Study on the nailing path of S3 ala-iliac screw in adult spinal pelvis fixation

Abstract

Objective The screw insertion and parameters of S3 ala-iliac screw fixation were introduced by 3D printing spinal pelvis model and computer software-assisted navigation. Methods Determine the nailing space of the S3 segment by 3D printing model and computer software related data, and select the position of the iliac screw into the needle point. Twenty of the male and female adult patients who had undergone three-dimensional pelvic CT reconstruction scans were randomly selected. The screw point O was selected, the horizontal section X was the coronal or sacral horizontal cross-section. Spherical probe into the minimum angle of the needle angle range A, the maximum angle range B and the optimal range of nailing angle Z was measured, and the needle point screwed into the screw pin length and width. The accuracy and safety of this new method of nailing were confirmed in the corresponding adult 3D printing model. Results The needle angle is within the range of the minimum angle OA to the maximum angle OB. If the narrowest diameter is more than 7 mm, the fixation can be safely done with a universal Iliac screw (average length 80-90 mm). The range of needle angle was (47.1±1.9)°-(56.7±1.4)° for the male X-OA-OB plane and (52.3±1.1)° for the optimal angle. The X-OA-OB plane for women was 49.6±0.8)°-(59.9±1.1)°, the best angle X-OZ range (53.7±0.8)°. The range of nail path length was (91.4±2.3) mm for OA, (89.5±4.6) mm for OB and (94.2±2.1) mm for OZ. The OA level of female was (90.4±1.9) mm, (85.6±2.3) mm, OZ plane range (96.4±1.7) mm. The statistical results showed that in the best setting angle OZ, nail angle differences (F=4.276, P 0.05). OB, male and female, nail angle differences (F=8.153, P 0.05). Conclusion The iliac bone screw can be safely and effectively inserted into the iliac bone via the S3 block. In theory, the iliac bone screw is safe and stable through the O-Z needle entry point. The O-Z angle is also the best in Spinal pelvis fixation. Key words: Spinal pelvic fixation; Iliac screw; Spiral computer navigation; 3D printing and 3D reconstruction