Ultrasonographic assessment of pubertal maturation: a reliable and radiation-free model for bone age estimation

Developing methods that minimize radiation exposure in skeletal age assessment for orthodontic planning and growth monitoring in pediatric populations is a priority. This study aimed to evaluate the diagnostic efficacy of ultrasonography as a non-ionizing alternative in bone age estimation and to analyze the correlation between ultrasonographic skeletal maturation and chronological age.

In this cross-sectional study, the left hand-wrist region of 131 individuals aged 8-18 years was evaluated simultaneously using digital radiography and ultrasonography. Skeletal maturation was analyzed based on the epiphysis-diaphysis relationship of the phalanges and radius, the presence of sesamoid bone, and bone age estimation based on the Greulich-Pyle atlas. In addition, the ossification ratios (o/O) of the distal radius and ulna were calculated. Friedman, Wilcoxon signed-rank, McNemar tests, and regression analyses were used to compare the data.

A strong correlation was found between chronological age, ultrasonographic age, and radiographic age. Statistically significant differences were found between ultrasonography and radiography measurements in all middle phalanges (MP2-MP5), the distal phalanx of the fourth finger (DP4), the distal and proximal phalanges of the first finger (DP1, PP1), proximal phalanges of the second finger (PP2) and the radius (p < 0.05). A high correlation (r = 0.862) was observed between the two methods used to detect sesamoid bones. A strong positive correlation (rs ≈ 0.70) was observed between chronological age and ultrasonographic ossification rates; the explanatory power of radius and ulna measurements on age was 54%.

Ultrasonography shows a strong correlation with both chronological and radiographic age and demonstrates high efficacy in detecting sesamoid bones and monitoring ossification rates. Statistically significant differences have been found between radiographic examination and ultrasonography in evaluating the epiphysis-diaphysis relationship of the phalanges.

This research demonstrates that ultrasonography is a reliable, non-ionizing method for skeletal age assessment and shows significant diagnostic consistency across anatomical regions, similar to that of conventional radiography. Furthermore, it supports the clinical utility of ultrasonography as a reliable, radiation-free method and contributes to ongoing efforts to establish standardized, non-invasive assessment methods.