RESUMEN
OBJECTIVE: The main aim of this pilot study was to assess the feasibility of spinal neuronavigation for plate fixation of lumbar vertebrae in miniature breed dogs using a surgical navigation system in combination with a custom-made reference array. STUDY DESIGN: This was an experimental cadaveric study in five miniature breed dogs. METHODS: A 4-hole locking plate with four 2.0-mm locking screws was placed on two adjacent lumbar vertebrae using a neuronavigation system consisting of a mobile cone beam computed tomography linked to a navigation system. The procedure was performed by a novice surgeon. The plate and screw positions were assessed for surgical safety using predefined criteria. Surgical accuracy was determined by the deviation of entry and exit points between pre- and postoperative images. RESULTS: A total of five plates and 20 screws were placed. In 85% (17/20), screws were placed appropriately. The median entry point deviation was 1.8 mm (range: 0.3-3.7) and the median exit point deviation was 1.6 mm (range: 0.6-5). CONCLUSION: Achievement of surgical accuracy in the placement of screws for fixation of lumbar vertebral plates in small breed dogs using neuronavigation with a custom-made reference array by a novice surgeon resulted in surgical safe plate placement in four of the five cadavers. Therefore, we judge the method as promising, however, further studies are necessary to allow the transfer of image-guided navigation for lumbar plate fixation into the clinic.
RESUMEN
OBJECTIVE: To compare the biomechanical properties of atlantoaxial joints (AAJs) in canine vertebral column specimens stabilized with 4 techniques (dorsal wire, modified dorsal clamp, ventral transarticular pin, and augmented ventral transarticular pin fixation) after transection of the AAJ ligaments. SAMPLE: 13 skull and cranial vertebral column segments from 13 cadaveric toy-breed dogs. PROCEDURES: Vertebral column segments from the middle aspect of the skull to C5 were harvested and prepared; AAJ ligament and joint capsule integrity was preserved. The atlantooccipital joint and C2 to C5 vertebral column segments were fixed with 2 transarticular Kirschner wires each. The occipital bone and caudalmost aspect of each specimen were embedded in polymethylmethacrylate. Range of motion of the AAJ under shear loading conditions up to 15 N was determined for each specimen during the third of 3 loading cycles with intact ligaments, after ligament transection, and after stabilization with each technique in random order. For each specimen, a load-to-failure test was performed with the fixation type tested last. RESULTS: All stabilization techniques except for dorsal clamp fixation were associated with significantly decreased AAJ range of motion, compared with results when ligaments were intact or transected. The AAJs with dorsal wire, ventral transarticular pin, and augmented ventral transarticular pin fixations had similar biomechanical properties. CONCLUSIONS AND CLINICAL RELEVANCE: Dorsal wire, ventral transarticular pin, and augmented ventral transarticular pin fixation increased rigidity, compared with results for AAJs with intact ligaments and for AAJs with experimentally created instability. Additional studies are needed to assess long-term stability of AAJs stabilized with these techniques.