Preparation and Assessment of an Individualized Navigation Template for Lower Cervical Anterior Transpedicular Screw...

Prospective trial.

To establish an individualized navigation template for safe and accurate insertion of lower cervical anterior transpedicular screw (ATPS) based on a three-dimensional (3D) printing technique.

Conventional screw insertion manually under fluoroscopy easily leading to deviation of ATPS screw channel, cervical instrumentation procedures demand the need for a precise technique for screw placement.

Twenty adult cervical spine specimens (10 men and 10 women, with a mean age of 50.29 ± 6.98) were selected for computed tomography pre- and postoperatively. A 3D lower cervical spine model was reconstructed using Mimics software to measure the screw-related parameters and generate a reverse template with optimal screw channel as well as a prototype using 3D printing. Assisted by the navigation template, bilateral ATPS were inserted into the cadavers.

The mean outer width and height of pedicle were 5.31 ± 1.23 and 6.78 ± 1.10 mm, respectively. The average length, sagittal, and axial angles of the optimal screw channel obtained through the optimal entry point were 36.34 ± 4.39 mm, 40.67° ± 5.10°, and 93.7° ± 7.96°, respectively. The adjustable safe ranges of sagittal and axial angles were 3.89° ± 1.13° and 5.64° ± 0.97°, respectively. The axial and sagittal accuracies of the 200 screws were 99.5% and 97%, respectively. The average deviations of the actual entry point and the preset opening in the X, Y, and Z axes were 0.39 ± 0.43, 0.21 ± 0.41, and 0.29 ± 0.14 mm, respectively (P > 0.05).

An individualized ATPS navigation template was developed using Mimics software and 3D printing prototyping, based on computed tomography, for highly accurate screw insertion.

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