[Study on the application of a new type of vertebral plate nail guide]

To explore safety and accuracy of novel C₂ laminar staple guide through in vitro experiments.

From January 2018 to June 2018, 40 patients who underwent three-dimensional CT of cervical spine were selected, including 21 males and 19 females, heighted from 165 to 180 cm with an average of (172.9±9.5) cm, aged from 38 to 55 years old (51.1±12.8) years old, excluding patients with axis lamina defect and hypoplasia. Two sets of 3D printed specimens were made from the three-dimensional CT data of cervical spine of each patient, and both of than were used for the in vitro nailing experiment. According to different nail placement methods, in vitro experimental part of this experiment was divided into guide nail placement group and hand nail placement group, 40 pieces in each group. At the same time, the three-dimensionalmodel of cervical spine of 40 patients was reconstructed on computer, and the ideal needle point data and inclination angle were obtained by computer simulation of the nail placement. This is 3D simulation nail placement group, 40 pieces. With vitro experiment, the risk level of screw placement, the position of needle exit point and inclination angle were measured in guide nail group and hand nail group. Based on the accuracy of needle point and inclination angle of nail path, the data of guide nail group, the hand nail group and 3D simulation nail group were compared, and the data of each group were statistically analyzed to determine the accuracy.

In guide nail group, 75 screws were acceptable and 5 were dangerous. The acceptable rate was 94%, and the double cortical rate was 93%. There were 62 position-acceptable screws in hand nail group, and 18 positions were dangerous, with an acceptable rate of 78% and a double cortical rate of 33%. The difference between two groups was statistically significant (P<0.05). There was no significant difference in accuracy of needle exit point and inclination angle of nail path between guide nail group and 3D simulation nail group (P>0.05), but there was significant difference in the accuracy of needle exit point and inclination angle of nail path between hand nail group and 3D simulation nail group (P<0.05).

The guide is universal, with stable structure, accurate guidance, and easy operation. It could be placed with bilateral lamina screws at the same time, shortening the time of nail placement, avoiding collision of two way cross screws, increase the rate of double cortex. Ultimately, efficiency and security can be improved.