Development of a patient specific 3D-printed drill guide for ventral slot surgery in dogs

Abstract

Complications associated with ventral slot decompression for cervical intervertebral disc extrusion have been reported in 9.9% of cases and include vertebral subluxation, hemorrhage, and neurologic deterioration. To minimize the risk of complications, slot dimensions should not exceed 33% of the length or width of the vertebral body. Achieving these dimensions intraoperatively may be challenging, thus use of a surgical guide may result in more accurate outcomes. The objective of this study was to compare accuracy and precision of ventral slot dimensions created using a 3D-printed patient-specific surgical guide or the conventional freehand technique in canine cadavers. CT data was used to create patient-specific surgical guides from 8 large breed canine cadavers. Intervertebral sites were randomized to undergo either a guided (n=12) or freehand (n=12) ventral slot by a novice surgery resident. Postoperative CT images were used to compare ventral slot dimensions, shape, and position. There was a significant difference between the intended and postoperative slot lengths of the freehand slots (p<0.01). Dimensions of the guided ventral slots were not statistically different from the planned dimensions. Use of the guides resulted in improved precision for ventral slot positioning relative to midline, divergence from midline, and slot shape (difference in coefficient of variations, 32%, 4%, and 40% respectively). This study confirms that the use of a 3D-printed patient specific surgical guide improves accuracy of ventral slot creation in canine cadavers and improves surgical precision when used by a single novice surgical resident. Future studies investigating the benefit of these guides when used by experienced surgeons and in live patients are warranted