Variability in Cobb angle measurements in children with congenital scoliosis

Conquering the Cobb Angle: A Deep Learning Algorithm for Automated, Hardware-Invariant Measurement of Cobb Angle on Radiographs in Patients with Scoliosis

Scoliosis is a disease estimated to affect more than 8% of adults in the United States. It is diagnosed with use of radiography by means of manual measurement of the angle between maximally tilted vertebrae on a radiograph (ie, the Cobb angle). However, these measurements are time-consuming, limiting their use in scoliosis surgical planning and postoperative monitoring. In this retrospective study, a pipeline (using the SpineTK architecture) was developed that was trained, validated, and tested on 1310 anterior-posterior images obtained with a low-dose stereoradiographic scanning system and radiographs obtained in patients with suspected scoliosis to automatically measure Cobb angles. The images were obtained at six centers (2005-2020). The algorithm measured Cobb angles on hold-out internal (n = 460) and external (n = 161) test sets with less than 2° error (intraclass correlation coefficient, 0.96) compared with ground truth measurements by two experienced radiologists. Measurements, produced in less than 0.5 second, did not differ significantly (P = .05 cutoff) from ground truth measurements, regardless of the presence or absence of surgical hardware (P = .80), age (P = .58), sex (P = .83), body mass index (P = .63), scoliosis severity (P = .44), or image type (low-dose stereoradiographic image vs radiograph; P = .51) in the patient. These findings suggest that the algorithm is highly robust across different clinical characteristics. Given its automated, rapid, and accurate measurements, this network may be used for monitoring scoliosis progression in patients. Keywords: Cobb Angle, Convolutional Neural Network, Deep Learning Algorithms, Pediatrics, Machine Learning Algorithms, Scoliosis, Spine Supplemental material is available for this article. © RSNA, 2023.

Hemivertebra Resection in Small Children. A Literature Review

STUDY DESIGN

Systematic review.

OBJECTIVE

To evaluate the lowest possible age to resect an HV in very young patients with a congenital deformity.

METHODS

We sought to retrieve all studies reporting age at HV excision in patients with congenital scoliosis. Studies written in English were included. No publication date restrictions were imposed. A search of the PubMed and LiLacs databases was conducted. Additionally, a hand search was performed to supplement the database search.

RESULTS

We found 140 articles. Twenty two studies were included into the final assessment. There was considerable heterogeneity in the included studies, both regarding age and the surgical techniques used. There was also a broad spectrum of recommendations regarding suggested age for treatment. The youngest patient undergoing resection and fusion was 3 months of life at the time of surgery.

CONCLUSION

How young a patient could and should be submitted to HV resection surgery is still a matter of debate in the literature. Prophylactic surgery might be a proper treatment for young children with congenital scoliosis before malformation becomes a deformity, adding no additional neurological, vascular, or anesthesia-related complications. The defect can be treated early while the deformity is treated late.

Reliability of Preoperative Supine Versus Bending Radiographs in Estimating the Structural Nature of Curves in EOS

BACKGROUND

The study sought to evaluate the utility of a single supine radiograph in determining curve flexibility in early-onset scoliosis (EOS) patients.

METHODS

EOS patients with upright (standing/seated), supine, and side-bending radiographs who underwent spinal deformity surgery were identified. Coronal parameters included: proximal thoracic (PT) curve, main thoracic (MT) curve, and thoracolumbar/lumbar (TL/L) curve. Each radiograph was measured twice by 2 different raters. Correlation coefficients were utilized to investigate associations between the different radiographs. Interrater Correlation Coefficient (ICC) assessed intrarater and interrater reliability.

RESULTS

Thirty-seven EOS patients were identified (age at diagnosis: 7.0±2.9 y, preoperative age: 13.0±2.9 y; 73% female; etiologies: 54% idiopathic, 30% syndromic, and 16% neuromuscular). Supine PT and MT curve measurements were highly associated with corresponding side-bending measurements (PT: r=0.75, P<0.001; MT: r=0.80, P<0.001), and TL/L curves were very highly associated (TL/L: r=0.92, P<0.001). The mean absolute differences between supine and side-bending measurements were PT: 11.3±7.8 degrees, MT: 14.8±8.3 degrees, and TL/L: 16.2±7.6 degrees, where the side-bending was on average smaller than the supine measurement. The intrarater reliabilities were excellent, with an ICC ranging from 0.93 to 0.96 for side-bending films and 0.94 to 0.97 for supine films. The interrater reliability was excellent with ICC value of 0.88 for side-bending films and 0.93 for supine films.

CONCLUSIONS

A single, preoperative supine radiograph was highly predictive of side-bending radiographs in patients with EOS. Supine curves measured an average of 15 degrees larger than bending curves in the MT and TL/L region. A single supine film may eliminate the need for effort-related, dual side-bending radiographs.

LEVEL OF EVIDENCE

Level II-retrospective study.

Automating Scoliosis Measurements in Radiographic Studies with Machine Learning: Comparing Artificial Intelligence and Clinical Reports

Scoliosis is a condition of abnormal lateral spinal curvature affecting an estimated 2 to 3% of the US population, or seven million people. The Cobb angle is the standard measurement of spinal curvature in scoliosis but is known to have high interobserver and intraobserver variability. Thus, the objective of this study was to build and validate a system for automatic quantitative evaluation of the Cobb angle and to compare AI generated and human reports in the clinical setting. After IRB was obtained, we retrospectively collected 2150 frontal view scoliosis radiographs at a tertiary referral center (January 1, 2019, to January 1, 2021, ≥ 16 years old, no hardware). The dataset was partitioned into 1505 train (70%), 215 validation (10%), and 430 test images (20%). All thoracic and lumbar vertebral bodies were segmented with bounding boxes, generating approximately 36,550 object annotations that were used to train a Faster R-CNN Resnet-101 object detection model. A controller algorithm was written to localize vertebral centroid coordinates and derive the Cobb properties (angle and endplate) of dominant and secondary curves. AI-derived Cobb angle measurements were compared to the clinical report measurements, and the Spearman rank-order demonstrated significant correlation (0.89, p < 0.001). Mean difference between AI and clinical report angle measurements was 7.34° (95% CI: 5.90-8.78°), which is similar to published literature (up to 10°). We demonstrate the feasibility of an AI system to automate measurement of level-by-level spinal angulation with performance comparable to radiologists.

The prognosis and recovery of major postoperative neurological deficits after corrective surgery for scoliosis : an analysis of 65 cases at a single institution

AIMS

The outcome following the development of neurological complications after corrective surgery for scoliosis varies from full recovery to a permanent deficit. This study aimed to assess the prognosis and recovery of major neurological deficits in these patients, and to determine the risk factors for non-recovery, at a minimum follow-up of two years.

METHODS

A major neurological deficit was identified in 65 of 8,870 patients who underwent corrective surgery for scoliosis, including eight with complete paraplegia and 57 with incomplete paraplegia. There were 23 male and 42 female patients. Their mean age was 25.0 years (SD 16.3). The aetiology of the scoliosis was idiopathic (n = 6), congenital (n = 23), neuromuscular (n = 11), neurofibromatosis type 1 (n = 6), and others (n = 19). Neurological function was determined by the American Spinal Injury Association (ASIA) impairment scale at a mean follow-up of 45.4 months (SD 17.2). the patients were divided into those with recovery and those with no recovery according to the ASIA scale during follow-up.

RESULTS

The incidence of major deficit was 0.73%. At six-month follow-up, 39 patients (60%) had complete recovery and ten (15.4%) had incomplete recovery; these percentages improved to 70.8% (46) and 16.9% (11) at follow-up of two years, respectively. Eight patients showed no recovery at the final follow-up. The cause of injury was mechanical in 39 patients and ischaemic in five. For 11 patients with misplaced implants and haematoma formation, nine had complete recovery. Fisher's exact test showed a significant difference in the aetiology of the scoliosis (p = 0.007) and preoperative deficit (p = 0.016) between the recovery and non-recovery groups. A preoperative deficit was found to be significantly associated with non-recovery (odds ratio 8.5 (95% confidence interval 1.676 to 43.109); p = 0.010) in a multivariate regression model.

CONCLUSION

For patients with scoliosis who develop a major neurological deficit after corrective surgery, recovery (complete and incomplete) can be expected in 87.7%. The first three to six months is the time window for recovery. In patients with misplaced implants and haematoma formation, the prognosis is satisfactory with appropriate early intervention. Patients with a preoperative neurological deficit are at a significant risk of having a permanent deficit. Cite this article: Bone Joint J 2022;104-B(1):103-111.

A Survey of Methods and Technologies Used for Diagnosis of Scoliosis

The purpose of this article is to present diagnostic methods used in the diagnosis of scoliosis in the form of a brief review. This article aims to point out the advantages of select methods. This article focuses on general issues without elaborating on problems strictly related to physiotherapy and treatment methods, which may be the subject of further discussions. By outlining and categorizing each method, we summarize relevant publications that may not only help introduce other researchers to the field but also be a valuable source for studying existing methods, developing new ones or choosing evaluation strategies.

Validation of the concavity-convexity quotient as a new method to measure the magnitude of scoliosis

Objectives

We propose a novel and simple method to determine the magnitude of the curve in scoliosis and its correlation with the Cobb angle.

Methods

Using multiple rounds of nominal group technique and an established consensus-building methodology, a multidisciplinary research group identified a simple method to value the curve deformity based on the vertebral pedicles.

Measurements

A mathematical study was performed to determine the relationship between the Cobb angle and the concavity-convexity quotient (CCQ). To evaluate the clinical correlation between the Cobb angle and CCQ, spine surgeons measured 48 curves (before and after follow-up) of congenital scoliosis.

Results

This quotient reflects the ratio between the distance from the upper end of the most inclined upper vertebra to the lower end of the most inclined lower vertebra on the concave side (A-distance) and the corresponding distance on the convex side of the curve (B-distance). The existing mathematical relationship is based on changing the explicit coordinates to polar coordinates. Finally, the clinical correlation between the Cobb angle and CCQ was statistically significant (r = -0.688; P < 0.001 in first measure and r = -0.789; P < 0.001 in the second measure).

Conclusions

Our study provides Level III evidence that CCQ represents a promising alternative or a complementary method to the traditional Cobb angle due to its simple and reliable ability to measure the magnitude of the curve.

Reproducibility of the classification of early onset scoliosis (C-EOS)

STUDY DESIGN

Reproducibility study.

OBJECTIVES

Assess the agreement and reliability of the classification of early onset scoliosis (C-EOS). C-EOS is a promising tool for patients with early onset scoliosis (EOS). However, the reliability has only been examined without measuring radiographs and not including the annual progression rate (APR) modifier.

METHODS

We included a single-center consecutive cohort of patients diagnosed with EOS seen in our outpatient clinic. Patients had no previous spine surgery. Four raters rated 60 cases. Two anterior-posterior full-spine radiographs, taken minimum 6 months apart, and one sagittal radiograph were measured twice by all raters in a blinded test-retest setup. Results were assessed using crude frequency of overall agreement (OA), intra- and inter-rater Fleiss kappa (κ) statistics, and intraclass correlation coefficient (ICC). We calculated the 95% limits of agreement (LOA) for major curve angle (MCA), kyphosis, and APR using a linear mixed-effects model. Inter- and intra-rater LOA were analyzed for each etiology separately.

RESULTS

Mean age was 8.7 ± 3.4 years and the etiology were congenital/structural (n = 20), idiopathic (n = 19), neuromuscular (n = 13), or syndromic (n = 8). For etiology, OA was 75.8% and κ = 0.80. For major curve angle, OA was 84.2%, κ = 0.86, ICC = 0.97, and LOA = 12.8°. For kyphosis, OA was 55.8%, κ = 0.52, ICC = 0.87, and LOA = 20.6°. For APR, OA was 76.7%, κ = 0.61, ICC = 0.77, and LOA = 17.4°/year. Inter- and intra-rater LOA were generally largest for neuromuscular and smallest for idiopathic patients.

CONCLUSIONS

We found substantial agreement for etiology, however, with disagreement in certain cases. The reliability of MCA was excellent; however, somewhat lower for kyphosis and APR with less accuracy. The measurement errors of MCA, kyphosis, and APR depended largely on the etiology. Regarding APR, LOA exceeded the 10°/year increments proposed in the C-EOS, suggesting a revision of this optional modifier.

LEVEL OF EVIDENCE

Diagnostic study level 1.

Importância da experiência clínica para a mensuração da curva escoliótica de crianças pela técnica de Cobb

RESUMO A escoliose é definida como uma deformidade com desvio lateral da coluna no plano coronal, torsão da coluna e do tronco e distúrbio no perfil sagital. Essa alteração postural é avaliada por meio de radiografia de incidência anteroposterior, utilizando-se o método de Cobb. O objetivo do estudo é verificar a influência da experiência do avaliador sobre a confiabilidade intraexaminador e interexaminador do ângulo Cobb em curvaturas escolióticas de crianças. Foram incluídas na pesquisa 39 crianças portadoras de escoliose idiopática, com idade entre 7 e 18 anos. Os exames foram avaliados por dois fisioterapeutas, um quiropraxista e um estudante de fisioterapia - cada um avaliando duas vezes cada exame. A segunda avaliação ocorreu após sete dias, para confiabilidade intraexaminador. Ademais, as primeiras avaliações forneceram dados para confiabilidade interexaminador. A análise estatística foi realizada com coeficiente de correlação intraclasse (CCI), análise de Bland e Altman e análise descritiva do desvio absoluto médio, erro-padrão de medição e mínima mudança detectável. Observou-se boa confiabilidade (CCI>0,5) para as análises intraexaminadores entre os profissionais, e confiabilidade fraca (CCI=0,4) para o avaliador inexperiente. A confiabilidade interexaminador dos profissionais foi boa (CCI=0,6), e com a presença do avaliador inexperiente foi fraca (CCI=0,3). As avaliações entre os profissionais apresentaram menor variabilidade das medidas e valores de desvio-padrão quando comparadas com as do avaliador inexperiente. A mensuração dos ângulos da escoliose por meio do método de Cobb realizada por profissionais experientes apresentou melhores índices de concordância e de confiabilidade intra e interexaminadores e menor desvio-padrão e variabilidade entre as medidas.

Modified PUMC classification for adolescent idiopathic scoliosis

BACKGROUND

The original Peking Union Medical College (PUMC) classification of adolescent idiopathic scoliosis (AIS) is one system to combine each type with corresponding surgical fusion guidance, presenting comparable interobserver reliability, and reproducibility with Lenke classification. However, during its application in previous over 10 years, we found 2 main problems of this classification, which required modification.

PURPOSE

(1) To evaluate the interobserver and intraobserver reliability, (2) to assess the effects of the added fusion criteria of proximal thoracic (PT) curve on improving postoperative shoulder balance of the modified PUMC classification of AIS.

STUDY DESIGN/SETTING

Retrospective analysis of our AIS cohort and prospective validation of its effectiveness.

PATIENT SAMPLE

Fifty sets of preoperative radiographs of AIS patients were randomly chosen from our AIS database. Furthermore, 46 consecutive AIS cases with PT curve were enrolled who underwent surgeries in our center from July 2007 to July 2013, with at least 2-year follow-up.

OUTCOME MEASURES

The classification results of 50 sets of preoperative radiographs by 5 surgeons. The shoulder balance was evaluated using radiographic shoulder height.

METHODS

Five surgeons independently evaluated and classified presurgical radiographs of 50 AIS patients based on the modified PUMC classification. Inter- and intraobserver reliabilities were calculated. Furthermore, the post-op shoulder balance was investigated in 46 consecutive cases of AIS with PT curve who were treated strictly based on the modified PUMC classification.

RESULTS

The Kappa coefficients of inter- and intraobserver reliability of the overall modified PUMC classification are 0.889 and 0.865, respectively. The Kappa coefficients of inter- and intraobserver reliability for the type II are 0.791 and 0.746, respectively. In addition, the shoulder balance rate of the 46 AIS patients with PT curve at the final follow-up was 95.7%.

CONCLUSIONS

Modified PUMC classification presents incremental improvement compared to our original published version, with high interobserver and intraobserver reliability and better performance of postoperative shoulder balance. Furthermore, the modified PUMC classification provides corresponding surgical fusion guidance for each subtype. Multicenter prospective studies with larger samples are still needed to further improve this system.

LncRNA-SULT1C2A regulates Foxo4 in congenital scoliosis by targeting rno-miR-466c-5p through PI3K-ATK signalling

Congenital scoliosis (CS) is the result of anomalous vertebrae development, but the pathogenesis of CS remains unclear. Long non‐coding RNAs (lncRNAs) have been implicated in embryo development, but their role in CS remains unknown. In this study, we investigated the role and mechanisms of a specific lncRNA, SULT1C2A, in somitogenesis in a rat model of vitamin A deficiency (VAD)‐induced CS. Bioinformatics analysis and quantitative real‐time PCR (qRT‐PCR) indicated that SULT1C2A expression was down‐regulated in VAD group, accompanied by increased expression of rno‐miR‐466c‐5p but decreased expression of Foxo4 and somitogenesis‐related genes such as Pax1, Nkx3‐2 and Sox9 on gestational day (GD) 9. Luciferase reporter and small interfering RNA (siRNA) assays showed that SULT1C2A functioned as a competing endogenous RNA to inhibit rno‐miR‐466c‐5p expression by direct binding, and rno‐miR‐466c‐5p inhibited Foxo4 expression by binding to its 3′ untranslated region (UTR). The spatiotemporal expression of SULT1C2A, rno‐miR‐466c‐5p and Foxo4 axis was dynamically altered on GDs 3, 8, 11, 15 and 21 as detected by qRT‐PCR and northern blot analyses, with parallel changes in Protein kinase B (AKT) phosphorylation and PI3K expression. Taken together, our findings indicate that SULT1C2A enhanced Foxo4 expression by negatively modulating rno‐miR‐466c‐5p expression via the PI3K‐ATK signalling pathway in the rat model of VAD‐CS. Thus, SULT1C2A may be a potential target for treating CS.

Intraobserver and Interobserver Measurement Variability of the Rib-Vertebral Angle Difference

BACKGROUND

The rib-vertebral angle (RVAD) differentiates between progressive and resolving infantile idiopathic scoliosis (IIS) curves. Those with a RVAD<20 degrees often resolve without treatment, whereas those >20 degrees often progress and require treatment. The mathematical magnitude of RVAD measurement variability has not been described, and was thus the purpose of this study. It is important to know the reliability of RVAD measurements so as to understand changes that can be attributed to observer error alone.

PURPOSE

The purpose of the study was to mathematically determine the intraobserver and interobserver measurement variability of the RVAD difference in IIS.

METHODS

A convenience sample of 50 patients with IIS was selected. The RVAD was measured twice by 7 different observers separated by a minimum of 3 weeks. The 7 different readers chosen to measure the RVAD were 2 orthopaedic residents, 1 pediatric radiologist, and 4 attending pediatric orthopaedic surgeons. The same goniometer was used for all measurements. Intraobserver and interobserver measurement variability was determined using 3 well known used statistical methods.

RESULTS

The 3 different methods used to determine intraobserver and interobserver variability using 95% prediction/confidence limits gave very similar results. Intraobserver variability was ∼24 degrees and the interobserver variability was ∼23 degrees.

DISCUSSION

The utility of the RVAD in medical decision-making and counseling of patients with IIS should be approached with caution when used in isolation due to the large measurement variability.

LEVEL OF EVIDENCE

Level 3.

Reliability analysis of Cobb measurement in degenerative lumbar scoliosis using endplate versus pedicle as bony landmarks

OBJECTIVES

Degenerative changes of endplates in older patients and tilting of vertebral body in lumbosacral lordosis could make an accurate identification of endplates for the Cobb measurement difficult. Pedicles have been proposed as alternative landmarks because they are usually better visualized, and offer similar clinical validity to the endplates. The objective of this study was to investigate the reliability of the pedicle method of Cobb measurement in degenerative lumbar scoliosis and compare it with the traditional endplate method.

METHODS

Two hundred and eighty-four radiographs of degenerative lumbar scoliosis were evaluated. The radiographs were classified into groups based on the patient's age (< 60 years, 60 to 80 years, and > 80 years), level of lower end vertebra (LEV) (LEV at L5, and LEV at or above L4), and curve severity (< 20°, 20° to 40°, and > 40°). Three observers independently measured the radiographs using the endplate and pedicle methods twice with an interval of 1 week. The intra- and interobserver reliabilities were calculated using intraclass correlation coefficients (ICC).

RESULTS

The intra- and interobserver ICC values were better for all observers in the > 80 years age group using the pedicle method. The intraobserver ICC values of pedicle method were also better in the LEV at L5 group, and the interobserver ICC values showed a slightly better consistency with the pedicle method. For patients with > 40° curves, the intraobserver ICC values for all observers as well as interobserver ICC values were better using the endplate method.

CONCLUSION

The reliabilities of the endplate and pedicle methods for degenerative lumbar scoliosis were both excellent. The pedicle method might be better in older patients (> 80 years) and those with LEV at L5; while the endplate method could have some strength in severe cases (> 40°).

The Effect of Botulinum Toxin A Injections in the Spine Muscles for Cerebral Palsy Scoliosis, Examined in a Prospective, Randomized Triple-blinded Study

STUDY DESIGN

A prospective, randomized triple-blinded cross-over design treating with either botulinum toxin A (BXT) or saline (NaCl).

OBJECTIVE

To examine the efficacy of BTX treatment in cerebral palsy scoliosis (CPS).

SUMMARY OF BACKGROUND DATA

Intramuscular injections with BTX have been used off label in treating CPS. 1 prospective study has been conducted, demonstrating in both radiological and clinical improvement, whereas showing no side effects or complications.

METHODS

Subjects (brace-treated CPS between 2 and 18 yr) were injected using ultrasonic-guidance with either NaCl or BTX in selected spine muscles with 6 mo intervals (block randomization, sealed envelope). Radiographs of the spine and clinical follow-up were captured before and 6 weeks after each injection. Primary outcome parameter was radiological change in Cobb angle, where a 7° change was regarded as an effect (1 SD). Radiological parameters were measured before and 6 weeks after treatment by 3 experienced doctors separately. Moreover, clinical results were evaluated by the pediatric quality of life score and systematic open questioning of the parents about the child's wellbeing. Subjects, researchers, and monitors were blinded during the trial. Appropriate permissions (2008-004584-19) and no funding were obtained.

RESULTS

16 cerebral palsy patients (GFMCS III-V) with CPS were consecutively included, whereas 6 patients were excluded. There were no drop-outs to follow-up, but 1 possible serious adverse event of pneumonia resulting in death was recorded and the study was terminated. No significant radiological or clinical changes were detected when compared with NaCl injections using Wilcoxon matched pair signed-rank test.

CONCLUSION

No positive radiological or clinical effects were demonstrated by this treatment, except for the parent's initial subjective but positive appraisal of the effect. However, the study was terminated due to 1 possible severe adverse event and scheduled numbers needed to treat (hence power) were not reached.

LEVEL OF EVIDENCE

1.

Reliability analysis of Cobb angle measurements of congenital scoliosis using X-ray and 3D-CT images

PURPOSE

Therapeutic decisions for congenital scoliosis rely on Cobb angle measurements on consecutive radiographs. There have been no studies documenting the variability of measuring the Cobb angle using 3D-CT images in children with congenital scoliosis. The purpose of this study was to compare the reliability and measurement errors using X-ray images and those utilizing 3D-CT images.

MATERIALS AND METHODS

The X-ray and 3D-CT images of 20 patients diagnosed with congenital scoliosis were used to assess the reliability of the digital 3D-CT images for the measurement of the Cobb angle. Thirteen observers performed the measurements, and each image was analyzed by each observer twice with a minimum interval of 1 week between measurements. The analysis of intraobserver variation was expressed as the mean absolute difference (MAD) and standard deviation (SD) between measurements and the intraclass correlation coefficient (IaCC) of the measurements. In addition, the interobserver variation was expressed as the MAD and interclass correlation coefficient (IeCC).

RESULTS

The average MAD and SD was 4.5° and 3.2° by the X-ray method and 3.7° and 2.6° by the 3D-CT method. The intraobserver and interobserver intraclass ICCs were excellent in both methods (X-ray: IaCC 0.835-0.994 IeCC 0.847, 3D-CT: IaCC 0.819-0.996 IeCC 0.893). There was no significant MAD difference between X-ray and 3D-CT images in measuring each type of congenital scoliosis by each observer.

CONCLUSIONS

Results of Cobb angle measurements in patients with congenital scoliosis using X-ray images in the frontal plane could be reproduced with almost the same measurement variance (3°-4° measurement error) using 3D-CT images. This suggests that X-ray images are clinically useful for assessing any type of congenital scoliosis about measuring the Cobb angle alone. However, since 3D-CT can provide more detailed images of the anterior and posterior components of malformed vertebrae, the volume of information that can be obtained by evaluating them has contributed greatly to the development of strategies for the surgical treatment of congenital scoliosis.

A New Technique to Increase Reliability in Measuring the Axis of Bone

Measuring bone angles is an important method for diagnosing disease and predicting the prognosis in orthopedics. Traditionally, the angle is measured using lines drawn manually and adjusted by the naked eye. The purpose of the present study was to propose new methods to measure the bone angles formed by the axes of the calcaneus with good reliability and low operational error. The 2 new methods used linear regression analysis of the points inside and on the "envelope" line. The traditional method used the vector of the lines drawn for calculation. Digital radiographs of the lateral view of the feet from 51 patients were collected, and the angles were measured using these 3 methods. Next, we analyzed the reliability, differences, and correlations of these 3 methods. The intra- and interobserver comparisons revealed significant differences between the results of the 2 new methods and those of the traditional method. In addition, the new methods had greater reliability and better intra- and interobserver correlations than did the traditional method. We suggest that these 2 new methods to measure bone axis should be added to the Picture Archiving and Communication System to obtain more reliable and standardized data in clinical practice and for future research purposes.

Measurement Variability in the Evaluation of the Proximal Junction in Distraction-based Growing Rods Patients

BACKGROUND

Proximal junctional kyphosis (PJK) is a known complication of spinal fusion and has been shown to occur in the setting of growing rod instrumentation. Previous studies have shown good reliability in measuring PJK in adolescent idiopathic scoliosis.

METHODS

Four pediatric orthopaedic spine surgeons measured the proximal junction in 10 patients with growing rod instrumentation using 2 methods. In method 1, measurements were made from the inferior endplate of the upper instrumented vertebrae (UIV) to the superior endplate of 1 level above the UIV. In method 2, measurements were made from the inferior endplate 2 levels below the UIV to the superior endplate 2 levels above the UIV. These measurements were repeated 1 week later.

RESULTS

Method 1 had an intraobserver variability of ±13.2 degrees and interobserver variability of ±21.6 degrees, whereas method 2 had an intraobserver variability of ±18.3 degrees and interobserver variability of ±20.7 degrees.

CONCLUSIONS

Interobserver variability of PJK is >20 degrees. As PJK is commonly defined as >10 degrees of kyphosis above the UIV, measurement of PJK in patients with distraction-based growing rods on lateral radiographs has too much variability to be useful.

LEVEL OF EVIDENCE

Level III-diagnostic studies.

Comparison between Oxford Cobbmeter and digital Cobbmeter for measurement of Cobb angle in adolescent idiopathic scoliosis

PURPOSE

The purpose of this study was to compare Cobb angle measurements performed using an Oxford Cobbmeter and digital Cobbmeter in a series of 20 adolescent idiopathic scoliosis (AIS) patients.

METHODS

Four observers measured major Cobb angles on 20 standing postero-anterior radiographs of AIS patients with both Oxford Cobbmeter and digital Cobbmeter (iPhone Cobbmeter Application). The measurements were repeated a week after the original measurements.

RESULTS

The mean Cobb angle in this study was 43.6° ± 23.62°. The mean measurement time for an observer to measure the 20 Cobb angles was 24.9 min for the smart phone compared with 25.6 min for the Oxford Cobbmeter. The 95 % confidence interval for differences between smart phone and Oxford Cobbmeter measurements on the same radiograph was ±3.68°. The intra-observer variability of the smart phone is equivalent to the Oxford Cobbmeter. The 95 % confidence intervals for inter-observer error were ±5° and ±5.8° for the smart phone and Oxford Cobbmeter, respectively.

CONCLUSIONS

We conclude that the smart phone with integrated Tiltmeter and Cobbmeter application is an equivalent Cobb measurement tool to the Oxford Cobbmeter. The advantages of smart phone are the accuracy of determining the most inclined vertebrae and accordingly more precise Cobb angle measurement. The new smart phones with these integrated applications may be really helpful to the spine surgeons, especially in hospitals where PACS or Oxford Cobbmeter is not available.

Reliability of Coronal Curvature Measures in Premature Scoliosis: Comparison of 4 Methods Using Inverted Digital Luminescence Radiography

STUDY DESIGN

Observational study with 4 examiners.

OBJECTIVE

To improve the reproducibility and reliability of coronal curvature measurements.

SUMMARY OF BACKGROUND DATA

Several different methods have been developed to measure coronal curvature. Inverted digital luminescence radiography may be an additional technique to improve the reliability of measurement methods.

METHODS

A total of 114 whole spine posterior-anterior radiographs were collected to compare the reliability of 4 measurement methods used in early onset scoliosis. Each radiograph was measured twice by each of 4 examiners using 4 measurement methods with normal and inversion views. Data were analyzed to determine inter- and intraobserver reliabilities.

RESULTS

For all 4 methods, the overall intraobserver ICCs were greater than 0.926 and the interobserver ICCs were greater than 0.902, indicating excellent reliability. When intraobserver reliability was assessed in relation to scoliosis severity (<20°, 20°-40°, and >40°), the ICCs were higher for greater degrees of curvature; nonetheless, these values were in the excellent range for all methods and were higher for inversion (>0.908) than normal (>0.838) radiographs. For interobserver comparisons, the ICCs were better for the pedicle method (normal: >0.795, inversion: >0.831) than for the other methods (normal: >0.532, inversion: >0.590), with inverted digital luminescence radiography showing the higher ICCs.

CONCLUSION

Inversion radiographs showed high reliability and may increase reliability in cases of less deformed spines. In addition, the pedicle method led to higher ICCs for all measurements regardless of severity, especially on inversion radiographs.

LEVEL OF EVIDENCE

2.

Manual and computerized measurement of coronal vertebral inclination on MRI images: a pilot study

AIM

A pilot study that presents a systematic approach for evaluating the variability of manual and computerized measurements of coronal vertebral inclination (CVI) on images acquired by magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Three observers identified the vertebral body corners of 28 vertebrae on two occasions on two-dimensional (2D) coronal MRI cross-sections, which served to evaluate CVI using six manual measurements (superior and inferior tangents, left and right tangents, mid-endplate and mid-wall lines). Computerized measurements were performed by evaluating CVI from the symmetry of vertebral anatomical structures of the same 28 vertebrae in 2D coronal MRI cross-sections and in three-dimensional (3D) MRI images.

RESULTS

In terms of standard deviation (SD), the mid-endplate lines proved to be the manual measurements with the lowest intra- (1.0° SD) and interobserver (1.4° SD) variability. The computerized measurements in 3D yielded even lower intra- (0.8° SD) and interobserver (1.3° SD) variability. The strongest inter-method agreement (1.2° SD) was found among lines parallel to vertebral endplates (superior tangents, inferior tangents, mid-endplate lines). The computerized measurements in 3D were most in agreement with the mid-endplate lines (1.9° SD). The estimated intra- and interobserver variabilities of standard Cobb angle measurements were equal to 1.6° SD and 2.5° SD, respectively, for manual measurements, and to 1.1° SD and 1.8° SD, respectively, for computerized measurements.

CONCLUSION

The mid-endplate lines proved to be the most reproducible and reliable manual CVI measurements. Computerized CVI measurements based on the evaluation of the symmetry of vertebral anatomical structures in 3D were more reproducible and reliable than manual measurements.

Centroid method: an alternative method of determining coronal curvature in scoliosis. A comparative study versus Cobb method in the degenerative spine

BACKGROUND CONTEXT

Although the Cobb method is considered the gold standard, the centroid method may offer a reasonable alternative in adult scoliosis because it has better inter- and intraobserver reliabilities in adolescent scoliosis.

PURPOSE

To compare the reliabilities of the Cobb and the centroid methods for measuring coronal curvature in degenerative scoliosis in older patients.

STUDY DESIGN

Observational study involving three examiners.

PATIENT SAMPLE

Sixty whole spine posteroanterior (PA) radiographs were collected.

OUTCOME MEASURES

Data were analyzed to determine inter- and intraobserver reliabilities.

METHODS

Sixty whole spine PA radiographs of patients older than 60 years were collected to compare the reliabilities of the centroid and the Cobb methods for measuring coronal curvature in degenerative scoliosis. Three examiners using both methods independently measured radiographs twice. Data were analyzed to determine inter- and intraobserver reliabilities.

RESULTS

Intraobserver comparisons of all the 60 radiographs revealed that inter- and intraclass correlation coefficients (ICCs) of the Cobb and the centroid methods were both excellent (greater than 0.979 vs. greater than 0.918), and mean absolute differences (MADs) were similar (less than 1.58 vs. less than 2.02). In interobserver comparisons, ICCs of the Cobb method were higher than that of the centroid method (greater than 0.922 vs. greater than 0.799), and the MADs of the Cobb method were lower than that of the centroid method (less than 2.91 vs. less than 4.84). Comparisons of radiographs subdivided by severity showed that the ICCs of the Cobb and the centroid methods were both excellent (greater than 0.819 vs. greater than 0.801), and their MADs were similar (less than 2.29 vs. less than 2.53) for intraobserver comparisons. Interobserver comparisons showed that ICCs and MADs were dependent on the severity of coronal curvature, and the ICCs of the Cobb method (greater than 0.698) were greater than that of the centroid method (greater than 0.507). Furthermore, MAD values for the Cobb method were lower than that for the centroid method (less than 3.59 vs. less than 6.07). Moreover, these results are contradictory to the previous study, which showed the higher reliability of the centroid method in measures of adolescent scoliosis.

CONCLUSIONS

In the present study, the reliability of the centroid method was found to be more susceptible to the severity of disease in older patients, despite its demonstrated greater reliability in adolescent scoliosis. Our findings show that the selective use of these two methods in old and young patients can increase the reliabilities of measurements made.

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.

Reliability of the measurement of thoracolumbar burst fracture kyphosis with Cobb angle, Gardner angle, and sagittal index

INTRODUCTION

Kyphotic deformity plays a key role in our evaluation of patients with thoracolumbar burst fracture, and there are several variables available for kyphotic deformity assessment, including Cobb angle, Gardner angle, and sagittal index. However, it remains unknown about intra- and inter-observer variability of sagittal index.

AIM

The purpose of this study is to determine the reliability of the measurement for thoracolumbar burst fracture kyphosis using Cobb angle, Gardner angle, and sagittal index. Thirty-five patients with thorocolumbar burst fractures treated in our institute were identified. The lateral spine radiographs and midsagittal CT images of the 35 patients were measured on two separate occasions, in random order, by five attending spine surgeons using Cobb angle, Gardner angle, and sagittal index.

METHOD

We statistically assessed the agreement, the intra-observer and the inter-observer reliability of the three methods. The intra-observer reliability is always better than the inter-observer reliability, regardless of the parameter being measured or the imaging modality.

RESULTS

Intra-class correlation coefficients (ICC) were the most consistent for Cobb angle, followed by Gardner angle and sagittal index. Midsagittal CT images had better intra- and inter-observer reliabilities than lateral plain radiography. Also, agreement was better using midsagittal CT images as compared with lateral plain radiography.

CONCLUSION

The results of our study suggest that Cobb angle is the most consistent in terms of intra- and inter-observer reliabilities in the assessment of thoracolumbar burst fracture kyphosis.

A Kohonen neural network description of scoliosis fused regions and their corresponding Lenke classification

PURPOSE

Surgical instrumentation for adolescent idiopathic scoliosis (AIS) is a complex procedure where selection of the appropriate curve segment to fuse, i.e., fusion region, is a challenging decision in scoliosis surgery. Currently, the Lenke classification model is used for fusion region evaluation and surgical planning. Retrospective evaluation of Lenke classification and fusion region results was performed.

METHODS

Using a database of 1,776 surgically treated AIS cases, we investigated a topologically ordered self organizing Kohonen network, trained using Cobb angle measurements, to determine the relationship between the Lenke class and the fusion region selection. Specifically, the purpose was twofold (1) produce two spatially matched maps, one of Lenke classes and the other of fusion regions, and (2) associate these two maps to determine where the Lenke classes correlate with the fused spine regions.

RESULTS

Topologically ordered maps obtained using a multi-center database of surgically treated AIS cases, show that the recommended fusion region agrees with the Lenke class except near boundaries between Lenke map classes. Overall agreement was 88%.

CONCLUSION

The Lenke classification and fusion region agree in the majority of adolescent idiopathic scoliosis when reviewed retrospectively. The results indicate the need for spinal fixation instrumentation variation associated with the Lenke classification.

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.

Use of the iPhone for Cobb angle measurement in scoliosis

PURPOSE

The Cobb technique is the universally accepted method for measuring the severity of spinal deformities. Traditionally, Cobb angles have been measured using protractor and pencil on hardcopy radiographic films. The new generation of mobile 'smartphones' make accurate angle measurement possible using an integrated accelerometer, providing a potentially useful clinical tool for assessing Cobb angles. The purpose of this study was to compare Cobb angle measurements performed using a smartphone and traditional protractor in a series of 20 adolescent idiopathic scoliosis patients.

METHODS

Seven observers measured major Cobb angles on 20 pre-operative postero-anterior radiographs of Adolescent Idiopathic Scoliosis patients with both a standard protractor and using an Apple iPhone. Five of the observers repeated the measurements at least a week after the original measurements.

RESULTS

The mean absolute difference between pairs of smartphone/protractor measurements was 2.1°, with a small (1°) bias toward lower Cobb angles with the iPhone. 95% confidence intervals for intra-observer variability were ±3.3° for the protractor and ±3.9° for the iPhone. 95% confidence intervals for inter-observer variability were ±8.3° for the iPhone and ±7.1° for the protractor. Both of these confidence intervals were within the range of previously published Cobb measurement studies.

CONCLUSIONS

We conclude that the iPhone is an equivalent Cobb measurement tool to the manual protractor, and measurement times are about 15% less. The widespread availability of inclinometer-equipped mobile phones and the ability to store measurements in later versions of the angle measurement software may make these new technologies attractive for clinical measurement applications.

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.

Outcomes after spinal fusion for congenital scoliosis: instrumented versus uninstrumented spinal fusion

STUDY DESIGN

retrospective case-control study.

OBJECTIVE

to compare radiographic and clinical outcomes in children with congenital scoliosis who had either instrumented or uninstrumented spinal fusion. SUMMARY OF BACKGROUND DATA.: Three previous studies have examined patients with spinal fusion for congenital scoliosis. Two have small case numbers with only short-term follow-up and the third is a large series without clinical outcomes.

METHODS

after approval from the authors' institutional review board, children who underwent instrumented or uninstrumented spinal fusion for congenital scoliosis were identified. All curves were measured before surgery, after surgery, and annually until final follow-up and the initial postoperative curve correction and the final curve correction were calculated. All patients were sent a Scoliosis Research Society-22 (SRS-22) outcomes instrument to complete at final follow-up.

RESULTS

a total of 51 subjects were identified. Thirty children were included in the instrumented group and 21 were in the uninstrumented group. For each child, the preoperative curves of the highest magnitude averaged 50° in the instrumented group and 46° in the uninstrumented group. Initial postoperative curve correction averaged 21° in the instrumented group and 4° in the uninstrumented group. At final follow-up, the curves had a mean progression of 10° from initial postoperative Cobb angles in the instrumented group and 8° in the uninstrumented group, or an average of 2° of progression per year from the initial postoperative curve correction in both groups compared with the postoperative curves. The total mean SRS-22 score for the instrumented group was 3.8 ± 0.8 and for the uninstrumented group was 4.1 ± 0.8. There was no difference between the two groups in the categories of function, pain, self-image, mental health, and satisfaction.

CONCLUSION

we were unable to distinguish between the two groups, using radiographic and clinical (patient-reported) outcome measures except that there was a difference in immediate postoperative curve correction between the two groups. Subjects in both groups showed postoperative curve progression at 2- to 14-year follow-up, but patients reported high-functioning clinical outcomes.

LEVEL OF EVIDENCE

Therapeutic level III.

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.

Interobserver and intraobserver reliability of Cobb angle measurement: endplate versus pedicle as bony landmarks for measurement: a statistical analysis

BACKGROUND

The Cobb-Lippman technique measures the curve severity by measuring the angle between the upper and lower endplates of the upper-end and lower-end vertebrae, respectively, using pedicles to measure the angle when they are better visualized than the endplates. Vertebral endplates in younger children provide less distinct bony landmarks and pedicles may be more easily identifiable in these children. The purpose of this study is to evaluate the reliability of the pedicle method of the Cobb angle measurement and compare it with the conventional endplate method of measurement.

METHODS

Three hundred and eighteen whole spine preoperative anteroposterior radiograms of children with varying degrees of idiopathic scoliosis involving the thoracic spine were evaluated. These radiograms were grouped based on the child's age (<7 y, 7 to 10 y and >10 y), the position of the upper-end vertebra (upper-end vertebra at or above T5 and upper-end vertebra caudal to T5), and based on curve severity (mild, <20 degrees; moderate 20 to 40 degrees, and severe>40 degrees). Three observers independently examined the radiograms using the endplate method and the pedicle method 3 times each using the digitized computer system. Both intraobserver and interobserver agreements were accessed by calculating the intraclass correlation coefficient (ICCC). In addition, a Bland-Altman plot was made in which the strength of the relationship between the score differences and their mean was indicated by the slope of a regression line.

RESULTS

The single ICCC values were better for all observers for <7-year age group using the pedicle method, indicating lesser intraobserver variability. The average ICCC values, indicating interobserver variability, were similar for all age groups. All the ICCC values lay in the excellent or substantial group. Tests for significance showed no significant difference between the 2 methods of measurement.

CONCLUSIONS

Differences in measurement values with the pedicle method and end-plate method of measurement of the Cobb angle are not statistically significant. Either method can be used for measurement when using a computer-digitized system, which may have helped to minimize measurement discrepancies between these 2 methods.

LEVEL OF EVIDENCE

Diagnostic studies, investigating a diagnostic test, level 1.

Scoliosis secondary to a hemivertebra: seven patients with gradual improvement without treatment

STUDY DESIGN

Retrospective case series.

OBJECTIVE

To make clinicians aware of this unusual natural history.

SUMMARY OF BACKGROUND DATA

Nonprogressive and progressive scolioses due to hemivertebrae have been abundantly documented in the literature. There has been no article describing spontaneous improvement. Two case reports have been described elsewhere in a general article on natural history.

METHODS

From a previous review of 1250 patients with congenital spine deformity of all types, 7 patients were identified with spontaneous improvement of their scoliosis due to a hemivertebra during growth.

RESULTS

The mean curve at start of observation was 31 degrees (range: 24 degrees -43 degrees), and at the end of observation was 19 degrees (range: 10 degrees -30 degrees). Six of the curves were at the thoracolumbar region (T11-L2), and the other at T1. The average duration of follow-up was 9 years.

CONCLUSION

Spontaneous curve improvement is rare, but possible. In view of the difficulty of prediction for curves due to a hemivertebra, careful observation with careful curve measurement is recommended. Inappropriate early, aggressive surgery should be avoided.

Update on congenital spinal deformities: preoperative evaluation

STUDY DESIGN

Review.

OBJECTIVE

To review and outline the preoperative evaluation and approach in assessing children with congenital vertebral malformation.

SUMMARY OF BACKGROUND DATA

Congenital vertebral malformations encompass a broad spectrum of conditions. A high association of renal, cardiac, and intraspinal anomalies with congenital vertebral malformation has been well documented in the literature. Vertebral malformation with involvement of the thoracic cage may lead to the development of thoracic insufficiency. The natural history, the character, and location of the deformity ultimately influence the propensity for progression and the necessity for treatment. Multiple factors should be considered before treatment with the goal of treatment aimed at providing the best possible care to be able to optimize the child's overall function and potential for growth.

METHODS

Narrative and review of literature.

CONCLUSION

Congenital scoliosis is a multifaceted condition. The presentation of the condition can be quite varied from those presenting with an isolated hemivertebrae to those with severe malformations, complicated by multiple medical conditions. A thorough preoperative evaluation is necessary before the institution of any treatment protocol. The presence of any medical condition must be addressed; the treatment should be tailor-made for each patient putting into consideration the patients' age and the effects of treatment on pulmonary function at maturity.

A review of methods for quantitative evaluation of spinal curvature

The aim of this paper is to provide a complete overview of the existing methods for quantitative evaluation of spinal curvature from medical images, and to summarize the relevant publications, which may not only assist in the introduction of other researchers to the field, but also be a valuable resource for studying the existing methods or developing new methods and evaluation strategies. Key evaluation issues and future considerations, supported by the results of the overview, are also discussed.

Accuracy and repeatability of a new method for measuring scoliosis curvature

STUDY DESIGN

A prospective diagnostic clinical trial.

OBJECTIVE

To evaluate the accuracy, repeatability of a new method for measuring spinal curvature in patients with scoliosis, the axis-line-distance technique (ALDT), in comparison with the Cobb method.

SUMMARY OF BACKGROUND DATA

Timely and accurate determination of the degree of lateral curvature of the spine is essential for deciding the appropriate treatment method for scoliosis. Although the Cobb method has been accepted as the clinical standard for 60 years, many investigators have reported a high degree of variance in the measurements of spinal curvature obtained using this method. Therefore, the development of an alternative method that incorporates the advances in imaging technology and assessment is needed.

METHODS

Sixty-five scoliosis patients were evaluated by 6 physician observers. The spinal curves were measured on 2 separate occasions using the Cobb method and the ALDT on a picture archiving and communication system workstation. The time interval between the 2 measurements was 3 weeks, and the data were analyzed by a paired-sample Student t test and Pearson correlation method using SPSS 12.0 software package.

RESULTS

Intraobserver variance of the 2 measurements, the minimum variance, the maximum variance, and the mean and standard deviation values were 0 degrees, 26 degrees, and 5.14 degrees +/- 0.69 degrees for the Cobb method, and 0 mm, 20 mm, and 2.55 +/- 0.38 mm for the ALDT, respectively. There was a significant intraobserver difference in the Cobb angle measurements among 3 of the 6 observers (P < 0.05). No significant intraobserver variance in ALDT measurements was detected. The mean interobserver measurement variance for the Cobb method was 6.54 degrees +/- 1.35 degrees, significantly greater than that for the ALDT (3.58 +/- 0.93 mm; P < 0.05). There were significant positive correlation between the ALDT and the Cobb measurements (r = 0.73, P < 0.05).

CONCLUSION

The ALDT is more reliable, reproducible, and straightforward, and less error-prone than the Cobb method for measurements of spinal curvature.

Observer reliability between juvenile and adolescent idiopathic scoliosis in measurement of stable Cobb's angle

It is a measurement of Cobb's angles between adolescent (AIS) and juvenile (JIS) idiopathic scoliosis who had stable curves (variation <5 degrees) in more than three visits. Main objective of this paper is to measure inter- and intra-observer reliability of measurements between AIS and JIS who had stable curves in regular follow-up. Twenty-nine JIS and 44 AIS patients who had stable curves without bracing were identified using PACS system. Two observers independently measured Cobb's angle twice on first, during follow-up and final radiogram using computer-based digital radiogram. Both observers were given pre-decided level of upper and lower end plates. Inter- and intra-observer reliability of the measurement was calculated using Pearson correlation-coefficient test between JIS and AIS group. There was no significant difference in Cobb's angle in all measurements by both observers either in JIS (p = 0.756, range 0.706-0.815; ANOVA) or AIS (p = 0.871, range 0.795-0.929; ANOVA) group which suggested that there is no significant difference in Cobb's angle in repeated measurements. Intra-observer reliability for JIS (r = 0.600, range 0.521-0.751; Pearson test) was less than AIS (r = 0.969, range 0.943-0.984; Pearson test); and similarly, inter-observer reliability for JIS (r = 0.547, Pearson test) was also less than AIS (r = 0.961, Pearson test) which indicates that Cobb's angle measurement is less reliable in patients who have juvenile idiopathic scoliosis. Using the identical condition for measurements in both the groups, we could find only one reason for less reliability in JIS group and that is poor demarcation of the vertebral end-plates in this group. This poor inter- and intra-observer reliability in JIS due to ill-defined endplates can be reduced by measuring all previous curves along with latest curves at the same time during the follow-up of patients with JIS to decide about the progression of curves and treatment options.

The effect of mid-thoracic VEPTR opening wedge thoracostomy on cervical tilt associated with congenital thoracic scoliosis in patients with thoracic insufficiency syndrome

STUDY DESIGN

Prospective clinical trial of vertical expandable prosthetic titanium rib (VEPTR) surgery in patients with congenital thoracic scoliosis with thoracic insufficiency syndrome and cervical tilt.

OBJECTIVE

Report efficacy and safety of VEPTR mid-thoracic opening wedge thoracostomy in treatment of cervical tilt and head/truncal decompensation in children with thoracic insufficiency syndrome associated with thoracic congenital scoliosis.

SUMMARY OF BACKGROUND DATA

Cervical tilt in children is a rare problem, usually associated with congenital cervical or cervical-thoracic scoliosis, and in progressive deformity, surgical fusion or hemi-vertebrectomy risks neurologic injury, loss of motion of the cervical spine, and unknown effect on pulmonary function. VEPTR patients with congenital scoliosis can have severe neck tilt with poor cosmesis, with the risk of neck pain in adulthood. VEPTR mid-thoracic opening wedge thoracostomy treats thoracic insufficiency syndrome, and paradoxically also appears to improve the neck alignment cosmesis.

MATERIALS METHODS

Patients with fused ribs and congenital scoliosis, thoracic insufficiency syndrome, and cervical tilt were treated with VEPTR mid-thoracic thoracostomy. Complication rates, respiratory outcome, pulmonary function tests in older children, Cobb angles, head/truncal decompensation, T1 oblique take-off, space available for lung, height of the thoracic spine, and cervical tilt angle were measured.

RESULTS

Fourteen patients with cervical tilt, fused ribs, progressive congenital scoliosis, and TIS were treated. The primary thoracic scoliosis and space available for lung improved, cervical tilt stabilized, and head and truncal decompensation improved. One child was weaned off a ventilator. Complications included device migration, infection, and transient brachial palsy.

CONCLUSION

Mid-thoracic VEPTR opening wedge thoracostomy can stabilize cervical tilt associated with thoracic congenital scoliosis and fused ribs and may be an alternative to cervicothoracic spine fusion or hemi-vertebrectomy in some young children.

Evidence basis for management of spine and chest wall deformities in children

STUDY DESIGN

: Review of relevant studies, including levels of evidence.

OBJECTIVE

: To review research on growth of the spine and chest wall and treatment of deformities. To place this knowledge in context of evidence-based assessment.

SUMMARY OF BACKGROUND DATA

: Knowledge of the growth of the spine, chest wall, and lung in the normal and deformity states has evolved among independent specialties over the past 60 years. Interest in the interrelationship has blossomed as more tools for assessment and treatment have developed. Spine-based and chest wall-based treatment options now exist, as well as options of resection versus gradual distraction.

METHODS

: Peer-reviewed research published on the growth of the spine, lung, chest wall, and treatment of their deformities was reviewed. Treatment methods and outcomes were compared. Ranking of the levels of evidence was performed where possible.

RESULTS

: Most studies of these topics are Level III and IV studies, consisting of case-control studies and case series. This limitation arises because of the rarity and heterogeneity of the disorders affecting the growing spine and chest wall. The natural history of most types of spinal/chest wall deformities is not known with accuracy. Some experimental evidence informs the treatments which involve modulation of the growth of the spine. However, accurate models of the deformities themselves are lacking. Improvements in imaging and measurement offer options for more accurate patient comparison.

CONCLUSION

: The natural history and results of treatment of deformities of the spine and chest wall offer much opportunity for further evidence-based research.

Reliability of radiographic parameters in neuromuscular scoliosis

STUDY DESIGN

Retrospective review of radiographic data.

OBJECTIVES

This study sought to define interobserver and intraobserver variability to further delineate reliable means by which radiographs of patients with neuromuscular scoliosis can be examined.

SUMMARY OF BACKGROUND DATA

Previous studies analyzed the use of Cobb angles in the measurement of idiopathic and congenital scoliosis, but no study until now describes a critical analysis of measurement in evaluating neuromuscular scoliosis.

METHODS

Forty-eight patients with neuromuscular scoliosis radiographs were reviewed. These were evaluated for Cobb angle, end vertebrae selection, Ferguson angle, apex of the curve, C7 balance, pelvic obliquity, Risser sign, status of the triradiate cartilage, kyphosis Cobb angle, endplate selection for kyphosis, and kyphotic index. Interclass and intraclass variability was examined with statistical analysis.

RESULTS

Cobb angle had an intraobserver variability was 5.7 degrees and the interobserver variability was 14.8 degrees . The intraobserver and interobserver variability for Ferguson angle was 6.8 degrees and 20.6 degrees, respectively. The kyphotic Cobb angle intraobserver variability was found to be 17.4 degrees, and the interobserver variability was 24.01 degrees .

CONCLUSIONS

Neuromuscular scoliosis radiographs can be reliably analyzed with the use of Cobb angle. Other forms of analysis, such as Ferguson angle, are not as reliable. Pelvic obliquity should be measured from the horizontal, as other methods are not as reliable. Kyphosis is best evaluated with the use of the kyphotic Cobb angle. Finally, it is felt that a separate anteroposterior pelvis radiograph should be used to assess skeletal maturity, as scoliosis films often truncate the vital anatomy necessary to determine skeletal maturity.

Comparison of Cobb angle measurement of scoliosis radiographs with preselected end vertebrae: traditional versus digital acquisition

STUDY DESIGN

Prospective study.

OBJECTIVE

To compare variability in Cobb angle between digitally and traditionally acquired scoliosis radiographs.

SUMMARY OF BACKGROUND DATA

Previous studies have shown that the 95% confidence interval for Cobb angle can vary from 2.6 degrees to 8.8 degrees. No study directly comparing Cobb angles measured from traditional and digitally acquired radiographs has been reported.

METHODS

A spine model simulating 25 single right thoracic curves (range, 20 degrees-60 degrees) was imaged using traditional and digital techniques. Traditional films and miniaturized printed digital films were each measured twice manually. Digital films were also measured twice using computer imaging software.

RESULTS

Overall mean angle and (95% confidence interval) were 41.7 degrees (39.1 degrees-44.3 degrees) for traditional, 40.6 degrees (37.4 degrees-43.8 degrees) for digital, and 39.7 degrees (36.3 degrees-43.1 degrees) for computer measurements. Overall correlation was 0.994 for traditional and digital, 0.987 for traditional and computer, and 0.993 for digital and computer. Fixed effect model analysis demonstrated that, although a statistically significant difference existed between the 3 methods of measuring the Cobb angle (P < 0.0001), the difference between methods was less than 2 degrees.

CONCLUSIONS

Any of the 3 evaluated methods of measurement can be used to measure Cobb angles. Additionally, the methods can be used interchangeably.

Statistics in orthopaedic papers

Although the importance of sound statistical principles in the design and analysis of data has gained prominence in recent years, biostatistics, the application of statistics to the analysis of biological and medical data, is still a subject which is poorly understood and often mishandled. This review introduces, in the context of orthopaedic research, the terminology and the principles involved in simple data analysis, and outlines areas of medical statistics that have gained prominence in recent years. It also lists and provides an insight into some of the more common errors that occur in published orthopaedic journals and which are frequently encountered at the review stage in papers submitted to the Journal of Bone and Joint Surgery.

Variability in Cobb angle measurements using reformatted computerized tomography scans

STUDY DESIGN

Survey of intraobserver and interobserver measurement variability.

OBJECTIVE

To assess the use of reformatted computerized tomography (CT) images for manual measurement of coronal Cobb angles in idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

Cobb angle measurements in idiopathic scoliosis are traditionally made from standing radiographs, whereas CT is often used for assessment of vertebral rotation. Correlating Cobb angles from standing radiographs with vertebral rotations from supine CT is problematic because the geometry of the spine changes significantly from standing to supine positions, and 2 different imaging methods are involved.

METHODS

We assessed the use of reformatted thoracolumbar CT images for Cobb angle measurement. Preoperative CT of 12 patients with idiopathic scoliosis were used to generate reformatted coronal images. Five observers measured coronal Cobb angles on 3 occasions from each of the images. Intraobserver and interobserver variability associated with Cobb measurement from reformatted CT scans was assessed and compared with previous studies of measurement variability using plain radiographs.

RESULTS

For major curves, 95% confidence intervals for intraobserver and interobserver variability were +/-6.6 degrees and +/-7.7 degrees, respectively. For minor curves, the intervals were +/-7.5 degrees and +/-8.2 degrees, respectively. Intraobserver and interobserver technical error of measurement was 2.4 degrees and 2.7 degrees, with reliability coefficients of 88% and 84%, respectively. There was no correlation between measurement variability and curve severity.

CONCLUSIONS

Reformatted CT images may be used for manual measurement of coronal Cobb angles in idiopathic scoliosis with similar variability to manual measurement of plain radiographs.

The vertical expandable prosthetic titanium rib implant for the treatment of thoracic insufficiency syndrome associated with congenital and neuromuscular scoliosis in young children

Expansion thoracoplasty and vertical expandable prosthetic titanium rib (VEPTR; Synthes Spine Co., West Chester, Pennsylvania, USA) implantation is a new method for the treatment of thoracic insufficiency syndrome and congenital spinal deformity in children. The longitudinal rib implant expands the thorax and indirectly corrects spinal deformity, thus allowing spinal, thoracic and probably lung growth. VEPTR has been used since 1989 in San Antonio, USA, and was introduced to Europe in 2002. This paper describes the preliminary experience with the European patients. Fifteen children with progressive scoliosis had a VEPTR implantation at a mean age of 6 years (11 months to 12 years). Nine children had thoracic insufficiency syndrome due to unilateral unsegmented bars (n = 4), absent ribs (n = 1), hemivertebrae (n = 2) or bilateral fused ribs (n = 2). Six children had severe thoracolumbar scoliosis and pelvic obliquity due to neuromuscular scoliosis. After VEPTR implantation, families and patients reported improvement of the thoracic insufficiency syndrome and better sitting abilities in the neuromuscular patients, as well as radical cosmetic improvement. There were three complications (skin breakage, lumbar hook displacement, rib fracture) after performing fifteen primary VEPTR implantations and 13 expansion surgeries in eight patients. Our experience suggests that expansion thoracoplasty and VEPTR implantation is a safe and efficient method for the treatment of thoracic insufficiency syndrome in young children with severe scoliosis.

A new operative classification of idiopathic scoliosis: a peking union medical college method

STUDY DESIGN

A retrospective radiographic study on the type of surgically treated idiopathic scoliosis, with a prospective study on the reliability of the type-related fusion guide.

OBJECTIVES

To identify and classify surgically treated idiopathic scoliosis, and define its related fusion levels by a new classification system.

SUMMARY OF BACKGROUND DATA

Some classification methods for idiopathic scoliosis have been suggested. However, poor intraobserver reproducibility and interobserver reliability were experienced in these studies, and were not appropriate for guiding surgical planning.

METHODS

A total of 427 surgically treated idiopathic scoliosis cases were reviewed. Preoperative and postoperative standing anteroposterior, lateral, and preoperative supine side-bending radiograph were analyzed using the Scoliosis Research Society definition of scoliosis and curve apex. The resulting classification was tested for intraobserver reliability and interobserver reliability, and by 6 surgeons. Apical frequencies were determined for each type, and prospective surgical testing of the new type and its related fusion guide was performed.

RESULTS

Three major types and 13 subtypes were identified, of which the Peking Union Medical College type I accounted for 56.62%, type II 42.16%, and type III 1.22%. The interobserver reliability testing was 85% (kappa coefficient 0.832), while intraobserver reproducibility was 91% (kappa coefficient 0.898). Each type had its corresponding fusion levels. A prospective study of 152 cases was performed according to the classification. All of these cases were followed over 18 months, and no postoperative decompensation was noted.

CONCLUSION

The Peking Union Medical College classification of idiopathic scoliosis is one system to combine each type with its corresponding fusion level, and it had much higher interobserver reliability and intraobserver reproducibility than the King system. Further prospectivestudies would help to clarify and expand this system.