An Intraoperative Trajectory‐Determined Strategy of Patient‐Specific Drill Template for C(2) Transoral Pedicle Insertion in Incomplete Reduction of Atlantoaxial Dislocation: An In Vitro Study

OBJECTIVES: This study aims to explore a novel intraoperative trajectory‐determined strategy of grouped patient‐specific drill templates (PDTs) for transoral C(2) pedicle screw insertion (C(2)TOPI) for atlantoaxial dislocation (AAD) with incomplete reduction and to evaluate its efficiency and accuracy. METHODS: Ten cadaveric C(2) specimens were scanned by computed tomography (CT) and randomly divided into two groups (the PDT and freehand groups). A novel intraoperative trajectory‐determined strategy of grouped PDTs was created for AAD with incomplete reduction. C(2)TOPI was performed by use of the PDT technique and the fluoroscopy‐guided freehand technique. After surgery, the screw deviations from the centroid of the cross‐section at the midpoint of the pedicle and screw position grades were assessed in both groups. RESULTS: Compared to the freehand group, the PDT group had a significantly shorter surgery time than the freehand group (47.7 vs 61.9 min, P < 0.001). The absolute deviations from the centroids between the preoperative designs and postoperative measurements on the axial plane of the pedicle were 1.19 ± 0.25 mm in the PDT group and 1.82 ± 0.51 mm in the freehand group. On the sagittal plane of the pedicle, the corresponding values were 1.10 ± 0.33 mm in the PDT group and 1.70 ± 0.49 mm in the freehand group. The absolute deviations of the free‐hand group on both the axial and sagittal planes were higher than that of the freehand group (P < 0.05 and P < 0.05, respectively). For the grade of screw insertion position, nine (90%) were observed in type I and one (10%) in type II in the PDT group, whereas five (50%) were in type I, three (30%) were in type II, and two (20%) in type III in the freehand group. Statistical differences could not be found between the groups in terms of the screw positions (P > 0.05). CONCLUSION: The novel intraoperative trajectory‐determined strategy of grouped PDTs can be used as an accurate and feasible method for C(2)TOPI for AAD with incomplete reduction.