Lumbosacral junction pedicle-probing technique for implant corridors in cats: feasibility and limitations

To describe a pedicle-probing technique for determining safe implant corridors at the seventh lumbar vertebra (L7)-first sacral vertebra (S1) in cats and evaluate the feasibility, safety, positioning, and trajectory of drill tracts created with this technique.

CT of lumbosacral spine was performed in 13 feline cadavers to determine safe pedicle corridors. Using the pedicle-probing technique, drill tracts were created in the pedicles of L7 and S1 with a blunt probe followed by a drill bit. Postoperative grading of pedicle drill tracts for canal breach was performed on CT using a 4-point classification. Drill tract positioning, trajectory, and proximity to ventral S1 foramina were also evaluated.

At L7, 20 of 26 drill tracts (76.9%) were fully contained within the pedicle, 3 (11.5%) had > 50% of their diameter within the pedicle, 1 (3.8%) had < 50% of its diameter within the pedicle, and 2 (7.7%) were fully within the vertebral canal. At S1, 24 drill tracts (92.3%) were fully contained within the pedicle, and 2 (7.7%) had > 50% of their diameter within the pedicle.

The pedicle-probing technique was associated with a high rate of vertebral canal breach at L7, whereas a greater proportion of drill tracts at S1 were fully contained within the pedicles.

The pedicle-probing technique can facilitate safe implant corridors at L7-S1 in cats; however, a high rate of breaches at L7 and variations in drill tract positioning and trajectory emphasize technical difficulty.