34th Annual Scientific Meeting proceedings

Objectives:

Intervertebral cage subsidence is a significant concern in managing disc-associated cervical spondylomyelopathy (DA-CSM) in dogs. The mechanical stability at the interface between vertebral endplate and cage significantly impacts the occurrence of subsidence. This study aimed to evaluate the distribution of subchondral bone mineral density (sBMD) within the canine C6-C7 vertebral motion unit as a marker for mechanical stability of the vertebral endplates.

Methods:

sBMD distribution was mapped in the vertebral motion unit C6-C7 of 15 sound middle- to large-breed dogs using computed tomography osteoabsorptiometry.

Results:

sBMD distribution in both the C6 and C7 vertebral endplates revealed a heterogeneous pattern. Low bone density was consistently observed in the central and dorsal regions of the nucleus pulposus contact area. In contrast, high sBMD was found mainly in the periphery, especially in the lateral and dorsal aspects of the annulus fibrosus contact area.

Conclusions:

At present, cervical spinal cages are predominantly positioned in a way which results in contact with the nucleus pulposus area and the ventral aspect of the annulus fibrosus area of the vertebral endplates. The presence of low sBMD at the central and centro-dorsal aspects of the nucleus pulposus area might explain the high incidence of cage subsidence in that specific region. Adjusting the current design of intervertebral cages to align with areas of higher sBMD could offer a promising strategy for reducing the occurrence of cage subsidence in dogs undergoing distraction, stabilization, and fusion procedures for DA-CSM.