Monitoring of Curve Progression in Patients with Adolescent Idiopathic Scoliosis Using 3-D Ultrasound

OBJECTIVE

The aim of the work described here was to determine whether 3-D ultrasound can provide results comparable to those of conventional X-ray examination in assessing curve progression in patients with adolescent idiopathic scoliosis (AIS).

METHODS

One hundred thirty-six participants with AIS (42 males and 94 females; age range: 10-18 y, mean age: 14.1 ± 1.9 y) with scoliosis of different severity (Cobb angle range: 10º- 85º, mean: of 24.3 ± 14.4º) were included. Each participant underwent biplanar low-dose X-ray EOS and 3-D ultrasound system scanning with the same posture on the same date. Participants underwent the second assessment at routine clinical follow-up. Manual measurements of scoliotic curvature on ultrasound coronal projection images and posterior-anterior radiographs were expressed as the ultrasound curve angle (UCA) and radiographic Cobb angle (RCA), respectively. RCA and UCA increments ≥5º represented a scoliosis progression detected by X-ray assessment and 3-D ultrasound assessment, respectively.

RESULTS

The sensitivity and specificity of UCA measurement in detecting scoliosis progression were 0.93 and 0.90, respectively. The negative likelihood ratio of the diagnostic test for scoliosis progression by the 3-D ultrasound imaging system was 0.08.

CONCLUSION

The 3-D ultrasound imaging method is a valid technique for detecting coronal curve progression as compared with conventional radiography in follow-up of AIS. Substituting conventional radiography with 3-D ultrasound is effective in reducing the radiation dose to which AIS patients are exposed during their follow-up examinations.

Assessing progressive changes in axial plane vertebral deformity in adolescent idiopathic scoliosis using sequential magnetic resonance imaging

PURPOSE

To understand how the axial plane deformity contributes to progression of the three-dimensional spinal deformity of Adolescent Idiopathic Scoliosis (AIS), with a main thoracic curve type, using a series of sequential magnetic resonance images (MRI).

METHODS

Twenty-seven AIS patients (at scan 1: mean 12.4 years (± 1.5), mean Cobb angle 29.1°(± 8.8°)) had 3 MRI scans (T4-L1) performed at intervals of mean 0.7 years (± 0.4). The outer profile of the superior and inferior endplates were traced on a reformatted axial image using ImageJ (NIH). Endplate AVR, and intravertebral rotation (IVR), defined as the difference between superior and inferior endplate AVR, was calculated for each vertebral level.

RESULTS

For all patients and scans, the mean AVR was greatest at the curve apex, with AVR diminishing in a caudal and cephalic direction from the apex. At scan 3 the mean apical AVR was 15.1°(± 4.6°) with a mean change in apical AVR between MRI 1 and 3 of 2.7°(± 2.9°). The increase in standing height between MRI 1 and 3 was mean 7.4 cm (± 4.6). Linear regression showed a positive correlation between apical AVR and Cobb angle (R2 = 0.57, P < 0.001), and a positive correlation between apical AVR and rib hump (R2 = 0.54, p < 0.001). The mean change in IVR was greater 3 vertebral levels cephalic and caudal to the apex (1.4°(± 4.1°) and 1.2°(± 2.0°), respectively), compared to the apex (0.4°(± 3.1°)).

CONCLUSIONS

AVR increased, during curve progression, most markedly at the curve apex. The greatest IVR was observed at the periapical levels, with the apex by contrast having only a modest degree of rotation, suggesting the periapical vertebral levels of the scoliosis deformity may be a significant driver in the progression of AIS.

Feeding tube use is associated with severe scoliosis in patients with cerebral palsy and limited ambulatory ability

PURPOSE

Cerebral palsy (CP) is the most common motor disorder in childhood. Scoliosis is a common complication of CP that can reach clinically severe levels, but predictors for scoliosis in CP are not well understood. Some variables identified in the literature involve the severity of the brain injury and the presence of hip deformity. We aimed to identify associations with developing severe scoliosis in a prospective cohort of patients with cerebral palsy at higher risk for severe curve progression.

METHODS

This study reviewed a prospectively collected database at a tertiary children's hospital. We evaluated a panel of potential associations with severe scoliosis-including age, sex, Gross Motor Function Classification System (GMFCS) class, history of hip surgery, epilepsy, and feeding tube presence-in a population of children with limited ambulatory ability defined as GMFCS level IV or V CP. Univariate analysis and multivariate logistic regression with stepwise selection was used for analysis.

RESULTS

Descriptive analysis showed that female sex, higher GMFCS class, history of hip surgery, non-upright seating, pelvic obliquity, presence of epilepsy, and presence of a feeding tube were associated with an increased risk for scoliosis. Multivariate logistic regression analysis revealed that the presence of a feeding tube was associated with severe scoliosis even when controlling for GMFCS and age.

CONCLUSIONS

Feeding tube use may stratify risk for severe scoliosis progression in patients with GMFCS IV or V CP.

Evaluation of night-time bracing efficacy in the treatment of adolescent idiopathic scoliosis: a systematic review

STUDY DESIGN

Systematic review of the literature.

PURPOSE

To systematically review the literature to assess the efficacy of night-time bracing in controlling curve progression with respect to traditional full-time thoraco-lumbo-sacral orthoses (TLSOs) in patient with adolescent idiopathic scoliosis.

METHODS

PubMed, Ovid, Cochrane Reviews and Google Scholar were all accessed and a combination of terms and keywords pertaining to the core concept was used in the research. Case reports, technical notes, instructional courses, literature reviews, biomechanical and/or in vitro studies were all excluded, as well as case series (level IV studies). The methodological quality of the selected articles was assessed using the MINORS methodology score. Given the overall level and quality of the available evidence, conclusions were drawn based on a summary of the evidence.

RESULTS

Seven studies were included. Five papers reported no differences in curve progression between traditional TLSOs and night-time braces and the remaining two studies reported TLSO to be superior.

CONCLUSION

The current available literature does not permit us to draw conclusions about night-time braces. The low methodological quality of the studies examined makes it impossible to compare the effectiveness of the night-time braces with that of traditional TLSOs. Prospective well-designed clinical trials applying SRS inclusion and evaluation criteria are mandatory to better define the role of night-time orthosis in the treatment of adolescent idiopathic scoliosis.

Sequential MRI reveals vertebral body wedging significantly contributes to coronal plane deformity progression in adolescent idiopathic scoliosis during growth

STUDY DESIGN

Cross-sectional study.

OBJECTIVES

To provide a comprehensive, multi-stage investigation of vertebral body (VB) and intervertebral disc (IVD) coronal plane deformities for adolescent idiopathic scoliosis (AIS) patients with a main thoracic curve type, using a series of sequential magnetic resonance images (MRIs). Despite numerous investigations of AIS deformity at the spinal segmental level, there is little consensus as to the major contributor to the lateral curvature of a scoliotic spine. Moreover, scoliotic deformity is often described along a continuum of progression, with few studies having characterised the change in segmental deformity for AIS patients whose deformity progresses clinically over time.

METHODS

30 female AIS patients with primary thoracic curves were included between 2012 and 2016. Three sequential MRIs were captured for each patient. Datasets were reformatted to produce true coronal plane images of the thoracic spine (T4-L1). Overall curve morphology, coronal plane IVD and VB segmental deformity and rates of growth were analysed.

RESULTS

Right-side asymmetry was greater in IVDs (18.5 ± 23.9%) when compared to VBs (8.3 ± 9.2%) (P < 0.05) by third scans. Despite this, 77% of patients demonstrated the majority (> 50%) of their coronal curvature was attributed to VB wedging when measured across all three scans. Regardless of progression status, scan number, or region, the sum of the VB wedging angle was greater than the sum of the IVD wedging angle (all P ≤ 0.05). There was no correlation between the rates of major curve angle progression and standing height increase, VB height growth, or IVD height growth (P > 0.05).

CONCLUSIONS

VB wedging contributed more to the lateral deformity observed in primary thoracic subtypes of AIS patients than IVD wedging. While IVDs demonstrated the greatest asymmetric deformity, their relatively smaller height resulted in a smaller proportional change in lateral curve angle compared to the VBs.

LEVEL OF EVIDENCE

IV.

Gravity-induced coronal plane joint moments in adolescent idiopathic scoliosis

Background

Adolescent Idiopathic Scoliosis is the most common type of spinal deformity, and whilst the isk of progression appears to be biomechanically mediated (larger deformities are more likely to progress), the detailed biomechanical mechanisms driving progression are not well understood. Gravitational forces in the upright position are the primary sustained loads experienced by the spine. In scoliosis they are asymmetrical, generating moments about the spinal joints which may promote asymmetrical growth and deformity progression. Using 3D imaging modalities to estimate segmental torso masses allows the gravitational loading on the scoliotic spine to be determined. The resulting distribution of joint moments aids understanding of the mechanics of scoliosis progression.

Methods

Existing low-dose CT scans were used to estimate torso segment masses and joint moments for 20 female scoliosis patients. Intervertebral joint moments at each vertebral level were found by summing the moments of each of the torso segment masses above the required joint.

Results

The patients’ mean age was 15.3 years (SD 2.3; range 11.9–22.3 years); mean thoracic major Cobb angle 52^° (SD 5.9^°; range 42–63^°) and mean weight 57.5 kg (SD 11.5 kg; range 41–84.7 kg). Joint moments of up to 7 Nm were estimated at the apical level. No significant correlation was found between the patients’ major Cobb angles and apical joint moments.

Conclusions

Patients with larger Cobb angles do not necessarily have higher joint moments, and curve shape is an important determinant of joint moment distribution. These findings may help to explain the variations in progression between individual patients. This study suggests that substantial corrective forces are required of either internal instrumentation or orthoses to effectively counter the gravity-induced moments acting to deform the spinal joints of idiopathic scoliosis patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13013-015-0060-9) contains supplementary material, which is available to authorized users.

Segmental torso masses in adolescent idiopathic scoliosis

BACKGROUND

Adolescent idiopathic scoliosis is the most common type of spinal deformity whose aetiology remains unclear. Studies suggest that gravitational forces in the standing position play an important role in scoliosis progression, therefore anthropometric data is required to develop biomechanical models of the deformity. Few studies have analysed the trunk by vertebral level and none have performed investigations of the scoliotic trunk. The aim of this study was to determine the centroid, thickness, volume and estimated mass, for sections of the scoliotic trunk.

METHODS

Existing low-dose CT scans were used to estimate vertebral level-by-level torso masses for 20 female adolescent idiopathic scoliosis patients. ImageJ processing software was used to analyse the CT images and enable estimation of the segmental torso mass corresponding to each vertebral level.

FINDINGS

The patients' mean age was 15.0 (SD 2.7) years with mean major Cobb angle of 52 (SD 5.9)° and mean patient weight of 58.2 (SD 11.6) kg. The magnitude of torso segment mass corresponding to each vertebral level increased by 150% from 0.6kg at T1 to 1.5kg at L5. Similarly, segmental thickness from T1-L5 increased inferiorly from a mean 18.5 (SD 2.2) mm at T1 to 32.8 (SD 3.4) mm at L5. The mean total trunk mass, as a percentage of total body mass, was 27.8 (SD 0.5) % which was close to values reported in previous literature.

INTERPRETATION

This study provides new anthropometric reference data on segmental (vertebral level-by-level) torso mass in adolescent idiopathic scoliosis patients, useful for biomechanical models of scoliosis progression and treatment.