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

Abstract

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 AE 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 AE 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.

Accuracy and Efficacy of a Patient-Specific Drill Guide Template System for Lumbosacral Junction Fixation in Medium and Small Dogs: Cadaveric Study and Clinical Cases

“…The lamina cover of drill guide template is fabricated of a flexible silicone material that fits tightly the vertebral arch, and the drill sleeve should be fabricated of a hard acrylic material that is resistant to loads. Although the deviation between the preoperative planned trajectories and drilled trajectories in this study was larger than that of the thoracolumbar vertebrae in our previous study (14), all drill holes were completely located within the bone, and no intraoperative complications were experienced in the clinical cases.…”

“…We designed and fabricated the drill guide templates as we reported previously (14). Briefly, bone processing data were extracted from the DICOM data using image processing software (VG Studio Max, Volume Graphics GmbH, Heidelberg, Germany Mimics, Materialize, Leuven, Belgium) and transferred to 3D modeling software (Freeform, Data Design, Nagoya, Japan) to generate a 3D reconstruction model.…”

“…Subsequently, fusion images were made by superimposing the postoperative MPR image on the preoperative MPR image, and the coordinates of the entry and exit points of the drill holes on the fusion images were recorded (Figure 4). Deviations in the coordinates of the entry and exit points in each dimension (x, y, z) were evaluated, as in our previous report (14). To evaluate the safety of the drill guide templates, drill FIGURE 2 | Design of patient-specific drill guide templates.…”

“…We previously reported a patient-specific drill guide template (14), which was developed as an inexpensive device to accurately guide spinal fixation screws in the thoracolumbar vertebrae of dogs. The present study assessed the accuracy of patient-specific drill guide templates for screw placement in the lumbosacral junctions of canine cadavers.…”

Atlanto‐axial ventral stabilisation using 3D‐printed patient‐specific drill guides for placement of bicortical screws in dogs

“…Rigid ventral stabilisation typically involves placement of screws stabilised by either plates or polymethylmethacrylate (PMMA). Accurate free-hand screw insertion into C1 and C2 vertebrae is challenging due to the narrow safe corridors, and carries the risk of iatrogenic damage of spinal cord, vasculature and nerves in both human and veterinary medicine (Cong et al 2015, Fujioka et al 2018. To reduce such risks, threedimensional (3D) patient-specific drill guides have been developed in human medicine and have been shown to improve safety and accuracy of cervical pedicle screw placement compared to free-hand and fluoroscopic techniques (Bundoc et al 2017).…”