Abstract: Objective  To study the changes of occipitocervical Angle (OC2A) and posterior occipitocervical Angle (POCA) in children and adolescents with age and gender, so as to provide theoretical basis for the clinical treatment of occipitocervical fusion.    Methods    The imaging data of 321 cases (213 males and 108 females) were retrospectively studied and divided into 6 groups according to sex and age, including 1~3 year-old group, 4~6 year-old group, 7~9 year-old group, 10~12 year-old group, 13~15 year-old group and 16~18 year-old group. The original cervical tomography data were stored in DICOM format and imported into Mimics 16.0 to analyze the OC2A and POCA.   Results   By analyzing OC2A and POCA in different age groups, it was found that the peak values of OC2A and POCA were (18.15±5.63) ° and (124.94±14.63) °, respectively in the 10-12 year-old group, and then showed a wavy downward trend. There were significant differences in OC2A between 10-12 year-old and 1-3 year-old and between 13-15 year-old and 10-12 year-old (P<0.05). There were  significant differences in POCA between the 7-9 year-old group and the 10-12 year old group, the 13-15 year old group and the 16~18 year old group (P<0.05). There was no gender difference in OC2A and POCA between males and females (P>0.05). In correlation analysis, there was a negative correlation between OC2A and POCA (r =-0.28, P=0.000).    Conclusions    In the clinical treatment of occipitocervical fusion, only age differences can be considered, without considering gender differences. This study, through the systematic study of occipitocervical Angle and posterior occipitocervical Angle in children and adolescents, also provides theoretical basis for the Angle selection of OC2A and POCA in posterior occipitocervical fusion.

Key words:  Occipitocervical angle; ,  Posterior occipitocervical angle; ,  Correlation; ,  Occipitocervical fusion; ,  , Children; ,  , Adolescents