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

Abstract

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.

An Intraoperative Trajectory‐Determined Strategy of Patient‐Specific Drill Template for C2 Transoral Pedicle Insertion in Incomplete Reduction of Atlantoaxial Dislocation: An In Vitro Study

“…All specimens were handled by the same procedures in our previously published protocols 18 . The CT data were imported into Mimics software version 14.11 (Materialize Corp., Leuven, Belgium) to obtain 3D reconstruction models of the C 1 and C 2 vertebrae.…”

“…(A) The midpoint and corresponding cross‐section of each pedicle were determined. (B) After the contour of the cross section was fitted by a maximum ellipse, the centroid was calculated from the maximum ellipse (reprinted from our previous research 18 with permission from Copyright Clearance Center).…”

“…The sagittal plane deviations towards the superior and inferior sides were recorded as positive and negative values, respectively. Another intuitive assessment criterion was the grade of the pedicle screw insertion position, which were graded according to the modified All India Institute of Medical Sciences outcome‐based classification 18 :…”

“…However, these devices are relatively expensive, as well as the operative procedures being complicated and time‐consuming, which influences their wide application in clinical trials 13,17 . Patient specific drill templates (PDTs) produced by 3D printing were then introduced to assist C 2 TOPI, which have been confirmed to improve the accuracy and efficacy of C 2 TOPI as well as obviate complex equipment and time‐consuming procedures 18,19 . However, these strategies used for PDTs were mainly based on the pre‐set trajectory, which could not meet the demands for all kinds of intraoperative reduction in AAD.…”

Retropharyngeal Reduction Plate for Treatment of Irreducible Atlantoaxial Dislocation: A Cadaveric Test and Finite Element Analysis

“…The instability of the atlantoaxial joint can lead to a variety of symptoms, such as local pain, limb anesthesia, urination dysfunction, defecation dysfunction, and even death. Consequently, if AAD is not treated in a timely and appropriate manner, the displacement may become irreversible [1][2][3][4]. If observation of the dynamic X-ray shows that the reduction of the atlantoaxial joint failed with skeletal traction under general anesthesia, AAD is considered irreducible [5].…”