[Relationship between hand and wrist bone age assessment method and application to male children]

Objective: To explore the interrelationship among three simplified hand and wrist bone age assessment methods and to establish corresponding bone ages for each substage in male children. Methods: This retrospective case series study included 169 left hand and wrist X-rays from 152 male children who underwent bone age assessments at the Pediatric Orthopedics and Pediatrics Departments,Beijing Jishuitan Hospital,Capital Medical University from January 2019 to December 2023. The age at the time of X-ray was (13.7±2.0) years (range:9.1 to 17.9 years). Reasons for bone age assessment included evaluating the progress of adolescent idiopathic scoliosis in 36 cases, predicting limb length discrepancies in 28 cases, and predicting the height of healthy adolescents in 88 cases. Bone age was first graded using the Chinese hand-wrist bone age assessment method. Three simplified hand and wrist bone age assessment methods were then applied:Sanders simplified skeletal maturity staging system(Sanders stage), the distal radius and ulna classification (DRU), and e thumb ossification composite index (TOCI). Somers'delta correlation test was used to analyze the relationship among the results of the three simplified methods. The bone age and standard deviation for each sub-stage were calculated, and gender differences in bone age for the same sub-stage were compared with previous study. Results: The DRU, TOCI and Sanders stages showed a strong correlation when assessing bone age in male children, with Somers'delta correlation coefficients ranging from 0.881 to 0.876 (all P<0.01). The sub-stages with the smallest standard deviations (shorter duration) in each of the three classifications can serve as a quick reference for determining precise bone age, included proximal thumb epiphysis covered, without sesamoid (12.0 years);proximal thumb epiphysis covered with sesamoid or distal radial covered (13.0 years), early capping of the thumb epiphysis, radial epiphysis medial side capping(13.5 years), all phalangeal epiphyses capping (14.0 years), distal phalangeal physes beginning to close (14.5 years), all distal phalangeal physes closed (15.0 years), middle or proximal phalangeal physes beginning to close (15.5 years), all digital epiphyses closed (16.5 years), and nearly complete distal radius fusion with a notch (17.5 years). On average, the bone ages of males were 2 years behind those of females in the same substage. Conclusions: The DRU, TOCI, and Sanders stages can be applied to male children, and it is showed good correlation between them. The subtypes with shorter duration can be used as a quick assessment method to determine the bone age.