Radiation-free Assessment of Scoliosis: A Reliability and Validity Study for Ultrasound Angles

Study designA prospective study.ObjectivesThis study aimed to evaluate the reliability and validity of ultrasound angles, and to explore the impact of body mass index (BMI) and scoliosis status on the accuracy of ultrasound measurements.MethodsA total of 94 subjects were enrolled in this study and subsequently underwent both X-ray and ultrasound examinations. Two orthopedic surgeons independently measured the radiographic Cobb angle and the ultrasound angle to evaluate the intra- and interobserver reliability of ultrasound angles. Based on apical vertebra location, BMI, and scoliosis status, subjects were stratified into clinically relevant subgroups. Linear regression analyses and Bland-Altman plots were employed to assess the accuracy of the ultrasound measurements.ResultsUltrasound angles demonstrated excellent intra- and interobserver reliability (intraclass correlation coefficients, ICCs ranging from 0.939 to 0.99), and manual ultrasound angle showed better correlation with the radiographic Cobb angle than the automatic ultrasound angle. The lowest R² of 0.425 was observed for the automatic ultrasound angle in the overweight group, while manual ultrasound angle maintained comparable correlation with the Cobb angle across different BMI subgroups. Furthermore, a higher correlation was found between ultrasound angles and the Cobb angle in the scoliosis group compared to the non-scoliosis group.ConclusionsThis study showed that ultrasound angles were reliable and valid. Manual measurements showed superior performance and should be prioritized. When using ultrasound angles to assess spinal curvature severity, the influence of BMI and scoliosis status must be considered.