Interobserver Agreement Between Orthopedic Surgeons and Radiologists in Cobb Angle Measurement on Plain Radiographs in Patients with Scoliosis

Abstract

Objective: The aim of this study is to evaluate interobserver agreement in Cobb angle measurements on plain radiographs of patients with scoliosis and to compare measurement consistency between orthopedic surgeons and radiologists, as well as across different levels of experience and gender groups.Materials and Methods: In the study, 55 physicians (specialists and residents) independently performed measurements on three anonymized scoliosis radiographs representing different curve severities using the standard Cobb method. A total of 165 measurements were obtained. Statistical analyses were conducted using IBM SPSS Statistics 31 software. Interobserver agreement was evaluated using the Intraclass Correlation Coefficient (ICC), and internal consistency was assessed using Cronbach’s alpha coefficient. A two-way random-effects model and a consistency approach were applied in the analyses, and the level of significance was set at p0.05). Overall internal consistency was low, with a Cronbach’s alpha value of 0.301. The ICC value for single measurements was 0.126 (95% CI: -0.094–0.569), and the ICC value for average measurements was 0.301, indicating weak interobserver agreement. Weak positive correlations were identified between measurements obtained from different cases.Conclusion: Interobserver agreement in Cobb angle measurements was found to be low. Measurement variability may arise not only from observer-related factors but also from inherent limitations of the method. These findings emphasize the need for standardized measurement protocols in clinical practice and suggest that digital tools and artificial intelligence–assisted methods may improve measurement reliability.