The Feasibility of Creating Image-Based Patient-Specific Drill Guides for the Atlantoaxial Instabilities Using Open-Source CAD Software and Desktop 3D Printers.

OBJECTIVE

C1/2 cervical pedicle screw fixation is a well-known procedure for treating severely damaged and unstable C1/2 fractures. On the other hand, C1/C2 screw fixation is not safe and can lead to potentially disastrous consequences. The importance of personalized 3-dimensional (3D) printed navigational guides in avoiding these consequences cannot be overstated.

METHODS

We retrospectively reviewed the neuroimaging data of 16 patients who had undergone fixation for treatment of C1/2 diseases. We created patient-specific C1/2 models and drill guide models using open-source 3D editing software and a desktop 3D printer. The drill guides were then placed over the respective vertebrae models and fixated with 3.5-mm screws. Following fixation, the parts were scanned with a thin-slice (01 mm) computed tomography scan, and the screw trajectories in the transverse and sagittal planes were measured at each level.

RESULTS

Of the total of 62 screws, 58 were type I (93.54%), 4 were type II (6.45%), and no screws were type III. The results showed that there was no significant deviation in the screw trajectories and the accuracy of the drill guides was 93.54%. In our study, type I and type II screws were deemed acceptable, and the acceptable rates of C1/2 screw fixation were 100%.

CONCLUSIONS

In this preclinical study, we demonstrated that it is possible to create patient-specific pedicle drill guides using open-source editing software and a commercially available desktop polylactic acid printer, resulting in high accuracy rates in pedicle screw placement in C1/2 patient models.