Accuracy of Three-Dimensionally Printed, Patient-Specific Drill Guides for Implant Placement in Canine Cervical Vertebrae: A Cadaveric Study

The objective of this study was to assess the accuracy of autoclavable, three-dimensionally (3D) printed drill guides (3DPG) created with a rapid printing protocol and utilized by both an experienced and inexperienced surgeon in constraining the trajectory of drill tracts to intended corridors within canine cervical vertebrae. The 3DPG were designed using computed tomographic (CT) images of six complete cadaveric canine cervical vertebral columns and used to create drill tracts in all vertebrae by both an experienced and a novice surgeon. Repeat CT imaging was used to assess the entry point (EPD) and angular deviation (AD) of the actual versus planned drill tracts. Unintended cortical bone violations were also assessed. A total of 80 3DPG were used to create 144 drill tracts in 42 vertebrae. The overall mean EPD was 1.1 mm (median 0.9 mm, range 0.1-5.1 mm) and the overall mean AD was 7.3° (median 5.2°, range 0.5-33.8°). There were no differences in overall EPD (<i>p</i> = 0.85) or AD (<i>p</i> = 0.20) between the inexperienced and novice surgeons. There were no unintended cortical bone breaches. These 3DPG allowed the creation of safe and accurate drill tracts within the canine cervical spine by both an experienced and an inexperienced surgeon.