Accuracy and repeatability of a new method for measuring scoliosis curvature

Three-Dimensional Spinal Evaluation Using Rasterstereography in Patients with Adolescent Idiopathic Scoliosis: Is It Closer to Three-Dimensional or Two-Dimensional Radiography?

(1) Background: Adolescent Idiopathic Scoliosis (AIS) is a three-dimensional (3D) spine deformity. The Cobb angle, evaluated with 2D radiography, is the gold standard to determine curve severity. The primary aim of this study was to evaluate the 3D spinal evaluation with rasterstereography in patients with AIS. The hypothesis was that rasterstereography reached higher accuracy than the gold standard 2D radiography. The second aim was to compare rasterstereography with 3D radiography. The hypothesis was that the rasterstereographic evaluation of patients with severe major scoliosis curves is closer to 3D radiography compared to the gold standard (2D radiography). (2) Methods: This is a prospective comparative study of a consecutive series of 53 patients, with the scoliosis curve evaluated with two 3D methods and the gold standard (2D radiography). (3) Results: The hypothesis that rasterstereography reached higher accuracy than the gold standard 2D radiography was validated for all curves. Even if all curves were highly correlated, both rasterstereography and 2D radiography scoliosis evaluation were underestimated for moderate/severe curves compared to 3D radiography. (4) Conclusions: The rasterstereographic evaluation of major curve scoliosis is not accurate enough to replace 2D radiography for moderate/severe curves. A longitudinal follow-up should be assessed in future studies to define the sensitivity of the detection of a significant change in the scoliotic mild and moderate curve (<40°).

Spino-pelvic radiological parameters: Comparison of measurements obtained by radiologists using the traditional method versus spine surgeons using a semi-automated software (Surgimap)

Background

Spinopelvic balance measurement is a key point to get an appropriate diagnosis and treatment in a group of spine pathologies; thus, it seems necessary the evaluation of different methods for obtaining the most reliable values. For that reason, different automatic and semi-automatic computer-assisted tools have been developed, and one example of them is Surgimap.

Purpose

To demonstrate that the sagittal balance measurements with Surgimap are equal and more time-efficient than with Agfa-Enterprise.

Material and Methods

Retrospective-prospective study. Biased comparative analysis of radiographic measurements performed on two different occasions (96 h interval), between two spine surgeons using Surgimap and two radiologists using the traditional Cobb method (TCM) with the Agfa-Enterprise program in 36 full spine lateral X-ray, determining inter- and intra-observer reliability and the mean time required to obtain the measurements.

Results

Measurements with both methods demonstrated an excellent intra-observer correlation (Surgimap: PCC 0.95 [0.85-0.99]; TCM: PCC 0.90 [0.81-0.99]). Inter-observer correlation also demonstrated an excellent relationship (PCC >0.95). Thoracic kyphosis (TK) demonstrated the lowest levels of inter-observer correlation (PCC: 0.75). The average time in seconds with TCM was 154.6, while with the Surgimap it was 41.8 s.

Conclusion

Surgimap proved to be equally reliable and 3.5 times faster. Therefore, in consistency with the available literature, our results would allow us to promote the use of Surgimap as a clinical diagnostic tool considering precision and efficiency.

Assessing clinical trunk change with surface topography: anterior scoliosis correction as a model to evaluate curve progression

PURPOSE

Previous work has suggested that surface topography can be used for repeated measurements of deformity during curve monitoring following an initial radiograph. Changes in deformity during natural curve progression may be subtle. An important preemptive question to answer is whether topography can follow a large change in spine deformity, as in scoliosis correction. We assess the ability of surface topography to track the evolution of spine deformity during anterior scoliosis correction relative to traditional radiographs. Anterior scoliosis correction was chosen for this analysis because it changes the shape of the trunk without leaving a surgical scar and muscle atrophy along the posterior spine.

METHODS

Following IRB approval, 18 patients aged 14.6 ± 2.0 years at surgery were enrolled in a retrospective review of coronal radiographs and topographic scans acquired before and after scoliosis correction. Radiographic and topographic measures for the coronal curve angle before and after surgery were compared.

RESULTS

Surface topography estimates correlate with radiographic measures of the pre- (r = 0.7890, CI = [0.4989 0.9201], p < 0.00001), postsurgical (r = 0.7485, CI = [0.4329 0.9006], p = 0.0004), and the change in the coronal curve angle (r = 0.6744, CI = [0.3028 0.8680], p = 0.0021) due to surgery.

CONCLUSIONS

We provide evidence open for further extension that topography can follow changes in the coronal curve angle comparably to radiographs.

LEVEL OF EVIDENCE

Level IV.

A Novel Computer-Aided Method to Evaluate Scoliosis Curvature using Polynomial Math Function

Background:

Scoliosis is a health problem that causes a side-to-side curvature in the spine. The curvature may have an “S” or “C” shape. To evaluate scoliosis, the Cobb angle has been commonly used. However, digital image processing allows the Cobb angle to be obtained easily and quickly, several researchers have determined that Cobb angle contains high variations (errors) in the measurements. Therefore, a more reproducible computer aided-method to evaluate scoliosis is presented.

Material and Methods:

In this analytical study, several polynomial curves were fitted to the spine curvature (4^th to 8^th order) of thirty plain films of scoliosis patients to obtain the Curvature-Length of the spine. Each plain film was evaluated by 3 physician observers. Curvature was measured twice using the Cobb method and the proposed Curvature-Length Technique (CLT). Data were analyzed by a paired-sample Student t-test and Pearson correlation method using SPSS Statistics 25.

Results:

The curve of 7^th order polynomial had the best fit on the spine curvature and was also used for our proposed method (CLT) obtaining a significant positive correlation when compared to Cobb measurements (r=0.863, P<0.001). The Intraclass Correlation (ICC) was between 0.863 and 0.948 for Cobb method and0.974 to 0.984 for CLT method. In addition, mean measurement of the inter-observer COV (Coefficient of Variation) for Cobb method was of 0.185, that was significantly greater than the obtained with CLT method of 0.155, this means that CLT method is 16.2% more repeatable than Cobb Method.

Conclusion:

Based on results, it was concluded that CLT method is more reproducible than the Cobb method for measuring spinal curvature.

An ontology-based module of the information system ScolioMedIS for 3D digital diagnosis of adolescent scoliosis

BACKGROUND AND OBJECTIVE

Conventional information systems are built on top of a relational database. The main weakness of these systems is impossibility to define stable data schema ahead when the knowledge of the system is evolving and dynamic. The widely accepted alternatives to relational databases are ontologies that can be used for designing information systems. Many research papers describe various methods for improving reliability and precision in generating the type of the Lenke classification based on the image processing techniques or a computer program, but all of them require radiograph images. The main objective of this paper is to demonstrate the development of an ontology-based module of the information system ScolioMedIS for adolescent idiopathic scoliosis (AIS) diagnosis and monitoring, which uses optical 3D methods to determine the Lenke classification of AIS and to avoid harmful effects of traditional radiation diagnosis.

METHODS

For creating an ontology-based module of the ScolioMedIS we used the following steps: specification, conceptualization, formalization and implementation. In the specification and conceptualization phase we performed data collection and analysis to define domain, concepts and relationships for ontology design. In the formalization and implementation stage we developed the OBR-Scolio ontology and the ontology-based module of the ScolioMedIS. The module employs the Protégé-OWL API, as a collection of Java interfaces for the OBR-Scolio ontology, which enables the creating, deleting, and editing of the basic elements of the OBR-Scolio ontology, as well as the querying of the ontology.

RESULTS

The ontology-based module of ScolioMedIS is tested on the datasets of 20 female and 15 male patients with AIS between the ages of 11 and 18, to categorize spinal curvatures and to automatically generate statistical indicators about the frequency of the basic spinal curvatures, degree of progression or regression of deformity and statistical indicators about curvature characteristics according to the Lenke classification system and Lenke scoliosis types. Results are then compared with analysis of the Lenke classification of 315 observed patients, performed using traditional radiation techniques.

CONCLUSIONS

This part of the system allows continuous monitoring of the progression/regression of spinal curvatures for each registered patient, which may provide a better management of scoliosis (diagnosis and treatment).

Video rasterstereography of the spine and pelvis in eight erect positions: A reliability study

INTRODUCTION

To investigate the reliability and variability of Video Rasterstereography (VR) measurements of the spine and pelvis, for eight proposed standing postures, in order to help define an optimal standing position for erect pelvis radiography.

METHODS

Surface topography data were collected using the formetic 4D dynamic modelling (Diers) system. 61 healthy participants were recruited; each participant performed eight different standing positions. Four positions were performed with the feet shoulder width apart and parallel, and four positions were performed with the feet shoulder width apart and internally rotated. For the upper extremity, each of the (two sets of) four positions were performed with different arm positions (arms by the sides, arms crossed over the chest, arms 30° flexed and touching the medial end of the clavicle, arms 30° flexed with the hands holding a support). Three sets of surface topography were collected in the eight positions (n = 24). The variability was assessed by calculating standard error of the measurement (SEm) and the coefficient of variation (CV). Reliability was assessed using intra-class correlation coefficients (ICC ± 95% CI).

RESULTS

No significant differences in the SEm were found between the three paired measurements for all standing positions (P > 0.05). ICC values demonstrated excellent reliability for all measurements across the eight standing positions (range 0.879-1.00 [95% CI 0.813-1.00]).

CONCLUSION

Evaluating eight standing positions radiographically would be unethical as it would involve repeat radiation exposures. Using the formetic 4D dynamic modelling (Diers) system, provides an alternative and has shown that there was only a minimal, non-statistically significant, differences between the eight different standing positions.

IMPLICATION FOR PRACTICE

Different standing positions were proposed for erect pelvis radiography.

ADOLESCENT IDIOPATHIC SCOLIOSIS AND SIMILAR CONDITIONS: NEW TOOL TO MEASURE THE CORONAL PLANE

ABSTRACT Objective: To create a method to measure the overall coronal plane of the spine, called the sacral clavicular angle (SCA). Methods: A line is drawn at the base of the sacrum; a second central line is drawn perpendicular to the first one in the proximal extension of the spine. A third line is drawn passing through the intersections of the superior points of the clavicles with the two second ribs, forming two angles, the greater of which is measured. Therefore, the degrees exceeding 90° are the SCA values. This tool was tested retrospectively in a study of 46 patients with idiopathic scoliosis who underwent short, apical, single or multiple fixations. Third generation instrumentation was used and the SCA was evaluated in the pre- and postoperative periods, which were compared with another group of 46 patients treated with the traditional technique. Results: Patients submitted to the traditional fixation method presented a median SCA of 3° in the preoperative period, and in the postoperative period, the SCA remained in 3°. Therefore, there was a 0% reduction. Patients submitted to short, apical, single or multiple fixation method presented a median preoperative SCA of 6°, and a postoperative median SCA of 1°, a reduction of approximately 83%. Conclusions: The group treated with short, apical, single or multiple instrumentation presented a reduction in the SCA of approximately 83% in the postoperative period compared to the preoperative period. The difference between preoperative and postoperative values was considered statistically significant. Level of Evidence II; Retrospective study.

3D Markerless asymmetry analysis in the management of adolescent idiopathic scoliosis

BACKGROUND

Three dimensional (3D) markerless asymmetry analysis was developed to assess and monitor the scoliotic curve. While the developed surface topography (ST) indices demonstrated a strong correlation with the Cobb angle and its change over time, it was reported that the method requires an expert for monitoring the procedure to prevent misclassification for some patients. Therefore, this study aimed at improving the user-independence level of the previously developed 3D markerless asymmetry analysis implementing a new asymmetry threshold without compromising its accuracy in identifying the progressive scoliotic curves.

METHODS

A retrospective study was conducted on 128 patients with Adolescent Idiopathic Scoliosis (AIS), with baseline and follow-up radiograph and surface topography assessments. The suggested "cut point" which was used to separate the deformed surfaces of the torso from the undeformed regions, automatically generated deviation patches corresponding to scoliotic curves for all analyzed surface topography scans.

RESULTS

By changing the "cut point" in the asymmetry analysis for monitoring scoliotic curves progression, the sensitivity for identifying curve progression was increased from 68 to 75%, while the specificity was decreased from 74 to 59%, compared with the original method with different "cut point".

CONCLUSIONS

These results lead to a more conservative approach in monitoring of scoliotic curves in clinical applications; smaller number of radiographs would be saved, however the risk of having non-measured curves with progression would be decreased.

A computerized method for evaluating scoliotic deformities using elliptical pattern recognition in X-ray spine images

BACKGROUND AND OBJECTIVE

Several studies have evaluated the reproducibility of the Cobb angle for measuring the degree of scoliotic deformities from X-ray spine images, and proposed different geometric models for describing the spinal curvature. The ellipse was shown to be an adequate geometric form, but was not yet applied for the identification and quantification of scoliotic curvatures. The purpose of this study is therefore to propose and validate a novel computerized methodology for the detection of elliptical patterns from X-ray images to evaluate the extent of the underlying scoliotic deformity.

METHODS

For anteroposterior each X-ray spine image, the spine curve is first reconstructed from vertebral centroids. The ellipse that best fits to the obtained spine curve is the found within a least square and genetic algorithm optimization framework. The geometric parameters of the resulting best fit ellipse are finally used to define an index that quantifies the spinal curvature.

RESULTS

The proposed methodology was validated on three synthetic images and then successfully applied to 20 clinical anteroposterior X-ray spine images of patients with a different degree of scoliotic deformity, with the resulting maximal relative error of 3% for the synthetic images and an overall error of 0.5 ± 0.4 mm (mean ± standard deviation) for the clinical cases.

CONCLUSIONS

The results indicate that the proposed computerized methodology is able to reliably reproduce scoliotic curvatures using the geometric parameters of the underlying ellipses. In comparison to conventional approaches, the proposed methodology potentially produces less errors, requires a relatively low observer interaction, takes into account all vertebrae within the observed scoliotic deformity, and allows for both qualitative and quantitative evaluations that may complement the diagnosis, study and treatment of scoliosis.

What is the optimal cutoff value of the axis-line-angle technique for evaluating trunk imbalance in coronal plane?

BACKGROUND CONTEXT

Accurately evaluating the extent of trunk imbalance in the coronal plane is significant for patients before and after treatment. We preliminarily practiced a new method, axis-line-angle technique (ALAT), for evaluating coronal trunk imbalance with excellent intra-observer and interobserver reliability. Radiologists and surgeons were encouraged to use this method in clinical practice. However, the optimal cutoff value of the ALAT for determination of the extent of coronal trunk imbalance has not been calculated up to now.

PURPOSE

The purpose of this study was to identify the cutoff value of the ALAT that best predicts a positive measurement point to assess coronal balance or imbalance.

STUDY DESIGN/SETTING

A retrospective study at a university affiliated hospital was carried out.

PATIENT SAMPLE

A total of 130 patients with C7-central sacral vertical line (CSVL) >0 mm and aged 10-18 years were recruited in this study from September 2013 to December 2014.

OUTCOME MEASURES

Data were analyzed to determine the optimal cutoff value of the ALAT measurement.

METHODS

The C7-CSVL and ALAT measurements were conducted respectively twice on plain film within a 2-week interval by two radiologists. The optimal cutoff value of the ALAT was analyzed via receiver operating characteristic (ROC) curve. Comparison variables were performed with chi-square test between the C7-CSVL and ALAT measurements for evaluating trunk imbalance. Kappa agreement coefficient method was used to test the intra-observer and interobserver agreement of C7-CSVL and ALAT.

RESULTS

The ROC curve area for the ALAT was 0.82 (95% confidence interval: 0.753-0.894, p<.001). The maximum Youden index was 0.51, and the corresponding cutoff point was 2.59°. No statistical difference was found between the C7-CSVL and ALAT measurements for evaluating trunk imbalance (p>.05). Intra-observer agreement values for the C7-CSVL measurements by observers 1 and 2 were 0.79 and 0.91 (p<.001), respectively, whereas intra-observer agreement values for the ALAT measurements were both 0.89 by observers 1 and 2 (p<.001). The interobserver agreement values for the first and second measurements with the C7-CSVL were 0.78 and 0.85 (p<.001), respectively, whereas the interobserver agreement values for the first and second measurements with the ALAT were 0.91 and 0.88 (p<.001), respectively.

CONCLUSIONS

The newly developed ALAT provided an acceptable optimal cutoff value for evaluating trunk imbalance in the coronal plane with a high level of intra-observer and interobserver agreement, which suggests that the ALAT is suitable for clinical use.

Validity and Reliability of Spine Rasterstereography in Patients With Adolescent Idiopathic Scoliosis

STUDY DESIGN

Test-retest study.

OBJECTIVE

This study aimed to evaluate the validity and reliability of rasterstereography in patients with adolescent idiopathic scoliosis (AIS) with a major curve Cobb angle (CA) between 10° and 40° for frontal, sagittal, and transverse parameters.

SUMMARY OF BACKGROUND DATA

Previous studies evaluating the validity and reliability of rasterstereography concluded that this technique had good accuracy compared with radiographs and a high intra- and interday reliability in healthy volunteers. To the best of our knowledge, the validity and reliability have not been assessed in AIS patients.

MATERIALS

Thirty-five adolescents with AIS (male = 13) aged 13.1 ± 2.0 years were included. To evaluate the validity of the scoliosis angle (SA) provided by rasterstereography, a comparison (t test, Pearson correlation) was performed with the CA obtained using 2D EOS® radiography (XR). Three rasterstereographic repeated measurements were independently performed by two operators on the same day (interrater reliability) and again by the first operator 1 week later (intrarater reliability). The variables of interest were the SA, lumbar lordosis, and thoracic kyphosis angle, trunk length, pelvic obliquity, and maximum, root mean square and amplitude of vertebral rotations. The data analyses used intraclass correlation coefficients (ICCs).

RESULTS

The CA and SA were strongly correlated (R = 0.70) and were nonsignificantly different (P = 0.60). The intrarater reliability (same day: ICC [1, 1], n = 35; 1 week later: ICC [1, 3], n = 28) and interrater reliability (ICC [3, 3], n = 16) were globally excellent (ICC > 0.75) except for the assessment of pelvic obliquity.

CONCLUSION

This study showed that the rasterstereographic system allows for the evaluation of AIS patients with a good validity compared with XR with an overall excellent intra- and interrater reliability. Based on these results, this automatic, fast, and noninvasive system can be used for monitoring the evolution of AIS in growing patients instead of repetitive radiographs, thereby reducing radiation exposure and decreasing costs.

LEVEL OF EVIDENCE

4.

COMPARISON OF COBB ANGLE MEASUREMENT IN SCOLIOSIS BY RESIDENTS AND SPINE EXPERTS

ABSTRACT Objective: The adolescent idiopathic scoliosis (AIS) is a spine deformity that occurs in both the coronal plane and the sagittal plane of patients between 10 and 17 years. The Cobb method is the most widely used to determine the angular value of scoliosis and it is defined as the "gold standard". The goal is to verify the reproducibility of the measured angles between orthopedic residents and spinal pathologies specialists, comparing the variability of the angles measured by professionals with greater and lesser experience. Method: A total of 10 radiographs of patients diagnosed with AIS were assessed. Radiographs were handed over to 7 orthopedists specialized in spine and 14 orthopedic residents. The measurement of the angles for each of the examiners was described using means and standard deviations and intraclass correlations were calculated, as well as the measure of repeatability, and Bland-Altman plots were designed with the results of the measurements of each group of examiners, according to experience, to assess the agreement/reproducibility of Cobb angle measurements. Results: Each examiner obtained a resulting average of 10 cases summation. In order to assess trends in variability of the measurements of the angles of each group graphs were plotted based on the arithmetic mean of each of the 10 cases by the total number of participants in the group versus the standard deviation in each case. Conclusion: There was a poor correlation (ICC=0.4) in the measurement of Cobb in both groups, demonstrating difficulties in the method, which cannot be overcome by the expertise.

Multicenter Comparison of 3D Spinal Measurements Using Surface Topography With Those From Conventional Radiography

INTRODUCTION

In pediatric spinal deformity the gold standard for curve surveillance remains standing full-column radiographs, but repeated exposure to ionizing radiation motivates us to look for nonradiographic solutions. This study tests a modern system of surface topography (ST) to determine whether it is reliable and reproducible.

METHODS

Patients from 6 pediatric spinal deformity clinics were recruited for enrollment. Inclusion criteria were age 8-18; diagnosis of scoliosis measuring ≥10 and <50 degrees or increased kyphosis of ≥45 degrees. Standing radiographs and ST scans (DIERS Formetric, Diers Medical Systems, Chicago, IL) were obtained on all patients and then measured and compared. A single investigator using a validated electronic measurement tool performed all radiographic measurements. Analysis of reproducibility and comparison of ST and radiographs were done.

RESULTS

A total of 193 patients were enrolled (148 F [77%]). The mean age was 13.25 years (range 8-18). The scoliosis magnitude was as follows: thoracic average 22.7 ± 10 degrees; lumbar average 19.6 ± 9 degrees. The kyphosis magnitude was 54.0 ± 11 degrees. The reproducibility for each ST parameter for 3 repeated scans was strong (interclass correlation = 0.855-0.944). Comparison to radiographic measurements was strong in the thoracic (r = 0.7) and moderate in the lumbar curve (r = 0.5). There was an average difference of 5.8 degrees in the thoracic spine and 8.8 degrees in the lumbar spine between ST Cobb angle estimates and radiographs. Thoracic kyphosis also had a strong correlation (r = 0.8) with radiographs.

CONCLUSIONS

Although the results are intended to measure similar aspects of deformity as the traditional Cobb angle, the measurement is not intended to be an exact estimation. The utility of ST is in the reproducible quantification of deformity after the initial radiograph has been taken. This has the potential to make longitudinal assessment of change in deformity without serial radiographs.

Reliability of a new method for measuring coronal trunk imbalance, the axis-line-angle technique

BACKGROUND CONTEXT

Accurate determination of the extent of trunk imbalance in the coronal plane plays a key role in an evaluation of patients with trunk imbalance, such as patients with adolescent idiopathic scoliosis. An established, widely used practice in evaluating trunk imbalance is to drop a plumb line from the C7 vertebra to a key reference axis, the central sacral vertical line (CSVL) in full-spine standing anterioposterior radiographs, and measuring the distance between them, the C7-CSVL. However, measuring the CSVL is subject to intraobserver differences, is error-prone, and is of poor reliability. Therefore, the development of a different way to measure trunk imbalance is needed.

PURPOSE

This study aimed to describe a new method to measure coronal trunk imbalance, the axis-line-angle technique (ALAT), which measures the angle at the intersection between the C7 plumb line and an axis line drawn from the vertebral centroid of the C7 to the middle of the superior border of the symphysis pubis, and to compare the reliability of the ALAT with that of the C7-CSVL.

STUDY DESIGN/SETTING

A prospective study at a university hospital was used.

PATIENT SAMPLE

The patient sample consisted of sixty-nine consecutively enrolled men and women patients, aged 10-18 years, who had trunk imbalance defined as C7-CSVL longer than 20 mm on computed full-spine standing anterioposterior radiographs.

OUTCOME MEASURES

Data were analyzed to determine the correlation between C7-CSVL and ALAT measurements and to determine intraobserver and interobserver reliabilities.

METHODS

Using a picture archiving and communication system, three radiologists independently evaluated trunk imbalance on the 69 computed radiographs by measuring the C7-CSVL and by measuring the angle determined by the ALAT. Data were analyzed to determine the correlations between the two measures of trunk imbalance, and to determine intraobserver and interobserver reliabilities of each of them.

RESULTS

Overall results from the measurements by the C7-CSVL and the ALAT were significantly moderately correlated. Intraobserver assessments by measuring the C7-CSVL and by doing the ALAT failed to find any significant differences between the findings from the first and second assessments by the same radiologist. Interobserver assessments significantly differed between radiologists 1 and 2 for the first assessment measuring the C7-CSVL, and between radiologists 2 and 3 for the second assessment measuring the C7-CSVL. Interobserver assessments by doing the ALAT failed to find any significant differences among the three radiologists for either of the two assessments.

CONCLUSIONS

Our results indicated that using the ALAT, which is simple and convenient, is of great value in measuring trunk imbalance. For measuring trunk imbalance, the ALAT has essential advantages compared with measuring the C7-CSVL. We encourage spine surgeons to consider using the ALAT in evaluating trunk imbalance.

Rasterstereographic measurement of scoliotic deformity

BACKGROUND

Back surface topography has gained acceptance in recent decades. At the same time, the motivation to use this technique has increased. From the view of the patient, the cosmetic aspect has played and still plays a major role as it provides a comprehensive documentation of cosmetic impairment. From the view of the medical practitioner, the aspect of reducing X-ray exposures in diagnosis and follow-up has been dominant and still prevails. Meanwhile, new aspects have emerged: due to the consequent three-dimensional view of the scoliotic condition, treatment success can be visualized convincingly. Clinical diagnosis is supported by information otherwise not supplied by X-rays, such as when functional examinations and diagnostic tests are recorded.

METHODS

Like rasterstereography, most techniques of actual back surface measurement refer to photogrammetry and the triangulation method. However, with respect to the particular clinical application, a wide spectrum of implementations exists. Applications in a clinic require high accuracy of measurement in a short time and comprehensive analysis providing data to be used to supplement and compare with radiographic data. This is exemplified by rasterstereography; the procedures of surface analysis and localization of landmarks using curvatures and the reconstruction of the spinal midline will be described.

ORTHOPAEDIC RELEVANCE

Based on rasterstereographic analysis, different geometrical measures that characterize the back surface are given and underlying skeletal structures described. Furthermore, in analogy to radiological projection, a 3-D reconstruction of the spinal midline is visualized by a frontal and lateral projection, allowing comparison with pertinent X-rays.

CONCLUSIONS

Surface topography and, in particular, rasterstereography provide reliable and consistent results that may be used to reduce X-ray exposure. Unfortunately, the correlation of shape parameters with the radiological Cobb angle is poor. However, the wealth of additional applications substantially enhances the spectrum of clinical value.

SOSORT 2012 consensus paper: reducing x-ray exposure in pediatric patients with scoliosis

This 2012 Consensus paper reviews the literature on side effects of x-ray exposure in the pediatric population as it relates to scoliosis evaluation and treatment. Alternative methods of spinal assessment and imaging are reviewed, and strategies for reducing the number of radiographs are developed. Using the Delphi technique, SOSORT members developed consensus statements that describe how often radiographs should be taken in each of the pediatric and adolescent sub-populations.

Reliability and reproducibility analysis of the Cobb angle and assessing sagittal plane by computer-assisted and manual measurement tools

Background

Although many studies on reliability and reproducibility of measurement have been performed on coronal Cobb angle, few results about reliability and reproducibility are reported on sagittal alignment measurement including the pelvis. We usually use SurgimapSpine software to measure the Cobb angle in our studies; however, there are no reports till date on its reliability and reproducible measurements.

Methods

Sixty-eight standard standing posteroanterior whole-spine radiographs were reviewed. Three examiners carried out the measurements independently under the settings of manual measurement on X-ray radiographies and SurgimapSpine software on the computer. Parameters measured included pelvic incidence, sacral slope, pelvic tilt, Lumbar lordosis (LL), thoracic kyphosis, and coronal Cobb angle. SPSS 16.0 software was used for statistical analyses. The means, standard deviations, intraclass and interclass correlation coefficient (ICC), and 95% confidence intervals (CI) were calculated.

Results

There was no notable difference between the two tools (P = 0.21) for the coronal Cobb angle. In the sagittal plane parameters, the ICC of intraobserver reliability for the manual measures varied from 0.65 (T2–T5 angle) to 0.95 (LL angle). Further, for SurgimapSpine tool, the ICC ranged from 0.75 to 0.98. No significant difference in intraobserver reliability was found between the two measurements (P > 0.05). As for the interobserver reliability, measurements with SurgimapSpine tool had better ICC (0.71 to 0.98 vs 0.59 to 0.96) and Pearson’s coefficient (0.76 to 0.99 vs 0.60 to 0.97). The reliability of SurgimapSpine measures was significantly higher in all parameters except for the coronal Cobb angle where the difference was not significant (P > 0.05).

Conclusion

Although the differences between the two methods are very small, the results of this study indicate that the SurgimapSpine measurement is an equivalent measuring tool to the traditional manual in coronal Cobb angle, but is advantageous in spino-pelvic measurement in T2-T5, PT, PI, SS, and LL.

A correlational study of scoliosis and trunk balance in adult patients with mandibular deviation

Previous studies have confirmed that patients with mandibular deviation often have abnormal morphology of their cervical vertebrae. However, the relationship between mandibular deviation, scoliosis, and trunk balance has not been studied. Currently, mandibular deviation is usually treated as a single pathology, which leads to poor clinical efficiency. We investigated the relationship of spine coronal morphology and trunk balance in adult patients with mandibular deviation, and compared the finding to those in healthy volunteers. 35 adult patients with skeletal mandibular deviation and 10 healthy volunteers underwent anterior X-ray films of the head and posteroanterior X-ray films of the spine. Landmarks and lines were drawn and measured on these films. The axis distance method was used to measure the degree of scoliosis and the balance angle method was used to measure trunk balance. The relationship of mandibular deviation, spine coronal morphology and trunk balance was evaluated with the Pearson correlation method. The spine coronal morphology of patients with mandibular deviation demonstrated an "S" type curve, while a straight line parallel with the gravity line was found in the control group (significant difference, p<0.01). The trunk balance of patients with mandibular deviation was disturbed (imbalance angle >1°), while the control group had a normal trunk balance (imbalance angle <1°). There was a significant difference between the two groups (p<0.01). The degree of scoliosis and shoulder imbalance correlated with the degree of mandibular deviation, and presented a linear trend. The direction of mandibular deviation was the same as that of the lateral bending of thoracolumbar vertebrae, which was opposite to the direction of lateral bending of cervical vertebrae. Our study shows the degree of mandibular deviation has a high correlation with the degree of scoliosis and trunk imbalance, all the three deformities should be clinically evaluated in the management of mandibular deviation.

A comparative analysis of 4 curvature measurement methods in early-onset scoliosis

STUDY DESIGN

Observational study with 3 examiners.

OBJECTIVE

The aim of this study was to enhance the reproducibility and reliability of coronal curvature measurements in early-onset scoliosis.

SUMMARY OF BACKGROUND DATA

Previous reports show high variability of the Cobb method, especially on the measurement of the immature spine.

METHODS

A total of 115 whole-spine posteroanterior radiographs were collected to compare the reliability of the Cobb, lateral tangent, pedicle, and centroid methods in early-onset scoliosis. Radiographs were measured twice by each of the 3 examiners using the 4 measurement methods. Statistical analysis was performed to determine the inter- and intraobserver reliability.

RESULTS

In this study, total inter- and intraobserver inter- and intraclass correlation coefficients (ICCs) in 115 radiographs were excellent in all methods (ICCs >0.961). However, mean absolute differences (MADs) in the lateral tangent method were less than 3.78°, which was higher than other methods (MADs <2.95°). In analysis of different severity groups (<15°, 15°-30°, and >30°), total inter- and intraobserver ICCs gradually increased with increasing the severity of the deformity, whereas MADs of each severity group were similar despite their increased measurement scale. Particularly, interobserver ICCs and MADs of lateral tangent method were more than 0.474 and less than 3.76° with poor reliability, which showed high variability in the less deformed spine group (<15°). However, intraobserver ICCs and MADs of pedicle method were more than 0.853 and less than 2.61°, interobserver ICCs and MADs were more than 0.729 and less than 2.86° with excellent reliability, which showed constantly high reliability regardless of coronal curvature severity.

CONCLUSION

In this study, the pedicle method showed constantly higher ICCs and lower MAD values in the early-onset scoliosis regardless of severity. However, the other 3 methods showed lower ICCs and higher MAD values, which showed lowest reliability in the lateral tangent method. For improved treatment of early-onset scoliosis, we recommend the pedicle method for measuring curvature regardless of severity.

Comparison of radiographic and surface topography measurements in adolescents with idiopathic scoliosis

Purpose:

In patients with adolescent idiopathic scoliosis (AIS), radiographic surveillance is the gold standard of assessing spinal deformity, but has negative long-term effects. The Formetric 4D surface topography system was compared to standard radiography as a safer option for evaluating patients with AIS.

Methods:

Fourteen volunteers with typical AIS patient stature had 30 repeated Formetric 4D measurements taken, and reproducibility was assessed. Sixty-four patients with AIS were then enrolled during routine clinic visits. Evaluation included standard radiographs and surface topography measurements. A comparison analysis was performed.

Results:

When assessing same-day repeated scans, a standard deviation of +/- 3.4 degrees for scoliosis curve measurements was determined, and the Reliability Coefficient (Cronbach) was very high (0.996). Cobb angles measured with the Formetric 4D differed from radiographic measurements by an average of 9.42 (lumbar) and 6.98 (thoracic) degrees, while the correlation between the two measurements was strong (95% confidence interval [CI]), 0.758 (lumbar) and 0.872 (thoracic) respectively.

Conclusions:

The Formetric 4D is comparable to radiography in terms of its test-retest reproducibility. Although this device does not predict curve magnitude exactly, the predictions correlate strongly with the Cobb angles determined from radiographs. It can be reliably used in the surveillance of patients with AIS.

A comparative study of axis-line-distance technique and Cobb method on assessing the curative effect on scoliosis

PURPOSE

To compare the axis-line-distance technique (ALDT) and Cobb method for therapeutic evaluation of scoliosis.

METHODS

Fifty-seven patients with scoliosis were treated in our hospital, 47 underwent conservative bracing therapy and 10 underwent surgery. Based on 171 full-spine X-ray images obtained from these 57 cases before treatment, during conservative treatment or surgery, and at final follow-up after removing the brace or after surgery, two radiologists independently measured and calculated the correction rate during treatment and at final follow-up and the rate of correction loss after treatment with the ALDT and Cobb methods. Paired t-test and correlation analysis were performed.

RESULTS

Based on the ALDT, the lateral deviations of the apical vertebrae before treatment, during treatment, and at final follow-up were 31 ± 14 mm, 16 ± 8 mm, and 20 ± 8 mm, respectively; the correction rates during treatment and at final follow-up were 48.7 ± 21.2% and 37.6 ± 14.2%, respectively, and the rate of correction loss after treatment was 11.3 ± 6.5%. The Cobb angles of scoliosis before treatment, during treatment, and at final follow-up were 34 ± 14°, 19 ± 7°, and 22 ± 6°, respectively; the correction rates during treatment and at final follow-up were 44.4 ± 17.3% and 33.9 ± 14.4%, respectively, and the rate of correction loss after treatment was 11.4 ± 4.3%. Calculation of the correction rate during treatment differed significantly between the two radiologists when using the Cobb method (P < 0.05); their calculations of the correction rate and rate of correction loss were not different (P > 0.05). The measurement data of the two radiologists using the Cobb method showed a weak to moderate correlation (r = 0.49, 0.57, and 0.51, respectively). When using the ALDT, there were no significant differences between the radiologists in their measurements of the correction rate during and after treatment (P > 0.05) or in the rate of correction loss. The measurement data of the two radiologists using the ALDT showed a good to excellent correlation (r = 0.92, 0.93, and 0.90, respectively).

CONCLUSION

The ALDT is better than the Cobb method for therapeutic evaluation of scoliosis during treatment and at follow-up visits.

Centroid method: reliable method to determine the coronal curvature of scoliosis: a case control study comparing with the Cobb method

STUDY DESIGN

Observational study with three examiners.

OBJECTIVE

To compare the reliability of the Cobb and centroid methods.

SUMMARY OF BACKGROUND DATA

The Cobb method is considered to be the gold standard in scoliosis measurement despite its low reliability. In adolescent idiopathic scoliosis (AIS) patients, the centroid method can be a good method for measuring scoliosis.

METHODS

Sixty whole spine postero-anterior radiographs were collected to compare the reliability of the Cobb and centroid methods in AIS patients. Sixty radiographs were measured twice by each of the three examiners using the two measurement methods. The data were analyzed statistically to determine the inter- and intraobserver reliability.

RESULT

In comparisons of inter- and intraobserver reliability of all 60 radiographs, the inter- and intraclass coefficients (ICCs) were higher in the centroid (>0.969) than in the Cobb method (>0.832), although both were in the excellent range. The mean absolute difference (MAD) values were higher in the Cobb method (<7.15° vs. <3.75°), and >5° in five comparisons. Regarding measures of mismatched radiograms, the inter- and intraobserver MAD values were higher in the Cobb method (<9.81° vs. <3.82°), and >5° in six comparisons. And, the ICCs were higher in the centroid method (>0.972) than the Cobb method (>0.758). In immature radiograms, the ICCs were higher in the centroid (>0.973) than in the Cobb method (>0.764), even though it was in the excellent range. And, the inter- and intraobserver MAD values were higher in the Cobb method (<8.49° vs. <3.99°), and >5° in seven comparisons.

CONCLUSION

The centroid method is more reliable for measuring scoliosis in AIS than the Cobb method, and it can substitute the Cobb method, which showed high variability.

Mensuração da curva escoliótica pela técnica de cobb intraobservadores e interobservadores e sua importância clínica

OBJETIVO: Analisar a mensuração manual do ângulo de Cobb entre profissionais com diferentes experiências da área de Ortopedia e Traumatologia e Cirurgia da Coluna Vertebral, para observar se existem diferenças na avaliação das radiografias de pacientes portadores de escoliose idiopática intra e interobservadores, a ponto de influenciar no tratamento e seguimento desses pacientes. MÉTODOS: Foram utilizadas para este estudo 22 radiografias simples da coluna toracolombar, póstero-anterior, de pacientes portadores de escoliose idiopática, em acompanhamento regular no ambulatório do Grupo da Coluna do Hospital São Paulo. Os exames foram avaliados por quatro diferentes categorias de profissionais ortopedistas e cirurgiões da coluna vertebral e realizada a mensuração das curvas escolióticas através do método de Cobb. As vértebras terminais das curvas não foram previamente marcadas. Somente foram mensuradas as curvas principais (consideradas as de maior valor angular) de cada radiografia. A reprodutibilidade das mensurações feitas pelos diferentes Observadores (inter-observadores) e entre as duas mensurações de cada Observador (intraobservador) foi analisada pelo Coeficiente de Correlação Intraclasse (CCI). RESULTADOS: Foram observadas, quanto às medidas dos ângulos, concordâncias excelentes entre as avaliações intraobservadores, e observadas concordâncias excelentes entre as avaliações interobservadores, uma vez que o CCI em todas as situações manteve-se maior que 0,75, o que representa excelente reprodutibilidade. CONCLUSÃO: Concluímos que houve concordância excelente (CCI > 0,75) na avaliação dos ângulos nas mensurações das curvas escolióticas intra e interobservadores. Ao mesmo tempo, as mensurações apresentaram variação de até 13,58º intraobservadores, e de até 12,72º interobservadores.