Ex vivo comparison of pin placement with patient-specific drill guides or freehand technique in canine cadaveric spines

Abstract

Objective: To compare vertebral implant placement in the canine thoracolumbar spine between 3D-printed patient-specific drill guides (3DPG) and the conventional freehand technique (FH).

Study design: Ex vivo study.

Animals: Cadaveric canine spines (n = 24).

Methods: Implant trajectories were established for the left and right sides of the T10 through L6 vertebrae based on computed tomography (CT) imaging. Customized drill guides were created for each vertebra of interest. Each cadaver was randomly assigned to one of six veterinarians with varying levels of experience placing vertebral implants. Vertebrae were randomly assigned a surgical order and technique (3DPG or FH) for both sides. Postoperative CT images were acquired. A single, blinded observer assessed pin placement using a modified Zdichavsky classification.

Results: A total of 480 implants were placed in 240 vertebrae. Three sites were excluded from the analysis; therefore, a total of 238 implants were evaluated using the FH technique and 239 implants using 3DPG. When evaluating implant placement, 152/239 (63.6%) of 3DPG implants were considered to have an acceptable placement in comparison with 115/248 (48.32%) with FH. Overall, pin placement using 3DPG was more likely to provide acceptable pin placement (p < .001) in comparison with the FH technique for surgeons at all levels of experience.

Conclusion: The use of 3DPG was shown to be better than the conventional freehand technique regarding acceptable placement of implants in the thoracolumbar spine of canine cadavers.

Clinical significance: Utilizing 3DPG can be considered better than the traditional FH technique when placing implants in the canine thoracolumbar spine.