Reliability of a functional classification system in the monitoring of patients with idiopathic scoliosis

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°).

Characterising the Mould Rectification Process for Designing Scoliosis Braces: Towards Automated Digital Design of 3D-Printed Braces

The plaster-casting method to create a scoliosis brace consists of mould generation and rectification to obtain the desired orthosis geometry. Alternative methods entail the use of 3D scanning and CAD/CAM. However, both manual and digital design entirely rely on the orthotist expertise. Characterisation of the rectification process is needed to ensure that digital designs are as efficient as plaster-cast designs. Three-dimensional scans of five patients, pre-, and post-rectification plaster moulds were obtained using a Structure Mark II scanner. Anatomical landmark positions, transverse section centroids, and 3D surface deviation analyses were performed to characterise the rectification process. The rectification process was characterised using two parameters. First, trends in the external contours of the rectified moulds were found, resulting in lateral tilt angles of 81 ± 3.8° and 83.3 ± 2.6° on the convex and concave side, respectively. Second, a rectification ratio at the iliac crest (0.23 ± 0.04 and 0.11 ± 0.02 on the convex and concave side, respectively) was devised, based on the pelvis width to estimate the volume to be removed. This study demonstrates that steps of the manual rectification process can be characterised. Results from this study can be fed into software to perform automatic digital rectification.

Anatomical reference marks, evaluation parameters and reproducibility of surface topography for evaluating the adolescent idiopathic scoliosis: a systematic review with meta-analysis

BACKGROUND

Surface topography is a radiation-free examination that provides relevant information for the evaluation of patients with Adolescent Idiopathic Scoliosis (AIS). However, its usage is not standardized, which restricts the applicability of this instrument.

RESEARCH QUESTIONS

(a) To identify the anatomical reference markers used on surface topography; (b) to identify the parameters used on surface topography; and (c) to pool correlation and reproducibility results.

METHODS

Systematic searches were conducted following MOOSE (Meta-analysis of Observational Studies in Epidemiology) guidelines. The methodological quality was assessed according to Brink & Louw appraisal tool.

RESULTS

Twenty-three studies were included for the qualitative synthesis. The most commonly used anatomical reference markers were: the prominent vertebra (C7 or T1), the posterior superior iliac spines (PSISs) and the sacrum (S1). The parameters for the evaluation of the AIS by surface topography are: spinal inclination angle (analogous to Cobb), gibbosity, thoracic kyphosis angle, lumbar lordosis angle, pelvic obliquity, spine length, apex of the curve, C7-S1 distance (frontal plane), and C7-S1 displacement (sagittal plane). Data from eleven studies were metanalyzed and evidenced the correlation of the surface topography with X-ray exams and the reproducibility of the surface topography in the sagittal and frontal planes.

SIGNIFICANCE

The findings of this study recommend the use of a protocol for the application of the equipment. The analyzed studies predict the use of only four markers for anatomical reference. The evaluation of the AIS can be carried out observing nine parameters. Surface topography correlates with radiography when the spinal inclination angle (Cobb angle), thoracic kyphosis angle and lumbar lordosis angle are compared. Also, surface topography presents inter and intra-rater reproducibility in the sagittal plane and intra-rater reproducibility in the frontal plane.

The Validity of Rasterstereography: A Systematic Review

To investigate and monitor the progression of scoliosis and other spinal deformities in patients following idiopathic scoliosis (IS), non-invasive and radiation-free techniques are recommended because of the need for repeated radiographs. In a clinical setting, spine parameters can be quickly, cheaply and easily assessed using rasterstereography (RS). To assess the validity of the radiation-free technique RS based on surface topography compared with radiographs. MEDLINE, the Cochrane Library and EMBASE were systematically searched for studies which investigate the validity of rasterstereography compared with x-ray measurements. Studies published between January 1, 1990 and July 31, 2013 in English, German and French were included. Studies dealing with magnetic resonance imaging were excluded. Twelve studies with 570 patients were included; these articles were published between 1990 and 2013. The majority of studies investigated patients with IS, but other spinal pathologies included were thoracic hyperkyphosis and Scheuermann’s disease. With regard to the quality assessment criteria for the included studies, three out of twelve studies were evaluated using a twelve point scale and two used a scale with eleven points. We conclude that RS facilitates clinical practice by analysing the spinal column. It is completely radiation-free and could help to monitor scoliosis progression.

Monitoring for idiopathic scoliosis curve progression using surface topography asymmetry analysis of the torso in adolescents

BACKGROUND CONTEXT

At first visit and each clinical follow-up session, patients with adolescent idiopathic scoliosis (AIS) undergo radiographic examination, from which the Cobb angle is measured. The cumulative exposure to X-ray radiation justifies efforts in developing noninvasive methods for scoliosis monitoring.

PURPOSE

To determine the capability of the three-dimensional markerless surface topography (ST) asymmetry analysis to detect ≥5° progression in the spinal curvature in patients with AIS over 1-year follow-up interval.

STUDY DESIGN/SETTING

Cross-sectional study in a specialized scoliosis clinic.

PATIENT SAMPLE

In this study, baseline and 1-year follow-up full torso ST scans of 100 patients with AIS were analyzed using three-dimensional markerless asymmetry analysis.

OUTCOME MEASURES

Patients with ΔCobb≥5° and ΔCobb<5° were categorized into progression and nonprogression groups, respectively.

METHODS

The ST scan of each full torso was analyzed to calculate the best plane of symmetry by minimizing the distances between the torso and its reflection about the plane of symmetry. Distance between the torso and its reflection was measured and displayed as deviation color maps. The difference of ST measurements between two successive acquisitions was used to determine if the scoliosis has progressed at least 5° or not. The classification tree technique was implemented using the local deformity of the torso in the thoracic-thoracolumbar (T-TL) and lumbar (L) regions to categorize curves into progression and nonprogression groups. The change in maximum deviation and root mean square of the deviations in the torso were the parameters effective in capturing the curve progression. Funding for this research is provided by the Scoliosis Research Society, and Women and Children's Health Research Institute.

RESULTS

The classification model detected 85.7% of the progression and 71.6% of the nonprogression cases. The resulting false-negative rate of 4% for T-TL curves, representing the proportion of undetected progressions, confirmed that the technique shows promise to monitor the progression of T-TL scoliosis curves. Although 100% L curves with progression were detected using the deviation color maps of the torsos, because of the small number of analyzed L curves, further research is needed before the efficiency of the method in capturing the L curves with progression is confirmed.

CONCLUSIONS

Using the developed classification tree for the patients analyzed in this study, 43% of nonprogression cases between two visits would not have to undergo an X-ray examination.

Comparison of parameters characterizing lumbar lordosis in radiograph and photogrammetric examination of adults

OBJECTIVE

The purpose of this study was to test validity of photogrammetry compared with radiography as a method of measuring the Cobb angle and the size of anterior-posterior spine curvatures in adults.

METHODS

The study included 50 volunteers, 23 men and 27 women whose mean age was 52.6 years. The average weight of the subjects was 81.3 kg, average body height was 172.0 cm, and the average body mass index was 27.4. Based on radiologic examination, the length and depth of lumbar lordosis were determined and the size of the Cobb angle of lumbar scoliosis. After the radiologic examination, a photogrammetric test was performed for each subject with the projection moire phenomenon.

RESULTS

The Pearson correlation found statistically significant associations concerning the length of lordosis (P < .001) and the Cobb angle (P < .001). Correlation of the depth of lordosis indicated a strong trend (P = .063).

CONCLUSIONS

This study found that the moire method of photogrammetric measurement produced similar findings to radiographic measurements in determining size of the Cobb angle and the length of lumbar lordosis.

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.

Development of a 3-Dimensional Back Contour Imaging System for Monitoring Scoliosis Progression in Children

STUDY DESIGN

Control study.

OBJECTIVES

To present a new surface topography system capable of taking 3-dimensional (3D) spine measurements, to establish baseline values for the measured parameters in a typically developing population, and to determine the intra-rater and inter-rater reproducibility of these parameters.

SUMMARY OF BACKGROUND DATA

Cumulative exposure to radiation from diagnostic radiographs increases patient risk for cancer development. There is a need for noninvasive and non-radiographic tools to accurately and reproducibly measure spine deformity and track scoliosis progression.

METHODS

We measured 10 typically developing subjects with the new Milwaukee Topography System, which is composed of 2 electromagnetic markers, an electronic processing unit, a handheld laser scanner, a software package, and a desktop computer. Two investigators separately scanned the same subjects multiple times, yielding a total of 4 scans per subject per investigator. We measured 17 3D back parameters in each scan. We performed a multivariate analysis of variances to test the hypothesis of no difference for all variables, measured intra-rater and inter-investigator reliability with intra-class correlation (ICC) coefficients, and calculated mean values.

RESULTS

There were highly reproducible ICC values between investigators for 6 parameters (ICC > 0.75), moderate ICC values for 8 parameters (0.75 > ICC > 0.4), and poor ICC values for 3 parameters (ICC < 0.4), all at p < .05. Intra-investigator ICCs were moderate to excellent for almost all parameters.

CONCLUSIONS

The Milwaukee Topography System can be used to monitor and measure 3D back contours in children. The 3D back parameters values measured in the typically developing population can be considered baseline values that can be compared with parameters measured in children with idiopathic scoliosis.

Reproducibility of newly developed spinal topography measurements for scoliosis

Objective:

In an effort to limit exposure to ionizing radiation and fully characterize three dimensional changes in the spine of patients with scoliosis reliable non-invasive methods of spinal back contour analysis (Milwaukee Topographic Scanner) (MTS) have been developed.

Study Design:

The current study compares spinal topography measurements among different subject positions and evaluates the reproducibility of the system for both inter-rater and intra-rater reliability.

Methods:

A dummy cast (plastic cast) of one patient with adolescent idiopathic scoliosis was created in order to test the reliability of the MTS. The dummy cast was positioned and rotated in 3D while scanned by two investigators using the MTS. A total of twelve parameters including Q-angle (an analog to X-ray’s Cobb angle) were extracted.

Results:

All measurements of intra-rater and inter-rater reliability were excellent (Intraclass Correlation Coefficients ranging from 0.89 to 0.99) with the exception of Pelvic Tilt (intra-rater ICC is 0.61) and lordosis angle (inter-rater ICC is 0.82). No significant variability among investigators was observed for all tested metrics. No significant variability due to position was observed for the majority of back contour measurements but there were significant changes in the T1-S1 angle, T1-S1 deviation, T1-NC angle, T1-NC deviation, and Back Height metric (p< 0.05).

Conclusions:

The MTS is a reliable method of raster stereography in the measurement of the back contour, which will help monitor the progression of children with idiopathic scoliosis and reduce the use of X-rays.

New method of scoliosis assessment: preliminary results using computerized photogrammetry

STUDY DESIGN

A new method for nonradiographic evaluation of scoliosis was independently compared with the Cobb radiographic method, for the quantification of scoliotic curvature.

OBJECTIVE

To develop a protocol for computerized photogrammetry, as a nonradiographic method, for the quantification of scoliosis, and to mathematically relate this proposed method with the Cobb radiographic method.

SUMMARY OF BACKGROUND DATA

Repeated exposure to radiation of children can be harmful to their health. Nevertheless, no nonradiographic method until now proposed has gained popularity as a routine method for evaluation, mainly due to a low correspondence to the Cobb radiographic method.

METHODS

Patients undergoing standing posteroanterior full-length spine radiographs, who were willing to participate in this study, were submitted to dorsal digital photography in the orthostatic position with special surface markers over the spinous process, specifically the vertebrae C7 to L5. The radiographic and photographic images were sent separately for independent analysis to two examiners, trained in quantification of scoliosis for the types of images received. The scoliosis curvature angles obtained through computerized photogrammetry (the new method) were compared to those obtained through the Cobb radiographic method.

RESULTS

Sixteen individuals were evaluated (14 female and 2 male). All presented idiopathic scoliosis, and were between 21.4 ± 6.1 years of age; 52.9 ± 5.8 kg in weight; 1.63 ± 0.05 m in height, with a body mass index of 19.8 ± 0.2. There was no statistically significant difference between the scoliosis angle measurements obtained in the comparative analysis of both methods, and a mathematical relationship was formulated between both methods.

CONCLUSION

The preliminary results presented demonstrate equivalence between the two methods. More studies are needed to firmly assess the potential of this new method as a coadjuvant tool in the routine following of scoliosis treatment.

Reproducibility of rasterstereography for kyphotic and lordotic angles, trunk length, and trunk inclination: a reliability study

STUDY DESIGN

Determination of reliability with 3 investigators using a collective of healthy volunteers.

OBJECTIVE

To determine the reliability of rasterstereography 3-dimensional back surface analysis and reconstruction of the spine in healthy test subjects.

SUMMARY OF BACKGROUND DATA

Rasterstereography has been in clinical use since 1989 for patients with scoliosis and other spinal deformities and it significantly reduces the need for otherwise indispensable radiographs. The validity of this device has previously been examined in other studies. This study was performed to evaluate the reliability of rasterstereography for clinical application in diagnostic and follow-up examinations.

METHODS

Fifty-one healthy volunteers were examined rasterstereographically by 3 investigators. Each investigator made a series of 3 measurements of each participant in which 8 spine parameters including kyphotic angle ICT-ITL (max.), kyphotic angle VP-ITL, kyphotic angle VP-T12, lordotic angle ITL-ILS (max.), lordotic angle ITL-DM, lordotic angle T12-DM, trunk length VP-DM and trunk inclination were measured. Cronbach alpha was calculated. The influence of high or low body mass index on the accuracy of the technique was evaluated as well.

RESULTS

Cronbach alpha for the intratester-reliability of the kyphotic angle ICT-ITL (max.) for the 3 investigators has values between 0.921 and 0.992. The intertester-reliability for the same parameter is 0.979 (95% CI). In this study group a meaningful association between body mass index and reliability of the device was not found.

CONCLUSION

The reliability revealed very good results, both for intratester and for intertester reliability. The technique is well suited for analysis of the back in standing position. The body mass index has no influence on the reproducibility.