Patient-specific drill template for C2 transoral pedicle insertion in complete reduction of atlantoaxial dislocation: cadaveric efficacy and accuracy assessments

BACKGROUND: The transoral atlantoaxial reduction plate (TARP) is an effective advance in the treatment of atlantoaxial dislocation (AAD) and can enable the performance of anterior atlantoaxial release, reduction, decompression, and internal fixation in a one-stage operation. However, accurate transoral C2 pedicle insertion (C2TOPI) remains a challenge. The aim of this study is to develop a grouped patient-specific drill template (PDT) specifically for AAD with complete reduction and, furthermore, to compare its efficacy and accuracy in facilitating C2TOPI. METHODS: After CT scanning, ten cadaveric C2 specimens were randomly assigned to two groups (the PDT and freehand group). A grouped PDT specifically for AAD with complete reduction was designed and manufactured. C2TOPI was performed using the PDT or the fluoroscopy-guided freehand technique. Postoperative CT scans were subsequently performed to analyze the deviations at the centroid of the cross section at the midpoint of the pedicle. Screw position grades were also assessed in both groups. RESULTS: Compared to the freehand group, the PDT group had a significantly shorter surgery time (p < 0.001). Significant differences between the two groups were observed in the absolute value of the deviations at the centroid of the pedicle on either the axial or sagittal planes (p < 0.05). No significant difference was found in the screw positions between the two groups (p > 0.05); however, two unacceptable breaches (20%) occurred in the freehand group. CONCLUSION: A specifically designed PDT could provide an accurate and easy-to-apply method for C2TOPI in AAD with complete reduction.