A novel patient-specific drill guide template for stabilization of thoracolumbar vertebrae of dogs: cadaveric study and clinical cases

Objective To evaluate the accuracy and safety of a novel patient-specific drill guide template for stabilizing the thoracolumbar vertebrae of dogs. Study design Cadaveric experimental study and prospective case series. Sample population Cadaveric canine thoracolumbar vertebral specimens (n = 3) and clinical cases of thoracolumbar spinal instability (n = 4). Methods Computed tomography data of the thoracolumbar spines were obtained before surgery, and images were imported into imaging software. Optimum screw trajectories were selected for each vertebra, and drill guide templates were designed and fabricated with a 3-dimensional printing system. Drill guide templates were applied to cadaveric spine and clinical cases. Computed tomography imaging was performed after surgery, and planned and postoperative trajectories were compared to estimate the accuracy and safety of the drill guide templates. Results Twenty-two drill holes were made in cadaveric spinal specimens. All drill holes were completely located in the bone. The overall mean screw deviation was 0.88 +/- 0.36 mm. In clinical cases, 29 screws were placed in thoracolumbar vertebrae. Most (89.6%) of these screws were placed without evidence of vertebral canal invasion. One (3.5%) screw perforated the bone structure. The overall mean screw deviation was 1.16 +/- 0.56 mm. Conclusion Drill guide templates were useful for accurate intraoperative screw navigation in thoracolumbar fixation in small dogs. Clinical significance The use of drill guide templates can be considered as an aid to safety and accuracy of screw placement in canine thoracolumbar instabilities.