Accuracy and safety of three‐dimensionally printed animal‐specific drill guides for thoracolumbar vertebral column instrumentation in dogs: Bilateral and unilateral designs

Abstract

Objective: To evaluate the safety and accuracy of a unilateral three-dimensionally printed animal-specific drill guide (3DASDG) design for unilateral stabilization in the thoracolumbar vertebral column of dogs compared to a bilateral design. Study design: Cadaveric study. Sample population: Fifty-two corridors in one canine cadaver. Methods: Two 3DASDG designs with 2 drilling tubes each were created from T8 to L7 vertebrae. Fifty-two corridors were drilled on the right and the left sides by using unilateral and bilateral designs, respectively. Planned and postoperative trajectories (entry point, exit point, angle) were compared to establish the accuracy. Statistical analysis was used for accuracy comparison between designs. Safety was evaluated by using Zdichavsky classification. Results: Unilateral and bilateral drill guide designs were not different for entry point and angle deviations; however, they were different for the exit point deviations. Two corridors breached outside the vertebra. For all guides, mean entry and exit point deviations were less than 1 and 2 mm, respectively. The maximum entry or exit point deviation in both groups was 4.7 mm. The mean angle deviation was <3.5 , and the maximum angle deviation was 9.3. Conclusion: No difference was detected in accuracy of entry points and angle deviations between drill guide designs tested in normal vertebrae. The technique was classified as highly safe. Clinical significance: A unilateral drill guide design may be a safe alternative to bilateral guides for unilateral stabilization of the thoracolumbar vertebral column in dogs.

Accuracy and Safety of Image-Guided Freehand Pin Placement in Canine Cadaveric Vertebrae

“…Despite the fact that the freehand-guided technique has been the most commonly used technique for stabilization in dogs, its accuracy has never been reported to the best of our knowledge. The overall mean deviations that were identified for the entry (3.1 AE 1.2 mm) and exit points (6.3 AE 2.5 mm) were greater than those reported for 3D printed drill guide techniques (7,21). For the overall mean deviations of entry and exit points, Fujioka and colleagues reported values of 0.8 AE 0.4 and 0.9 AE 0.3 mm in the cadaveric segment of their study.…”

“…7 Guevar and colleagues reported values for two drill guide designs with overall mean deviation of entry points of 0.9 AE 0.9 and 0.9 AE 0.6 mm and for the exit points they were 1.4 AE 0.9 and 1.9 AE 0.8 mm. 21 The overall mean angle deviation of the corridors in the freehand technique was 7.6 AE 4.5 degrees that is less accurate than in two 3D printed drill guide designs (3,4 AE 1.7 and 3.5 AE 2.0 degrees). These two studies confirm that 3D printed is more accurate than the freehand-guided technique.…”

“…18,19 The use of novel technologies such as threedimensional (3D) printed drill guides is emerging as an accurate and safe technique to assist in spinal surgery. 7,20,21 Although stereotactic neuronavigation is nowadays commonly used in human surgery, 22,23 it has yet to be evaluated in veterinary medicine.…”

“…Our hypothesis was that the imaging technique would be reliable, and that the freehand technique would be safe but less accurate relative to the reported 3D-printed techniques. 7,21…”

Applications of 3‐dimensional printing in small‐animal surgery: A review of current practices

“…Unilateral guides minimized dissection without compromising accuracy in two cadaveric studies, justifying further investigations in live animals. 58,74 Future studies should focus on adjusting the composition and design of guides to minimize the guide footprint, improve its fit over the entry site and minimize interference with the drill and implants. Indeed, such interference could damage the guide and create debris in the surgical site, justifying the use of sterilized and biocompatible guides.…”