Morphological differences in scoliosis curvatures as a cause of difficulties in its early detection based on angle of trunk inclination

INTRODUCTION

The three dimensional deformation of the spine in scoliosis is specific for a given child with regard to the number and length of curvatures, their degree of rotation and the size of the curvature angle. Early diagnosis of scoliosis in a clinical examination according to the Adams test depends on the correlation between the angle of trunk inclination (ATI) and the Cobb angle and the adopted diagnosis criterion. The aim of the study was to demonstrate the need to adopt different diagnostic criteria for ATI depending on the age and location of scoliosis. Moreover, the observed differences in the ATI/Cobb correlation became the basis for the proposal to introduce the concept of low, medium and high-rotated of curvature to the clinical description of scoliosis.

MATERIALS AND METHODS

The group consisted of 229 children who were first examined, aged 6 to 17 years, with an average age of -11.57 years (SD ± 3.26), with symptoms of idiopathic scoliosis. The correlation of the criteria for the diagnosis of scoliosis in the ATI 7° clinical trial with a Cobb angle of 10° three dimensional in the X-ray image was used to distinguish three types of curvature/scoliosis, i.e., low, medium and high rotation. The frequencies of each type were compiled for three age groups and three scoliosis locations. Moreover, the degree of vertebral rotation according to the Perdriolli (AVR) of curvature was correlated with the Cobb angle and ATI. A one-way logistic regression model was used to assess the effectiveness of scoliosis detection in children based on the measurement of the ATI angle alone and the measurement of both ATI and Cobb angles.

RESULTS

Low-rotated curves were most often found in the age groups of 6-9 and 10-12 years in 65.6% and 71.4% of patients, respectively (p < 0.05). Medium-rotated curvatures were most common in the age group of 13-17 years - 51.6%. With regard to the localization of scoliosis, the low-rotated curvatures were significantly more frequently (p < 0.05) found in the lumbar and thoracolumbar spine. Moreover, the univariate regression model for ATI showed that we could detect scoliosis best by taking the cut-off point of 5° and the mathematically determined Cobb angle was 9.5°. Patients with ATI ≥ 7° had significantly higher AVR values ​​than those with ATI < 7°, and the ATI/AVR correlation was of average strength.

CONCLUSION

The specific morphology of the scoliotic curvature of the child's spine may be manifested by the difference in the ATI/Cobb correlation depending on the location of the scoliosis and change with age. The curvatures of the scoliosis that form can be low, medium and high-rotated, and the low-rotated curvatures were most often found in the 6-9- and 10-12-year-old groups and in the lumbar and thoracolumbar section. To increase the rate of early diagnosis of scoliosis, the results suggest the need to adopt two ATI criteria for the diagnosis of scoliosis at screening, 5° for age of 6-12 years, and when asymmetry affects the lumbar and thoracolumbar section, and 7° for the remaining children.

Associations between facet tropism and vertebral rotation in patients with degenerative lumbar disease

Background

Vertebral rotation and facet tropism are very common in various lumbar degenerative diseases. Facet tropism means the presence of asymmetric angles on both sides of the facet joints. Studies have shown that facet tropism contributes to lumbar degenerative disease, and also inevitably leads to the asymmetry of movement and the imbalance of force, which may be possible to rotate the vertebral body. The aim of this study was to explore the correlation between lumbar vertebral rotation and facet tropism in patients with lumbar degenerative diseases.

Methods

A total of 198 patients with lumbar degenerative diseases from 2018 to 2019 were enrolled. Five hundred and seventy vertebral rotation angles and 1140 facet angles were measured. The vertebral bodies are divided into non-rotation group (Group A) and rotation group (Group B) with the vertebral rotation angle of 3° as the boundary. The information including gender, age, BMI (body mass index), bone mineral density, history of smoking, drinking, hypertension, diabetes, diagnosis, segment distribution, and degree of facet degeneration were also counted. Using inter-class correlation coefficients (ICC) to test the reliability of measurement results. Univariate and multivariate logistic regression analysis were used to analyze the relationship between vertebral rotation and facet tropism.

Results

The consistency of the ICC within the groups of the observers is above 0.8, with good agreement. The results of univariate analysis showed that facet tropism was significantly different between group A and group B (OR (odds ratio)  = 3.30, 95% CI  =  2.03–5.35, P  < 0.0001). Other significant factors were included as adjustment variables into the multivariate regression model. Three models were analyzed separately (Model 1: non-adjusted. Model 2: adjust for age; facet degeneration; Model 3: adjust for age; disease distribution; segment distribution; facet degeneration). The results showed that after adjusting the confounders, the correlation between facet tropism and vertebral rotation did not change (Model 1: OR  = 3.30, 95% CI  = 2.03–5.35, P  < 0.0001; Model 2: adjusted OR  = 2.87, 95% CI  = 1.66–4.97, P  = 0.0002, Model 3: adjusted OR  = 2.84, 95% CI  = 1.56–5.17, P  = 0.0006).

Conclusion

Current research demonstrates that there is an association between vertebral rotation and facet tropism, suggesting that vertebral rotation may also have a certain degree of correlation with lumbar degenerative diseases.

Analysis of apex and transitional vertebra of the spine according to pelvic incidence using orientation and position parameters

OBJECTIVE

To identify the different apex and transitional vertebra according to the shape of the pelvis of individuals despite their difference in sagittal alignment using our measurement system.

METHODS

Full-spine X-rays using EOS in standard stand-position of 99 volunteers were selected (47 women, 52 men, mean age 31 years old). Validated 3D reconstruction technique allows extraction of spinopelvic parameters, and position and rotation of each vertebra and lumbar disks. Subjects were divided into three groups: low PI (lowPI, n = 37), moderate PI (midPI, n = 52), high PI (highPI, n = 10), with, respectively, a PI below 45°, between 45° and 60° and above 60°. Occurrence of specific position and rotation values of apex and transitional vertebra were assessed in each group.

RESULTS

Frequency curves tend to move cranially when the incidence increases except in cervicothoracic where T1 is a constant for all shapes of spine with occurrence approaching 90%. Angulation value of relevant vertebra and lumbar lordosis are significantly positively correlated for the whole population.

CONCLUSIONS

Our study allowed the assessment of the distribution of spine curvatures according to the pelvic incidence. It describes the occurrence of localization of the apex and transitional vertebrae according to pelvic incidence. These results should be taken into account during the analysis of the sagittal balance, especially when planning deformity surgery in adults.

The rotation of preoperative-presumed lowest instrumented vertebra: Is it a risk factor for distal adding-on in Lenke 1A/2A curve treated with selective thoracic fusion?

PURPOSE

To investigate whether the rotation of preoperative-presumed lowest instrumented vertebra (LIV) is a risk factor for adding-on (AO) in adolescent idiopathic scoliosis (AIS) treated with selective posterior thoracic fusion (sPTF).

METHODS

A total of 196 AIS patients of Lenke type 1A or 2A with minimum 2-year follow-up after sPTF with all pedicle screw instrumentation were included. Radiographical parameters were measured as follows: preoperative rotation angle of presumed LIV and LIV + 1, LIV + 1/LIV rotation difference, postoperative rotation angle of LIV and LIV derotation angle on CT scans. Patients were classified into AO group and non-AO group during the follow-up. The parameters were compared between the two groups to investigate risk factors for AO.

RESULTS

Among 196 patients, 40 (20.4%) patients developed with AO at the final follow-up. Compared with non-AO group, patients with AO had significantly larger preoperative rotation angle of presumed LIV (8.8° ± 3.4° vs. 3.4° ± 2.9°, P < 0.001) and LIV + 1 (5.9° ± 4.0° vs. 3.6° ± 2.9°, P = 0.004), LIV + 1/LIV rotation difference (- 2.6° ± 3.7° vs. 0.6° ± 3.2°, P < 0.001) and postoperative rotation angle of LIV (7.2° ± 4.3° vs. 3.0° ± 2.9°, P < 0.001). The last substantially touched vertebrae (LSTV) was selected as LIV in 148 patients, among which the above described parameters were found to be remarkably larger in AO group than non-AO group as well. Multivariate analysis presented Risser grade and preoperative rotation angle of presumed LIV as independent predictors of AO.

CONCLUSION

AIS patients with low Risser grade and large preoperative rotation angle of presumed LIV are more likely to develop with AO after sPTF. Moreover, for the patients with LSTV selected as LIV, preoperative rotation of presumed LIV might be still a risk factor associated with the occurrence of AO.

LEVEL OF EVIDENCE

III These slides can be retrieved under Electronic Supplementary Material.

An Application of Artificial Intelligence to Diagnostic Imaging of Spine Disease: Estimating Spinal Alignment From Moiré Images

The use of artificial intelligence (AI) as a tool supporting the diagnosis and treatment of spinal diseases is eagerly anticipated. In the field of diagnostic imaging, the possible application of AI includes diagnostic support for diseases requiring highly specialized expertise, such as trauma in children, scoliosis, symptomatic diseases, and spinal cord tumors. Moiré topography, which describes the 3-dimensional surface of the trunk with band patterns, has been used to screen students for scoliosis, but the interpretation of the band patterns can be ambiguous. Thus, we created a scoliosis screening system that estimates spinal alignment, the Cobb angle, and vertebral rotation from moiré images. In our system, a convolutional neural network (CNN) estimates the positions of 12 thoracic and 5 lumbar vertebrae, 17 spinous processes, and the vertebral rotation angle of each vertebra. We used this information to estimate the Cobb angle. The mean absolute error (MAE) of the estimated vertebral positions was 3.6 pixels (~5.4 mm) per person. T1 and L5 had smaller MAEs than the other levels. The MAE per person between the Cobb angle measured by doctors and the estimated Cobb angle was 3.42°. The MAE was 4.38° in normal spines, 3.13° in spines with a slight deformity, and 2.74° in spines with a mild to severe deformity. The MAE of the angle of vertebral rotation was 2.9°±1.4°, and was smaller when the deformity was milder. The proposed method of estimating the Cobb angle and AVR from moiré images using a CNN is expected to enhance the accuracy of scoliosis screening.

Vertebral Axial Asymmetry in Adolescent Idiopathic Scoliosis

STUDY DESIGN

Retrospective study.

OBJECTIVES

To investigate parameters of axial vertebral deformation in patients with scoliosis compared to a control group, and to determine whether these parameters correlated with the severity of spine curvature, measured as the Cobb angle.

SUMMARY OF BACKGROUND DATA

Adolescent idiopathic scoliosis (AIS) is the most common type of spinal deformity. Many studies have investigated vertebral deformation, in terms of wedging and pedicle deformations, but few studies have investigated actual structural changes within vertebrae.

METHODS

This study included 20 patients with AIS (Lenke 1-3, mean age: 15.6 years, range: 11-20). We compared preoperative low-dose computed tomography (CT) examinations of patients with AIS to those of a control group matched for age and sex. The control individuals had no spinal deformity, but they were admitted to the emergency department for trauma CTs. We measured the Cobb angles and the axial vertebral rotation (AVR), axial vertebral body asymmetry (AVBA), and frontal vertebral body rotation (FVBR) for the superior end, inferior end, and apical vertebrae, with in-house-developed software. Correlations between entities were investigated with the Pearson correlation test.

RESULTS

The average Cobb angles were 49.3° and 1.3° for the scoliotic and control groups, respectively. The patient and control groups showed significant differences in the AVRs of all three vertebra levels (p < .01), the AVBAs of the superior end and apical vertebrae (p < .008), and the FVBR of the apical vertebra (p = .011). Correlations were only found between the AVBA and FVBR in the superior end vertebra (r = 0.728, p < .001) and in the apical vertebra (r = 0.713, p < .001).

CONCLUSIONS

Compared with controls, patients with scoliosis showed clear morphologic differences in the midaxial plane vertebrae. Differences in AVR, AVBA, and FVBR were most pronounced at the apical vertebra. The FVBR provided valuable additional information about the internal rotation and deformation of vertebrae.

LEVEL OF EVIDENCE

Level III.

[Similar coronal curvature may not represent the same 3-dimensional deformity in adolescent idiopathic scoliosis: a matched-pair study using EOS imaging system]

Objective: To analyze the preoperative axial plane and the surgical outcomes of the Lenke type 1A patients with adolescent idiopathic scoliosis (AIS) whose coronal curve type was matched but thoracic kyphosis (TK) was different. Methods: This study retrospectively reviewed a series of Lenke type 1A female AIS patients who underwent corrective surgery in the Department of Spine Surgery of Nanjing Drum Tower Hospital from May to August 2017. After matched with the Cobb angle of the main thoracic curve, the apical vertebral, the vertebra number included in the curve, the lumber modifier in the Lenke classification and Risser sign, 12 pairs of AIS patients, whose coronal curve was matched but thoracic kyphosis was different, were included in this study. The patients were divided into normal TK group and thoracic hypokyphosis group. EOS whole-body images were taken preoperatively and reconstructed by three-dimensional reconstruction. The whole spine anteroposterior X-ray was taken at 3 weeks after surgery. The radiographic parameters were measured on the preoperative and postoperative two-dimensional X-ray images: coronal Cobb angle, TK, lumbar lordosis (LL), pelvic incidence (PI) and pelvic tilt (PT). The vertebra rotation was obtained on the EOS three-dimensional reconstructed image, and the average vertebral rotation of the major thoracic curve (MTR), the average vertebral rotation of the proximal thoracic curve (PTR) and the average vertebral rotation of the lumbar curve (LR) were calculated. The paired sample t test was used to compare the difference of preoperative and postoperative radiographic parameters between the groups. Results: A total of 24 patients (12 pairs) were included in this study with an average age of (13.7±2.9) years. The preoperative Cobb angle was similar in the two groups (53.8°±10.2° vs 51.0°±11.1°, t=0.27, P=0.81). The average preoperative TK of the normal TK groups was 28.2°±6.1°, while that of the thoracic hypokyphosis group was 11.2°±5.6°(t=7.68, P<0.01). The MTR in the normal TK group was significantly smaller than that in the thoracic hypokyphosis group (10.2° vs 12.7°, t=-3.74, P<0.01), and there was a significant correlation between TK and MTR (r=0.30, P=0.03). As for the lumbar curve rotation, the LR of the normal TK group was significantly smaller than that in the thoracic hypokyphosis group (t=-2.65, P=0.002), but the absolute value of the two groups was similar (t=-0.33, P=0.31). The lumbar Cobb angle correction rate was significantly greater in patients with thoracic and lumbar curve rotating in the same direction than that in the opposite direction (81.1% vs 61.9%, t=4.24, P=0.005). Conclusions: It indicated that when the coronal deformity is matched, the MTR of the patients with thoracic hypokyphosis is significantly larger than that in the patients with normal thoracic kyphosis. The direction of the thoracic and lumbar curve rotation is required to be well concerned in the preoperative surgical planning.

Triplanar correction of adolescent idiopathic scoliosis by asymmetrically shaped and simultaneously applied rods associated with direct vertebral rotation: clinical and radiological analysis of 36 patients

PURPOSE

Aim of this study was to investigate the effectiveness of a new surgical corrective manoeuvre for adolescent idiopathic scoliosis (AIS) by asymmetrically shaped and simultaneously applied rods and in combination with direct vertebral rotation, to control both the triplanar deformity and the kyphosis apex location.

METHODS

We retrospectively reviewed 36 patients who undergo surgical treatment using simultaneous translation on two differently contoured rods, in combination with direct vertebral rotation. Patients were divided into three main groups according to the scoliotic curve type.

RESULTS

The average follow-up was 1.8 years (range 1-3 years). Mean thoracic Cobb angle decreased from 64.6° to 17.0 (p < 0.05). Mean lumbar Cobb angle decreased from 54.9 to 13°. T5-T12 kyphosis values improved from 16.2 to 22.8° (p < 0.05). Apical vertebral rotation decreased from 25.3 to 9.7°. Mean total SRS-22 score values improved from 2.3 on pre-operative to 3.8 at the last available follow-up. Two major and two minor perioperative complications were recorded. Nor deformity progression or screw pull-out or non-union was recorded at the last available follow-up.

CONCLUSIONS

The corrective manoeuvre using two differently contoured rods simultaneously in combination with direct vertebral rotation can provide a good triplanar deformity correction and improve patient's quality of life and self-image perception in mild-to-moderate AIS. Moreover, the described technique allows the positioning of the desired kyphosis apex at a different level from the scoliosis apex. This procedure allows a better sagittal contour restoration while maintaining a comparable amount of correction on the frontal and axial plane of the already available techniques. These slides can be retrieved under Electronic Supplementary Material.

Development and assessment of a digital X-ray software tool to determine vertebral rotation in adolescent idiopathic scoliosis

BACKGROUND CONTEXT

The amount of vertebral rotation in the axial plane is of key importance in the prognosis and treatment of adolescent idiopathic scoliosis (AIS). Current methods to determine vertebral rotation are either designed for use in analogue plain radiographs and not useful in digital images, or lack measurement precision and are therefore less suitable for the follow-up of rotation in AIS patients.

PURPOSE

This study aimed to develop a digital X-ray software tool with high measurement precision to determine vertebral rotation in AIS, and to assess its (concurrent) validity and reliability.

STUDY DESIGN/SETTING

In this study a combination of basic science and reliability methodology applied in both laboratory and clinical settings was used.

METHODS

Software was developed using the algorithm of the Perdriolle torsion meter for analogue AP plain radiographs of the spine. Software was then assessed for (1) concurrent validity and (2) intra- and interobserver reliability. Plain radiographs of both human cadaver vertebrae and outpatient AIS patients were used. Concurrent validity was measured by two independent observers, both experienced in the assessment of plain radiographs. Reliability-measurements were performed by three independent spine surgeons.

RESULTS

Pearson correlation of the software compared with the analogue Perdriolle torsion meter for mid-thoracic vertebrae was 0.98, for low-thoracic vertebrae 0.97 and for lumbar vertebrae 0.97. Measurement exactness of the software was within 5° in 62% of cases and within 10° in 97% of cases. Intraclass correlation coefficient (ICC) for inter-observer reliability was 0.92 (0.91-0.95), ICC for intra-observer reliability was 0.96 (0.94-0.97).

CONCLUSIONS

We developed a digital X-ray software tool to determine vertebral rotation in AIS with a substantial concurrent validity and reliability, which may be useful for the follow-up of vertebral rotation in AIS patients.

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.

Osteoid osteoma presenting as thoracic scoliosis

BACKGROUND CONTEXT

Osteoid osteoma of the thoracic spine is relatively uncommon and is often difficult to diagnose, especially when patients do not complain of pain.

PURPOSE

This study aims to describe an unusual case of scoliosis caused by osteoid osteoma of the thoracic spine that was challenging to diagnose.

STUDY DESIGN/SETTING

A case report of a 12-year-old girl who presented with scoliosis caused by osteoid osteoma of the thoracic spine without apparent pain was carried out.

METHODS

Diagnosis of the lesion was made using computed tomography (CT) and magnetic resonance imaging as well as the Scoliosis Research Society-22 (SRS-22) patient-based questionnaire.

RESULTS

A preoperative CT myelogram revealed a mass lesion in the lamina of the 10th thoracic vertebra that was considered to be osteoid osteoma. This diagnosis was histologically confirmed following tumor excision. The patient's spinal deformity and SRS-22 scores were both improved at 5 months postoperatively.

CONCLUSIONS

Osteoid osteoma of the thoracic spine may present as non-painful scoliosis. Tumor resection is effective. Clinicians should bear this uncommon lesion in mind during recommended CT examination before scoliosis surgery.

Intra- and Interobserver Reliability of the Cobb Angle-Vertebral Rotation Angle-Spinous Process Angle for Adolescent Idiopathic Scoliosis

STUDY DESIGN

A reliability analysis of Cobb angle, vertebral rotation (VR), and spinous process angle (SPA) measurements in adolescent idiopathic scoliosis.

OBJECTIVE

To determine the intra- and interobserver reliability of semi-automated digital radiograph measurements.

SUMMARY OF BACKGROUND DATA

Cobb angle measurements on posteroanterior radiographs are commonly used to determine the severity of scoliosis. Vertebral rotation helps assess scoliosis 3-dimensionally and has a role in predicting curve progression. Recent studies have shown that the spinous process angle is a useful parameter in assessing scoliosis when using ultrasound imaging. Because the reliability of SPA measurements on radiographs has yet to be determined, it is important to compare the reliability of these 3 parameters (Cobb angle, VR, and SPA) using a computer assisted semi-automated method.

METHODS

Sixty posteroanterior radiographs of patients with adolescent idiopathic scoliosis were obtained and measured twice by 3 observers who were blinded to their previous measurements, using an in-house developed program. Measurements were obtained using a semi-automated method to minimize variability resulting from observer reliability. The intra- and interobserver reliabilities were analyzed using intra-class correlation coefficients (ICCs) as well as Bland-Altman's bias and limits of agreement.

RESULTS

Over 350 (intra) and 90 (inter) sets of curves with an average Cobb angle of 26° ± 9° (range, 10° to 44°) were compared for each parameter. Intra-observer reliabilities for each parameter were excellent (ICC_[2,1], .82; 1.00), with mean absolute differences under 3° between most measurements. Interobserver reliability (ICC_[2,1], .72; .95) was mostly good to excellent, with mean absolute differences ranging from 2.0° to 5.6°.

CONCLUSIONS

Both the intra- and interobserver assessment of the Cobb, VR, and SPA from the semi-automated measurements had clinically acceptable reliability ranges and may be considered for clinical implementation. Additional studies will be conducted to determine the accuracy and sensitivity to change of these scoliosis severity measurements.