Abstract:   Objective    To provide basic reference for the formulation of photographic positions in line with the characteristics of sacral development of minors, optimization of sacral X-ray images and diagnosis of diseases by investigating the change rules of sacral morphology parameters and pubic symphysis position of minors aged 0~18 years in different age groups and genders.   Methods   The collected total abdominal CT scans from 0 to 18 years old were divided into 3 age groups according to age: 0 to 6 years old, 7 to 12 years old, and 13 to 18 years old. The data was imported by mimics 21.0 and 3D digital image reconstruction technology was used to analyze sacral slope (SS), sacral 1-2 inclination Angle (S1~2T), sacral kyphosis Angle (sacral kyphosis, SK), S2 anterior margin and Sacro4 caudal-1 tilt line Angle (α Angle), S1 upper endplate and S2 anterior margin Angle (β Angle), S4Co1 oblique line and S1 upper endplate Angle (θ Angle), the line between the pubic union and the lower margin of the sacrum and the Angle between the vertical line of the long axis of the body (Angle B).  The parameters in different genders and ages were compared.    Results    Angle B of sacral morphometry was greater in females than in males, and there was no significant difference in other parameters. There were significant differences in SS, SK, α, β, θ between 0~6 years old and 13~18 years old, and between 7~12 years old and 13~18 years old, but no significant differences in other age groups.    Conclusions    There was no gender difference in sacral morphology during the growth and development of juveniles. The Angle between the lower sacral margin and the superior symphysis of pubis is greater in juvenile females than in males. With the increasing of age, the degree of sacral tilt increased gradually, the degree of lower sacral tilt decreased. In order to obtain a clearer image of the sacrum the X-ray incidence Angle should be adjusted according to gender, age, and examination purpose.

Key words: Minors; ,  , Sacral morphology; ,  , Pubic symphysis; ,  , Three-dimensional digital measurement