Ex vivo computed tomography evaluation of loading position on morphometry of the caudal cervical intervertebral disk spaces of dogs

Abstract

OBJECTIVE To provide an objective, quantitative morphometric description of the caudal cervical intervertebral disk (IVD) spaces of dogs. SAMPLE Vertebral specimens consisting of C4 through C7 from 5 medium-sized dogs. PROCEDURES CT images were obtained with the specimens positioned in neutral, flexion, extension, and lateral bending positions. Size and shape of the cranial and caudal end plates, angle between the end plates (IVD wedge angle), and craniocaudal distance (IVD width) between end plates for the 4 loading positions were measured and compared for the 3 segments (C4-5, C5-6, and C6-7). RESULTS End plate size and shape, IVD wedge angle, and IVD width were not significantly different among the 3 segments. Caudal cervical end plates were consistently larger than cranial cervical end plates. The IVD wedge angle ranged from −4.8° to 15.2°. Flexion induced a reduction in IVD width in the ventral portion of the IVD, whereas extension induced a decrease in width in the dorsal portion of the IVD. Central IVD width remained unchanged among the loading positions. CONCLUSIONS AND CLINICAL RELEVANCE Unique morphometric and dynamic characteristics of the caudal cervical IVD space of dogs were detected. These findings may help investigators when designing IVD prostheses for dogs with cervical spondylomyelopathy.

Ex vivo Evaluation of the Dynamic Morphometry of the Caudal Cervical Intervertebral Disc Spaces of Small Dogs and Cats

“…The experimental setup was similar as previously described (20). However, due to the smaller size of the vertebrae, small adaptions to the testing setup had to be made.…”

“…Inserting the pins into the PMMA rather than into the vertebrae avoided iatrogenic fractures of the vertebrae. Specimens were loaded in a modified 3D-printed loading jig similar as previously used (20). In comparison with the previously used jig, the openings in the 3D-printed blocks were adapted to the smaller size of the K-wires (2.5 mm).…”

“…In comparison with the previously used jig, the openings in the 3D-printed blocks were adapted to the smaller size of the K-wires (2.5 mm). Otherwise, the jig was similar to the one used by Knell et al (20).…”

“…The morphometric differences in the caudal cervical spine of small breeds dogs and cats compared with medium or large dogs is one hypothetical explanation for the difference of CSM prevalence. A recent study investigating the morphometric parameters of the caudal cervical spine of medium-sized dogs, including the IVD wedge angle and IVD width, reported specific morphometric characteristics and significant changes of these parameters, when different loading conditions were applied (20). This study included specimens from mixed-breed dogs weighing 25-35 kg (21)(22)(23).…”

“…Therefore, the purpose of this study was to investigate the morphometry and kinematic behavior of the caudal cervical spine in small-breed dogs and cats, as it has been done previously in medium-sized dogs (20). We hypothesized that:…”