Preliminary exploration of using ultrasound to quantitatively evaluate the development of epiphyseal cartilage and analyze its correlation with bone age, based on the ultrasound findings of the long bone joint end.

A study was conducted on adolescents studying at a sports school in Jining from March to June 2023. Age, height and other information were recorded. Bone age assessment by X ray were performed within 1 week with an endocrinologist interpreted the bone age using the Greulich-Pyle atlas. Two sonographers scanned a total of 7 sites in the hand, wrist and knee joint of the non-dominant side (including the dorsal side of the third metacarpal head, the ulnar styloid process, the radial styloid process, the medial and the lateral femoral epicondyle, dorsal tibia, and medial tibial condyle). The ultrasonic epiphyseal cartilage thickness (UECT) was measured and its correlation with bone age was analyzed. Intraclass correlation coefficient (ICC) was used to evaluate the reliability and repeatability of UECT measurement.

A total of 141 adolescents were included, with 80 males and 61 females. The average age was 13 (12-14) years old. The average bone age was 15(13-17) years in males and 16 (14-17) years in females. The proportion of the males and females whose bone age was 1 year older than chronological age was 60% and 67%, respectively, and the height of the males was significantly higher than that of the females(P < 0.001). The UECT of 7 sites in the males and females decreased with the increase of bone age, and there was a significant negative correlation between UECT and bone age. In males, UECT was highly and negatively correlated with bone age (|r|≥0.80), while in females, it was moderately and negatively correlated (0.65≤|r|≤0.75). The correlation between the sum of UECT at seven sites and bone age reached high levels in both sexes(|r|=0.93, |r|=0.80).When 3 sites of hand and wrist or 4 sites of knee joint were selected separately, the UECT of the females was highly negatively correlated with bone age (|r| ≥0.76), while that of the males showed a very high correlation (|r| ≥0.90). The measurement consistency of UECT in all seven sites was good (ICC≥0.75).

Ultrasound can observe and describe the developmental change of long bone, and UECT has potential value in quantitative evaluation of bone maturity.