3D Printing Drill Guide Template Assisted Pedicle Screws Placement In Congenital Scoliosis

Objective:To study on 3D printing drill guide template in screw fixation with severe congenital scolisis, evaluate application effects and make comparison of the accuracy rate between guide template group and free-hand technique group.Methods:66 congenital scoliosis patients who have a complete set of pre- and post-operation CTs were selected from in our hospital before Dec. 2015. 8 patients of them with 3 males and 5 females were screened out for the study by random computerized process.Their pre-operative CT data were uploaded, deformed vertebraes and adjacent vertebrals were selected to set up 3D models in the computer, then models and 3D printing drill guide template were printed. Stimulated the surgeon process, 3D printing drill guide templates were applied in screw fixation on the models.Afterwards, conducted the CT scan and evaluated the accuracy of screw insertion,and compare it with free-hand technique group.Results : All of 3D printed drilling templates had a good suitabilityexcept 4 positions which existed serious malformation. 68 screws were implanted for each group respectively, among them,36 screws were implanted into malformed vertebrae, while 32 screws were implanted into adjacent vertebrae(not malformed vertebrae). 66 screws of the template screw-implanting group didn’t break through vertebral pedicle cortex, and only 2 screws broke through vertebral pedicle cortex. And 49 screws of the free-hand technique group didn’t break through vertebral pedicle cortex, and only 19 screws broke through bone cortex. The total accuracy rate of screw insertion for template group was 97.1%, which was obviously higher than that of free-hand technique group group valued 27.1%.36 screws were implanted for each group on malformed vertebrae respectively.21 screws of the free-hand technique group didn’t break through vertebral pedicle cortex, and only 15 screws broke through bone cortex. While 34 screws of the template group didn’t break through vertebral pedicle cortex, and only 2 screws broke through bone cortex. The accuracy rate of screw insertion in malformed vertebrae of template group was 94.4%,which was obviously superior to that of free-hand technique group valued 58.3%.Conclusion:(1) The 3D printed drilling template of this type played an important role in screw insertion for malformed vertebrae in congenital scoliosis surgery, and the accuracy rate of screw fixation with the help of this template was superior to free-hand technique group.(2) The 3D printed drilling template of this type still exists limitation,the malformed vertebrae which impedes the template from forming effective gomphosis with the bone surface should be excluded.