| Objective To investigate the children aged 4 to 12 pedicle morphology and development law, provide the basic theory basis for the feasibility of screw insertion, screw design and related biomechanical study; To discuss the feasibility and accuracy of transpedicular screw placement assisted by the individualized navigation templates in cadaveric children cervical spines. Method 1. Selected the non-cervical spine trauma and deformity of the children aged 4 to 12 of 60 cases of cervical CT scan data, to importe three-dimensional reconstruction software Mimics as DICOM format and measure the parameters of pedicles of 3D model, then to statistically analyze by age group and segments. 2. 4 children cadavers were randomly divided into 2 groups .One group firstly imitated screw placement in the three-dimensional reconstruction and related parameters was measured,then with the measure results implanted pedicle screw by bare-handed method;the other group based on their CT scan data, using computer-aided design and rapid prototyping technology designed the corresponding individual navigation template of cervical pedicle screw placement, implanted pedicle screw by this template. Each group implanted 28 pieces screws .Observed by CT scan and comparison the accuracy and quality of two methods to statistical analysis. Results: 1.PW, PH, TLand e angle increased gradually with age, f angle changes a little but in different cervical spine angle changes larger. I value of C1 changes with age no significant differences ,and all more than 1.0; I values of C2 changes in all age groups no difference, and all less than 1.0; I value of C3 C7 changes in each age group from the more than 1.0 to less than1.0. C1, C2 and C3 7 pedicle have different characteristics. 2. The bare-handed group （D group） were inserted 28 screws, in which the optimal grade 11 （39.3%）, the fine grade 10 pieces （35.7%） and the poor grade 7 pieces （25.0%）; the navigation template group （E group） were also placed 28 pieces screws, in which the optimal grade 19 pieces （67.9%）, the fine grade 6 pieces （21.4%） and poor grade 3 pieces （10.7%）. The two groups did not differ between the success rate of pedicle screws （P> 0.05）, but the optimal grade rote in screws placed were different （P <0.05）, E group more than D group. Conclusion 1. By digital three-dimensional reconstruction techniques in children aged 4 to 12 were observed cervical spine, pedicle angle of the line and the overall diameter increased gradually with age. Cervical pedicle different segments with different characteristics, its development has a certain regularity, children over 4 years on the morphology of the cervical pedicle have the feasibility with a minimum 3.5mm diameter screws to inserte.2.Using Mimics software simulation of pedicle screw placement in three-dimensional reconstruction and measurement parameters, applicate to clinical ,it can guide screw placement, and increase the success rate of screw placement, but it need certain degree of technical experience accumulation. 3. The method of children cervical pedicle screw placement assisted by individual navigation template has a good success rate, it’s simple, easy to master, fully embodies the individual principle . |
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