Which Method of the Radiologic Measurements of the Angle of Curvature in Idiopathic Scoliosis is the Most Reliable for an Inexperienced Researcher?

The aim of the examination was to determine which of the three measurement methods Cobb (CB), Ferguson (FR), and Centroid (CN) has the best repeatability and reliability when the measurements are made by inexperienced researchers.

Three researchers (from the student research group) measured the angle of spine curvature on X-rays of the entire spine in standing anteroposterior view in 50 patients with severe idiopathic scoliosis qualified for surgery. Cobb, Ferguson, and Centroid methods were used. One of the researchers repeated all examinations twice at 3-week intervals. The measurements were compared with each other using the intraclass correlation coefficient (ICC) method. Values less than 0.5 are indicative of poor reliability, values between 0.5 and 0.75 indicate moderate reliability, values between 0.75 and 0.9 indicate good reliability and values greater than 0.90 indicate excellent reliability.

The ICC (inter-rater) between the researchers’ measurements was 0.9387 for CB, 0.9169 for FR, and 0.9061 for CR. Whereas the ICC (intra-rater) between measurements taken by a single researcher was 0.9824 for CB, 0.9088 for FR, and 0.9546 for CR.

The above results show that Cobb angle measurement method is the most reliable for measuring the curvature angle of the spine for novice researchers. Although it seems to be difficult to measure, it provides the most repeatable results.