Retrospective review of prospective multicenter adolescent idiopathic scoliosis (AIS) database.

OBJECTIVE

To investigate the relationship between iatrogenic loss of thoracic kyphosis (TK) after selective thoracic posterior spinal instrumentation and fusion (PSIF) for AIS with straightening of lumbar lordosis (LL).

SUMMARY OF BACKGROUND DATA

Segmental PSIF has become the standard of care for surgical treatment of severe AIS. Studies show that adults with flattening of TK and LL can develop pain and dysfunction associated with flatback syndrome. Analysis of post-fusion sagittal alignment is lacking in the AIS population.

METHODS

Query of prospective multicenter database for AIS patients with Lenke 1, 2, or 3 curves who underwent selective thoracic PSIF (lowest instrumented vertebra equal or cephalad to L1) identified 123 patients with a minimum of 2 years' follow-up. Thoracic kyphosis (T5-T12), LL (T12-S1), and global sagittal alignment were measured preoperatively and at 2 years postoperatively. Health-related quality of life measures were examined.

RESULTS

A total of 31% of patients had loss of TK and 42% lost LL. Patients with decreased TK had significantly higher rates of decreased LL (68%) than patients without decreased TK (31%). Multivariate regression confirmed that TK had significant predictive effect on LL (p < .001). Specifically, change in TK of 2° was associated with roughly 3° change in LL. There were no significant associations between changes in TK or LL and health-related quality of life.

CONCLUSIONS

Loss of TK occurs commonly in selective fusion for AIS. This loss of kyphosis is strongly associated with reciprocal loss of LL. Spinal fusion can have unintended effects on sagittal alignment; these effects may have consequences that remain to be fully elucidated.

Body Mass Index in Adolescent Spinal Deformity: Comparison of Scheuermann's Kyphosis, Adolescent Idiopathic Scoliosis, and Normal Controls

STUDY DESIGN

Prospective, multicenter study of Scheuermann's kyphosis (SK) and adolescent idiopathic scoliosis (AIS) compared to a control group.

OBJECTIVES

Compare body mass index (BMI) and Scoliosis Research Society Questionnaire-22 (SRS-22) scores among two diagnosis and one control group.

SUMMARY OF BACKGROUND DATA

BMI has been reported as increased in SK patients; however, there are few recent data on this subject or comparing SK to AIS.

METHODS

Ninety-two SK patients (37 female, 55 male, average age 16 years), 1,051 AIS patients (814 female, 237 male, average age 15 years), and 380 adolescents without scoliosis (controls) were compared based on age, gender, race, height (m), weight (kg), BMI, and SRS-22 scores. An analysis of variance was used to test differences in BMI and SRS-22 scores between the groups and between males and females. Pearson correlations determined the relationship between AIS T5-T12 kyphosis and BMI, SK max kyphosis and BMI, and to determine the relationship between BMI and SRS-22 scores in each group.

RESULTS

More SK patients were "obese" and "overweight" (28% and 22%) compared to the AIS (6% and 9%) and Control groups (5.8% and 17.9%) (p < .001). More AIS patients were "underweight" (27%, SK: 13%, Control: 12.1%; p < .03). T5-T12 kyphosis was weakly correlated with BMI (r = 0.17), whereas max kyphosis correlated well with BMI (r = 0.39, p < .00). The SK group had significantly lower (worse) SRS-22 scores than AIS patients in the Pain (3.97 vs. 4.10), Self-Image (2.86 vs. 3.35), Mental Health (3.72 vs. 4.02), and Total Score domains (3.62 vs. 3.92, p < .001). Increased pain scores were weakly correlated with decreasing BMI in all three groups.

CONCLUSIONS

SK patients are at increased risk for elevated BMI and worse SRS-22 scores, indicating that they may suffer from delayed diagnosis and increased surgical complications. AIS patients are at increased risk for issues related to low BMI and should also be monitored.

Cross-Links Do Not Improve Clinical or Radiographic Outcomes of Posterior Spinal Fusion With Pedicle Screws in Adolescent Idiopathic Scoliosis: A Multicenter Cohort Study

STUDY DESIGN

Retrospective, comparative analysis.

OBJECTIVES

Comparative analysis was performed to determine the differences, if any, between adolescent idiopathic scoliosis (AIS) patients who underwent posterior spinal fusion (PSF) with and without cross-links.

SUMMARY OF BACKGROUND DATA

Cross-links are frequently used during PSF for AIS. It is unclear whether they provide any advantage for patients with all-pedicle screw constructs.

METHODS

A prospectively collected multicenter database of patients with AIS undergoing spinal fusion was retrospectively queried. Study inclusion criteria were primary PSF with all-pedicle screw fixation (greater than 90% fixation points) and minimum 2 years' follow-up. Collected data included demographics, radiographic measures, complications, Scoliosis Research Society-22r and Spinal Appearance Questionnaire (SAQ) scores.

RESULTS

A total of 500 patients were included (377 cross-link and 123 non-cross-link). Age, body mass index, gender, and preoperative major Cobb angle were not different between groups. Except for a slightly decreased lumbar Cobb angle (2.7°) in the cross-link group, no other radiographic measures were different at follow-up. Complications were not significantly different between groups: 21 of 377 (6%) crosslink and 9 of 123 (7%) non-cross-link. Infection occurred in 1 patient in the cross-link group and none in the non-cross link group. Reoperation occurred in 4 patients, all with cross-links (3 for implant removal and 1 for distal adding-on). Scoliosis Research Society-22r scores, total and individual domains, improved by a similar amount in both groups. At follow-up, parent and patient SAQ appearance scores were not significantly different. The SAQ expectations domain scores were similar for all visits and improved for both patients and parents.

CONCLUSIONS

There do not appear to be significant clinical or radiographic outcome differences in patients with AIS undergoing PSF based on the use of cross-links at 2-year follow-up. Surgeons should consider eliminating cross-links in patients with AIS who have PSF with all-pedicle screw constructs. This may have substantial cost savings without affecting patient outcome.

Evaluation of motion sickness susceptibility by motion sickness susceptibility questionnaire in adolescents with idiopathic scoliosis: a case-control study

PURPOSE

Adolescent idiopathic scoliosis (AIS) is a three-dimensional deformity of the spine, with unknown origin. Some studies have noted impaired postural balance in AIS, in particular, difficulty to manage situations with sensory conflict. The motion sickness susceptibility can be secondary to a sensory conflict, for example, between visual and vestibular information. Our hypothesis is: patients with AIS have difficulty in managing situations with sensory conflict and therefore have increased motion sickness susceptibility. The purpose of this study was to evaluate in AIS subjects by evaluating their susceptibility to motion sickness, as compared to a control group.

METHODS

We conducted an analysis of data on motion sickness susceptibility collected prospectively from 2012, with the B score of motion sickness susceptibility questionnaire. This evaluation was completed for 65 adolescents (age 14.5 ± 1.6 year) with major right thoracic AIS (Cobb = 40.7° ± 13.1°) and 71 matched controls (14.6 ± 1.6 year).

RESULTS

Adolescents with major right thoracic AIS were more susceptible to motion sickness (B score = 5.3 ± 5.8) than controls (B score = 3.4 ± 3.7) with significant difference (p = 0.025).

CONCLUSIONS

We interpret our results suggesting there is difficulty for patients with AIS to manage situations with sensory conflict. Previous studies focusing on situations with sensory conflict in AIS have required sophisticated technology. They are not accessible for routine patient management. Our research shows the same result with simple, non invasive, low-cost and quick method: B score of motion sickness susceptibility questionnaire.

Adolescent idiopathic scoliosis and spinal fusion do not substantially impact on postural balance

BACKGROUND

The spinal curvature in patients with Adolescent Idiopathic Scoliosis (AIS) causes an asymmetry of upper body postural alignment, which might affect postural balance. However, the currently available studies on balance in AIS patients are not consistent. Furthermore, it is not known whether potential deficits are similar between patients with single and double curves. Finally, the effects of a corrective posterior spinal fusion on postural balance have not yet been well established.

METHODS

Postural balance was tested on a force plate, in 26 female subjects with AIS (12-18 years old; preoperative Cobb-angle: 42-71°; single curve n = 18, double curve n = 6) preoperatively, at 3 months and 1 year postoperatively. We also conducted a balance assessment in 18 healthy age-matched female subjects. Subjects were tested during quiet double-leg standing in four conditions (eyes open/closed; foam/solid surface), while standing on one leg, while performing a dynamic balance (weight shifting) task and while performing a reaching task in four directions.

RESULTS

AIS subjects did not demonstrate greater COP velocities than controls during the double-leg standing tasks. In the reaching task, however, they achieved smaller COP displacements than healthy controls, except in the anterior direction. AIS patients with double curves had significantly greater COP velocities in all test conditions compared to those with a single curve (p < 0.05). For the AIS group, a slight increase in COP velocities was observed in the foam eyes closed and right leg standing condition at 3 months post surgery. At 1-year post surgery, however, there were no significant differences in any of the outcome measures compared to the pre-surgery assessment, irrespective of the curve type.

CONCLUSIONS

Postural balance in AIS patients scheduled for surgery was similar to healthy age matched controls, except for a poorer reaching capacity. The latter finding may be related to their reduced range of motion of the spine. Patients with double curves demonstrated poorer balance than those with a single curve, despite the fact that they have a more symmetrical trunk posture. Postural balance one year after surgery did not improve as a result of the better spinal alignment, neither did the reduced range of trunk motion inherent to fusion negatively affect postural balance.

Current progress in genetic research of adolescent idiopathic scoliosis

Previous genetic linkage analysis and candidate gene association analysis have unveiled dozens of variants associated with the development of adolescent idiopathic scoliosis (AIS), which however can seldom be replicated in different ethnics. Recently, two genome-wide association studies of AIS performed in Japan revealed that ladybird homeobox 1 (LBX1) gene and G protein-coupled receptor 126 (GPR126) gene could play a role in the etiopathogenesis of the disease. Since the association between these two genes and AIS were successfully validated in the Caucasian and the Chinese population, LBX1 gene and GPR126 gene were the most reliable genetic variants underling the development of AIS.

MRI-based morphological evidence of spinal cord tethering predicts curve progression in adolescent idiopathic scoliosis

BACKGROUND CONTEXT

Existing prognostic factors for adolescent idiopathic scoliosis (AIS) patients have focused mainly on curve, maturity, and bone-related factors. Previous studies have shown significant associations between curve severity and morphological evidences of relative shorter spinal cord tethering in AIS, and increased prevalence of abnormal somatosensory cortical-evoked potentials and low-lying cerebellar tonsil in severe AIS. Earlier evidence suggests that there might be neural morphological predictors for curve progression.

PURPOSE

The purpose of this study was to identify any morphological predictors associated with cord tethering, as measured by magnetic resonance imaging (MRI), for curve progression in AIS patients.

STUDY DESIGN/SETTING

This is a prospective cohort study.

PATIENT SAMPLE

A total of 81 female AIS subjects between 10 and 14 years were included, without surgical intervention during the follow-up period.

OUTCOME MEASURES

Magnetic resonance imaging scans of hindbrain and whole spine and areal bone mineral density (BMD) at bilateral femoral necks were performed.

METHODS

All AIS patients were longitudinally followed up starting from initiation of bracing beyond skeletal maturity in 6-month intervals. Clinical and radiographic data were recorded at each clinic visit. Bone mineral density and MRI measurements including ratio of spinal cord to vertebral column length, ratio of anteroposterior (AP) and transverse (TS) diameter of cord, lateral cord space (LCS) ratio, cerebellar tonsil level, and conus medullaris position were obtained at baseline. Only compliant patients with a minimum 2-year follow-up were analyzed. Adolescent idiopathic scoliosis girls were assigned into three groups according to bracing outcome: Group A, nonprogression (curvature increase of less than or equal to 5°); Group B, progression (curvature increase of greater than or equal to 6°); Group C, progression with surgery indication (Cobb angle of greater than or equal to 50° after skeletal maturity despite bracing). The predictors for curve progression were evaluated using univariate analysis and multivariate ordinal regression model.

RESULTS

The average duration of follow-up was 3.4 (range, 2.0-5.6) years. There were 46 girls (57%) in Group A, 19 (23%) in Group B, and 16 (20%) in Group C. No significant intergroup differences were found in spinal cord length, tonsil level, and conus position. Group C had significantly longer vertebral column length, smaller cord-vertebral length ratio, and higher AP/TS cord ratio compared with Group A, whereas LCS ratio in Group C was significantly increased compared with both Group A and Group B. In regression model, five significant independent predictors including cord-vertebral length ratio (odds ratio [OR]: 1.993 [95% confidence interval {CI}: 1.053-3.771], p=.034), LCS ratio (OR: 2.639 [95% CI: 1.128-6.174], p=.025), initial Cobb angle (OR: 1.156 [95% CI: 1.043-1.281], p=.006), menarche age (OR: 1.688 [95% CI: 1.010-2.823], p=.046), and BMD (OR: 2.960 [95% CI: 1.301-6.731], p=.010) and a marginally significant predictor namely AP/TS cord ratio (OR: 1.463 [95% CI: 0.791-2.706], p=.096) were obtained.

CONCLUSIONS

On baseline MRI measurement, cord-vertebral length ratio and LCS ratio are identified as new significant independent predictors for curve progression in AIS, whereas AP/TS cord ratio is suggested as a potential predictor requiring further validations. The earlier MRI parameters can be taken into accounts for prognostication of bracing outcome.