| Objective:To provide evidence for the treatment of unstable pelvic fractures in adolescents aged10-17 years,digital analysis and measurement of the sacral safe bone screw paths in adolescents were conducted and the regularity of the changes in the screw paths with age was observed.Methods:A total of 160 healthy adolescent volunteers aged 10-17 years old from the Affiliated Hospital of Inner Mongolia Medical University from May 2012 to May 2020 were collected as research objects,there were 80 male volunteers and 80 female volunteers,they were divided into eight age groups,each age group consists of 20 people,there were 10 men and 10 women in each group,all data were randomly selected,samples were normally distributed,no tumor,bone deformity,and CT scan images were clear.Through continuous spiral CT scanning of the abdomen,the pelvis was reconstructed on the three-dimensional surface of the obtained data.Multi-layer subsections were performed on the transverse sacrum and the axial anatomical plane of the pedicles of the 1st and 2nd sacral vertebrae(the pedicles were bilateral)with 1.0mm spacing,and the geometric boundaries of the safe areas of the 1st and2 nd sacral vertebrae were determined on the subdivision plane of each layer,and the two-dimensional image coordinates of the geometric boundary points were extracted.The maximum tangent circle of the boundary is fitted,and the coordinates of the center of the tangent circle are obtained.Then,the least square method is used to fit a straight line in space closest to each center point,which is regarded as the central axis of the geometrically optimal screw path.Along this central axis,the optimal screw path is generated.The width of the axial "narrow point" of the optimal placement channel of sacral 1 and sacral 2 transverse sacroiliac screws was measured bilaterally,and the length of sacral transiliac screw channel(trans-sacral trans-iliac,TSTI)was measured.At the same time,the long and short axis length of sacral 1and sacral 2 sacral projection through iliac channel was measured,and the changes of the channel with age were observed.The data were analyzed and processed by SPSS 18.0statistical software.Results:The range of safe passage width of sacral 1 sacroiliac screw(male: left 8.96 ±2.02 mm,right 9.03 ±2.24mm;female: left 8.26 ±1.96 mm,right 8.37 ±2.11mm),sacral 2 sacroiliac screw width(male: left 6.49 ±1.98 mm,right 6.38 ±1.88mm;female: left 6.21 ±1.76 mm,right6.14 ±1.55mm).The results showed that there was no significant difference in the width of sacral safe passage through ilium between left and right sides of sacral bone of the same sex(P > 0.05).The range of sacral transiliac screw length in sacral 1(male 141.25 ±5.92 mm,female 134.37 ±5.68mm)and sacral 2 sacral transiliac screw length(male 126.28 ±4.94 mm,female 122.31 ±5.13mm).According to the analysis,there was a significant difference in the length of sacral safe passage through ilium between male and female(P < 0.05).The range of long axis length of sacral 1 projection(male 28.27 ±3.17 mm,female 22.36 ±2.73mm),minor axis length(male 13.51 ±1.67 mm,female 9.85 ±1.34mm),sacral 2 projection long axis length(male 19.75 ±2.44 mm,female 16.15 ±2.28mm),minor axis length(male 12.96 ±1.24 mm,female 9.33 ±1.16mm).The length of major and minor axis of sacral 1 and 2 sacral bone projection through iliac channel changed with age.Conclusions:There is a safe bony iliosacral screw channel in both sacral 1 and sacral 2 in adolescent.with the increase of age,the proportion of long and short axis of sacral projection through the safe area of iliac channel increases gradually,and the growth rate of projection area height is faster than that of width.In adolescents with normal sacral anatomy,unstable pelvic fractures can be fixed with sacral 1 or sacral 2 screws,but factors such as the length of the screw and the gender of the patient need to be considered. |
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