Cobb Angle Measurement of Scoliosis Using Computer Measurement of Digitally Acquired Radiographs-Intraobserver and Interobserver Variability

Abstract

Study DesignWe evaluated computer assisted digital measurement of radiographic parameters in patients with idiopathic scoliosis.PurposeTo assess the reliability of digital measurements.Overview of LiteratureVarious authors analyzed scoliotic deformities by conventional radiographs, but very few studies have addressed the reliability of digital radiographic measurement using computer software.MethodsThree independent, blinded observers measured 318 whole spine pre-operative antero-posterior radiograms of children with varying degrees of idiopathic scoliosis. Only one curve per radiograph was measured. Each observer measured the Cobb angle three times with a 1-week gap between each measurement. The computer system, picture archiving and communication system (PACS, PiViewSTAR version 5) was used in all cases. The end vertebrae were pre-selected to avoid this as a potential source of error. The results were statistically analyzed for intraobserver and interobserver reliability and variability.ResultsThe 95% confidence intervals for intraobserver and interobserver variability were ±1.30 and ±1.260, respectively. There was better reliability in larger curves.ConclusionsMeasurement using a digitized system may help to minimize measurement discrepancies by eliminating an intrinsic cause of error.

Measuring procedures to determine the Cobb angle in idiopathic scoliosis: a systematic review

“…It might be of more use to ascertain in a study the reliability and agreement of the new procedure alone and then compare these results to those of the reference test. This was not done or the data were not presented in a few of the available studies [6][7][8]12].…”

“…Aside from the manual procedure, there are so-called digital computer-assisted (semi-automatic) [6][7][8][9][10][11][12], automatic [13,14] and smartphone app procedures [15,16].…”

Applicability of the Cobb Angle Measurement in Idiopathic Scoliosis Using Scanned Imaging

“…16 In view of this new reality, it became necessary to prove that the new technology available provides information with the same safety and consistency as conventional radiographs. 6 There are articles in the literature that demonstrate good intraobserver and interobserver reproducibility using digital radiographs to measure Cobb angles, 8,14,17 however, most of them use predefined end vertebrae in their methodology.…”

“…12 Despite the higher cost for the initial deployment of digital technology, after one year of use, the savings in printed film begins to pay back. 13 Additionally, digital radiographs offer several features: software with tools to improve the quality of the images and the measurement of angles, distances, and other parameters; 14 viewing and rapid sending by means of e-mail or cellular telephones; 15 easy storage, eliminating the need to print film and saving space; and less exposure to radiation. 12 With the possibility of manipulating the images after they are obtained, there is less need to redo exams because of poor quality.…”

Spinal fusion surgery: A historical perspective

“…The Cobb classification is an efficient way for surgeons to understand the extent of deformity, monitor changes in curvature, and classify different types of curves. 17 In 1946, Dr. Walker Blount and Dr. Albert Schmidt developed the ''Milwaukee Brace'' to minimize progression of scoliosis to an acceptable level and to immobilize patients after surgery. This brace is still in use today.…”