The Digital Developmental Anatomic Study Of Cervical Joint Cartilage In Children Aged 1～6 Years

Objective:1.To study the growth characteristics of atlantoaxial articular cartilage in normal children aged 1～6 years,and to explore the closing age,anatomical indexes,developmental characteristics and the rule of changes with age of the cartilage structure,so as to analyze the influence of atlantoaxial articular cartilage on atlantoaxial articulation in children.2.The anatomical and location anatomical indexes of cervical central articular chondrosis in normal children aged 1～6 years were studied to analyze the trend and developmental difference of the ossification of cervical central articular chondrosis in different cervical segments and the developmental process characteristics of the central articular chondrosis with age changes in the same age group.The influence of the central articular chondrosis of the cervical spine was analyzed from the two aspects.To investigate the characteristics of the anatomical indexes of the cervical spinal cartilaginous union and the effects of various ossification modes on the maintenance of the normal anatomical structure of the cervical spine.Methods:160 cases of normal cervical spine CT imaging data of children aged 1～6 years were collected and divided into 6 groups according to 1-year-old age group,20 cases in each group,20 cases in each group,20 cases in each group,and 30 cases in each of the other 4 groups.In this study,20 cases in each age group were divided into 20 cases in each age group,as the anterior interarch and posterior interarch cartilage existed only in 1～4 years old and were relatively small in quantity.The original cervical spine tomography data from continuous CT scans were imported into Mimics16.0 software in DICOM format for measurement.The morphological and anatomical indicators of the cervical joint cartilage were measured on the coronal plane and cross section,respectively,under the two-dimensional image window and the Measurements toolbar.The measurement indexes were divided into self indexes and position indexes of each joint cartilage.Results:1.The anterior and posterior interarch cartilages closed at about 4-year-old.In the image data of children aged 1～2 years old,both the anterior and posterior interarch cartilages existed.However,in the data of children aged 3～4 years,the presence rate decreased gradually.2.All the joint cartilages of C₂～C₇ cervical vertebrae closed at about 6～7 years of age.3.Anatomical structure development characteristics of atlanto-axial region associated cartilage:（1）Transverse diameter,sagittal diameter,height,area and circumference of anterior interarch atlanto-anterior cartilage decreased gradually with age,and the decrease was the largest at 1～2years old.Transverse diameter,sagittal diameter,height and area of 1-year-old and 2-year-old groups had statistical differences compared with that of 4-year-old group（P<0.05）.（2）The transverse diameter,area and circumference of the lateral intermass cartilage of the anterior atlas arch decreased gradually with age,and the sagittal diameter increased gradually from 1 to5 years old.（3）The transverse diameter,area and circumference of the posterior interarch of the atlas decreased with age,and the decrease was greatest between the 1-year-old group and the2-year-old group.The transverse diameter,area and circumference of 2～3 years old group were significantly different from those of 4 to 4-year-old group（P<0.05）.（4）The transverse diameter and area of the lateral intermass cartilage of the axial anterior arch decreased with age.The circumference of sagittal diameter increased with the increase of 1-year-old to 4-year-old group,and decreased gradually with the increase of 5-year-old to 6-year-old group.4.Anatomical characteristics of the location and development of the atlantoaxial articular cartilage:（1）The distance between the lateral masses of the anterior arch of the atlas increased with age,and the Angle of transverse cartilage formation on both sides decreased with age.（2）The transverse Angle of the armature odontoid interarch cartilage decreased with age,and the coronal Angle increased with age.Meanwhile,the distance from the transverse process,the distance from the odontoid tip and the distance between the two sides of the cartilage increased with age.5.Anatomical characteristics of the central chondrosis of C₂～C₇ cervical spine segments:（1）The transverse diameter and circumference of the central chondrosis of C₂～C₇ cervical spine segments decreased gradually with age,with the maximum area in the 2-year-old group and the maximum reduction in the 3-5 years old group.The sagittal diameter and circumference were slightly increased.The transverse diameter of C₂～C₇ in 1-year-old group was significantly different from that in 4-year-old group,5-year-old group and 6-year-old group（P<0.05）.（2）In the same age group,along with the cervical spine descending,the central cartilage of the nerve arch combined with anatomical indicators mostly have a larger value in the middle cervical segment.6.Anatomical structure development characteristics of the central cartilaginous association of the nerve arch of C₂～C₇ cervical vertebra:（1）The central cartilaginous association of the nerve arch of C₂～C₇ cervical vertebra gradually grows in the direction of the lateral vertebral arch with age,and the distance between the lateral cartilages gradually increases,along with the gradual reduction of the Angle between the lateral cartilage and the horizontal plane on the cross section,and the Angle between the transverse section and the vertebral body.The distance from the transverse process gradually increased,and the degree of cartilage ossification was found to be slower than that of vertebrae.The distance between the central cartilaginal junction of the C₂～C₅ nerve arch on both sides of the 4-year-old group,the5-year-old group and the 6-year-old group were statistically different from the 1-year-old group and the 2-year-old group,respectively（P<0.05）.（2）In the same age group,with the descending of the cervical spine,the central chondrosyndesis of the bilateral neural arch gradually grew to the direction of the bilateral vertebral arch,and most of them had a large range of changes in C₇.7.Correlation analysis of each index showed that there was a high correlation between transverse diameter and area,and between area and circumference of the central chondrochondrosis of the C₂～C₇ neural arch.There is a high correlation between the transverse Angle of C₂～C₇ central articular junction and the horizontal Angle.8.Multiple linear regression analysis showed that the transverse diameter of the central articular cartilage of the nerve arch was affected by age and area;The distance between bilateral cartilages is affected by age.Conclusions:1.Anterior and posterior atlanto-interarch cartilage mostly appear at 1～4years of age and close at 4～5 years of age.With the increase of age,the anatomical indexes gradually decrease,and the ossification process is relatively stable.2.The cartilage between lateral mass of anterior arch of atlas and interarch of axial odontoid closed at about 6～7 years of age,and the anatomical indexes gradually decreased with the increase of age,and ossified toward the lateral mass arch of both sides.3.There were significant differences in the central cartilaginous anatomical indexes of C₂～C₇ segments of the cervical spine.With the increase of age,the degree of ossification increased,and the anatomical indexes of cartilage showed a decreasing trend.As the cervical spine descends,the cartilaginous ossification process in the middle cervical region is later than that at the upper and lower ends.4.The central cartilaginous association of the neural arch gradually grows to both sides of the vertebral arch.As the vertebral body descends,it also gradually grows to both sides of the vertebral arch,suggesting that it mainly promotes the growth of the vertebral arch in vertebrae.