Computed Tomography Guided Sterotaxic Navigation Of The Canine Thoracolumbar Spine

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Archambault N, Coates JR, Pathau P, et al.

Computed Tomography Guided Sterotaxic Navigation of the Canine Thoracolumbar Spine. ACVIM Forum. Indianapolis, Indiana, 2015;649.

Implant placements into the canine thoracolumbar spine carry a formidable risk of vertebral canal violation and disruption of juxta- vascular and neural structures. Surgical planning using cross sectional imaging and stereotaxy can guide implant placement and mitigate surgical complications. The purpose of this study was to investigate the safety and clinical application of a computed tomography (CT) guided stereotactic technique for use during implant placement in the canine thoracolumbar spine. CT studies using 0.63mm slice thickness were performed from T12 to L3 vertebral segments in 6 medium sized cadavers. A bilateral dorsal approach of the thoracolumbar spine was used to simulate exposure of the same vertebrae. Stereotactic navigation was achieved with commercially available neuronavigation software. A novel subject tracker and 3-dimentional CT reconstructions were used for the registration process. A mechanized air drill allowed for a bicortical vertebral body trajectory via CT guided navigation. Stereotactic guided trajectories were stored. A Steinmann pin was placed into the drill hole to trace the trajectory with a post-operative CT. Vertebral bodies were disarticulated and removed to visually examine for canal violation. Stereotactic guided trajectory and postoperative CT trajectory angle and depth values were compared statistically a using Wilcox rank sum analysis at a significance value of 0.05. A total of 59 trajectories were drilled, with no vertebral canal violations (partial or full). Fifty three of 59 (90%) trajectories involved the vertebral midline or contralateral vertebral body. Mean difference between stereotactic guided trajectory and postoperative CT trajectory angle was 3.8 ± 2.2 degrees (range: 0.3 to 8.3 degrees). Mean difference between stereotactic guided trajectory and postoperative CT trajectory depth was 1.5 ± 1.1 mm (range: 0 to 4mm). There was no significant difference between stereotactic guided and postoperative CT trajectory angle and depth measurements. Computed tomography guided vertebral stereotaxy provides an accurate means of implant placement into the canine thoracolumbar vertebral column, reducing the risk of damage to vital structures and spinal cord disruption. Additionally, CT guided stereotactic navigation afforded excellent bone purchase.