Measuring the cobb angle one of the most common angle used in the measure of scoliosis progression is the cobb angle. Results the computerbased algorithm calculated cobb angles within 5 degrees of orthopedic surgeons average with a standard deviation of 3. Some studies say that the patient does not require any specific treatment, but just needs regular checkups to see if the curve is progressing until bone. Is regarded as a minimum angulation to define scoliosis. The cobb angle helps a doctor to determine what type of treatment is necessary.
The measurement of the cobb angle is an important basis for selecting therapeutic methods and evaluating therapeutic effects. Pdf cobb angle measurement of spine from xray images. To measure the cobb angle, one must first decide which vertebrae are the endvertebrae of the curve deformity the vertebra whose endplates are most tilted towards each other lines are then drawn along the endplates, and the angle between the two lines, where they intersect, measured. To measure and calculate the scoliosis cobb angle by end vertebra tilt angle method tilt angle method and assess its accuracy and usability. Variation in cobb angle measurements in scoliosis springerlink. In other words, a 40 degree cobb angle is more than twice as severe as a 20 degree cobb angle. In such a situation computerized cobb angle measurement becomes an effective tool for scoliosis evaluation and reducing the variability of cobb angle measurement. Reliability assessment of cobb angle measurements using manual and digital methods. The accuracy of cobb angle measurement on ct scan projection. To measure the cobb angle, one must first decide which vertebrae are the endvertebrae of the curve deformity the vertebra whose endplates are most tilted towards each other. These measurements are generally reliable and accurate 11. The cobb angle is best understood within the context of the individual patient.
In order to determine the reliability of the cobb angle measurement as it is used in the clinical management of scoliosis, a methodological survey was carried out. A cobb angle in the range of 10 to 20 degrees is considered as mild scoliosis. The easyangle performs the functions of the goniometer, inclinometer. Cobb suggested that the angle of curvature be measured by drawing lines parallel to the upper border of the upper vertebral body and the lower border of the lowest vertebra of the structural curve, then erecting perpendiculars from these lines to cross each other, the angle between these perpendiculars being the angle of curvature. The cobb angle is used as a standard measurement to determine and track the. The measurement of cobb angle involves estimating the angle between the two tangents of the upper and lower endplates of the upper and lower end vertebra, respectively, as shown in figure 3. University of groningen automatic cobb angle determination. Ethical approval for cobb angle evaluation was obtained because volunteers would be used to make cobb angle measurements on the images.
Measurement of scoliosis cobb angle by end vertebra tilt. Besides absolute cobb angle measurements, a worsening of physiologic vitality despite a static neurologic condition can be a signal to entertain surgical stabilization. Use of the iphone for cobb angle measurement in scoliosis. Cobb angle measurement of spine from xray images using convolutional neural network article pdf available in computational and mathematical methods in medicine 20199. The cobb angle is used to measure the curvature of the spine. The angle can inform doctors of the severity of scoliosis, whether the condition is progressing, andor whether treatment is working. Measurement of scoliosis cobb angle by end vertebra tilt angle. John r cobb where he outlined how to measure the angle of the spinal curve. The cobb angle of a scoliotic curve is the angle formed by the intersection of two lines, one parallel to the endplate of the superior end vertebra and the other parallel to the endplate of the inferior end vertebra fig 3a.
Determining the cobb ray plate involves selection of the extreme. Variation in cobb angle measurements in scoliosis, volume 23, number 7 october, 1994 reliability of the cobb angle index derived by traditional and computer assisted methods. Over the last several decades, the cobb measurement performed on radiographs has been the most universally used method to characterize a spinal deformity. Although the calculation of scoliosis cobb angle is a simple technique, there has been considerable interobserver variability 6.
However, the cobb measurement does not describe all of the important characteristics of a spinal deformity. Reliability assessment of cobb angle measurements using. New pacs systems do allow for easier cobb angle measurements without the use of goniometers. Pdf cobb angle measurement of scoliosis with reduced variability. A cobb angle describes the maximum distance from straight a scoliotic curve may be. This result was based on a 95% confidence interval with p values cobb angle is the most widely used measurement to quantify the magnitude of spinal deformities, especially in the case of scoliosis, on plain radiographs. Due to the threedimensional rotation of the spine, cobb angles measurements made on a twodimensional xray do not represent an increase in the severity of the scoliosis in a uniform fashion.
The highest range of manual cobb measurements on any lm has been reported as 8 degrees 6. Cobb angle measurement of scoliosis with reduced variability raka kundu, amlan chakrabarti. The manual line drawing and artificial observation are still the main reasons for measuring error. This article is published with open access at abstract. Two examiners were respectively asked to measure the. The overall performance of the automatic cobb angle calculation method was quite satisfying, since the automatic measurement never declined more than 5o from the manual one. It is used as the standard measurement to quantify and track the progression of scoliosis. Digital cobb angle measurements obtained by using a software figure 2. Scoliosis is a common deformity, and its severity is usually assessed by measuring the cobb angle on the spinal xray film. The cobb angle is also the preferred method of measuring posttraumatic kyphosis in a recent metaanalysis of traumatic spine fracture classifications. Variability in cobb angle measurements using reformatted computed tomography scans. Exceptions include measuring kyphosis in the upper thoracic spine and measuring cobb angles in large curvatures because of difficulty in precisely defining the endplates. Cobb angles may also be used to describe kyphotic and lordotic angulation on the lateral view.
Pdf use of the iphone for cobb angle measurement in scoliosis. Digital goniometer scoliosis how to measure the cobb angle. The standard deviation of the differences in cobb angle for the repeated radiographs amounted to 3. While the cobb angle is the current standard for scoliosis measurement, its important to recognize three significant points. Scoliosis is defined as a lateral spinal curvature with a cobb angle of 10 4.
After the 18 images had been acquired, they were inspected visually, using a grading scale, to identify which images were of suitable quality for cobb angle measurements to be performed. Cobb angle is a measurement of the degree of sidetoside spinal curvature, which is a deformity you may know as scoliosis. Cobb angle used to measure scoliosis curves spinehealth. A novel algorithm article pdf available in international journal of spine surgery 1. Measurement of the cobb angle on radiographs of patients who. The manual method was measured by an orthopedic surgeon specialized in scoliosis. Pulmonary function may slip away progressively even with a stable neurologic underpinning. Cobb angle and scoliosis core concepts physiotherapy. Cobb angle measurement of spine from xray images using. Cobb angle is used worldwide to measure and quantify the magnitude of spinal deformities, especially in the case of scoliosis.
In cases where the curvature is not marked, then the lines will not intersect on the filmmonitor, in. Scoliosis severity is moderate when the cobb angle ranges from 20 to 40 degrees. In respect of the first phase, the variation in production of the radiographs was calculated on cobb angle measurements made by one investigator on serial radiographs of patients who underwent spinal fusion for scoliosis and therefore had a fixed spinal curvature. Generally, it takes at least 10 degrees of deviation from straight before scoliosis is defined. Feb 20, 2019 in this easyangle measurement video, we demonstrate how to measure the cobb angle using the easyangle digital goniometer. Computerassisted cobb angle measurement from posteroanterior. Comparison of two and threedimensional measurement of the.
Pdf measurement of scoliosis cobb angle by end vertebra tilt. Jun 30, 2017 cobb angles measured by the surgeons were averaged and compared to measurements of the same angle by the computerassisted method using linear regression and the methodology of bland and altman which is useful for comparing two methods of measurement. Spinal deformity study group radiographic editors in chief. It is deduced that the cobb angle is the sum of upper and lower end vertebra tilt angles through the law of plane geometry. Several computerized cobb angle measurement techniques have been developed to improve the reliability and accuracy of measurement method till date. Here is a general outline of cobb angle ranges and what they could indicate in idiopathic scoliosis found in children and adolescents. Curves that are less than 10 degrees are not considered to represent scoliosis, but rather a minor spinal asymmetry. Nov 10, 2017 the cobb angle is important in measuring the degree of scoliosis in the coronal plane, frcs orth revision.
Computerbased methods have been developed for the precise measurement of the cobb angle 4,810. In the measurement of a cobb angle two phases can be distinguished. In respect of the first phase, the variation in production of the radiographs. The cobb angle is the measure the frontal deformation looking from the back to the front or technically, it measures the deformation of the spine at the coronal plane on the anteriorposterior plane. The adolescent idiopathic scoliosis ais is a spine deformity that. The mean absolute difference between pairs of smartphoneprotractor measurements was 2. Reducing a 60 degree scoliosis by 10 degrees represents a. Cobb angle, which is a measure of spinal curvature, is the standard method for quantifying the magnitude of scoliosis, related to spinal deformity in orthopedics. Two more lines are drawn at an angle of 90 degrees to these lines, perpendicular so that they intersect. Cobb angles are preferably measured while standing, since laying down decreases cobb angles by around 710. The cobb angle measurement is the gold standard of scoliosis evaluation endorsed by scoliosis research society. Although it was not clearly stated whether the classic cobb measurement method or the analytical cobb.
Grids, guides, and measurements in pdfs, adobe acrobat. To set measuring tool options, select the tool, then rightclick anywhere in the pdf to view the options. A cobb angle greater than 40 degrees denotes severe scoliosis. The resulting angle is measured, and the number is expressed in degrees. Add or change text that appears with the measurement. The condition of a spine is associated with the spinal curve instead of scoliosis when the cobb angle is less than 10 degrees. Zhang 6 proposed a cobb angle computeraided measurement algorithm based on deep neural network, which can automatically estimate the slope of the spine after manually selecting the block of interest in the upper and lower vertebrae, and automatically measure the cobb angle. Pdf cobb angle, which is a measure of spinal curvature is the standard method for quantifying the magnitude of scoliosis related to spinal deformity. Understanding cobb angles and what it means for scoliosis. Manual cobb angle measurement process from x related to spinal deformity in orthopedics. Two examiners were respectively asked to measure the cobb angle on each radiograph by using the developed software twice.
Paper open access automatic measurement algorithm of. Use of the iphone for cobb angle measurement in scoliosis article pdf available in european spine journal 216. The severity definition for scoliosis is determined using the cobb angle as shown in table 1. Although there is a good reproducibility of the cobb angle measurement between different investigators, the variation in production of a spinal radiograph is an important source. Pdf variability in cobb angle measurements in children. The effect of patient positioning during radiographs on the. The cobb angle is the most widely used measurement to quantify the magnitude of spinal deformities, especially in the case of scoliosis, on plain radiographs. Errico, in surgical management of spinal deformities, 2009. A level of improvement for cobb angle measurement is achieved in the proposed. The project included 32 patients with scoliosis who have received treatment in our hospital from june 2011 to july 2016, whose cobb angles were measured at various segments total 50. John r cobb, an american orthopedic surgeon, to measure the angle of spinal curves. The cobb angle is the sum of the angles of the extremevertebrae fig. The radiographic measurement manual rmm describes many of. Pdf cobb angle measurement of spine from xray images using.