Preliminary study on ultrasound-based quantitative assessment of epiphyseal ossification angle for bone age evaluation in children

Background: Bone age (BA) assessment is crucial for evaluating pediatric growth, yet the standard radiographic method involves ionizing radiation. This study aimed to investigate the feasibility of a novel, quantitative ultrasound parameter-the epiphyseal ossification angle (OA)-as a non-invasive alternative for BA evaluation, and to examine its correlation with radiographically determined BA. Methods: In this prospective study, 201 Chinese Han girls aged 5-14 years (mean age: 9.24±2.15 years) underwent both left wrist radiography and ultrasonography of the distal radius, distal ulna, and medial femoral condyle within a 1-week interval. The OA and the established ossification ratio (OR) were measured at each site. Composite indices-the total ossification angle (TOA, sum of OAs) and skeletal maturity score (SMS, sum of ORs)-were calculated. Radiographic BA was determined by the Tanner-Whitehouse 3 (TW3) method as the reference standard. Reproducibility was assessed using intraclass correlation coefficients (ICC), and correlations were analyzed with Pearson's method. Results: =0.653, P