33rd Annual Scientific Meeting proceedings

DA-CSM is a cause of progressive spinal cord and nerve root compression causing pain and neurologic debilitation in medium and large breed dogs. Several surgical techniques have been described to manage the condition, with variable success rates. In general, decompression of the spinal cord and nerve roots is either achieved directly (via ventral slot or dorsal laminectomy) or indirectly via vertebral distraction and stabilisation or fusion. The latter technique may be associated with lower peri-operative morbidity, however, challenges include inability to fuse the vertebrae and maintain vertebral distraction (i.e. to prevent vertebral subsidence).

Several devices (washers, screws, cages and other custom devices) have been described to assist vertebral distraction and fusion. Canine vertebral morphology is highly variable and a patient-specific approach may provide improved outcomes. Recent advances in in-silico planning and manufacturing processes have led to increased interest in custom implants. One such device is a titanium interbody spacer manufactured by selective laser melting, designed to conform to the individual patients vertebral end-plates, featuring a micro-porous structure. The conforming nature helps to distribute load across the end-plates and the structure mimics trabecular bone and assists bone in-growth.

In a recent study, the device was implanted alongside other vertebral stabilising implants in 9 dogs at a total of 13 intervertebral segments. This resulted in CT-determined fusion in 12/13 operated segments with favorable medium- and long-term outcomes. The technique was safe and effective, with no significant intra-operative complications. There were only minor implant-related complications on follow-up, none of which required revision surgery; in one case, subsidence was associated with mild clinical deterioration, the remaining eight cases improved.

Supporting stabilisation systems include mono-cortical locking plate fixation, bi-cortical screws with PMMA and bi-cortical poly-axial pedicle screws with rod fixation. Bi-cortical implantation is assisted with the design and manufacture of patient specific 3D drill guides.

Reference

Driver C.J, Lopez V, Walton B, Jones D, Fentem R, Tomlinson A and Rose J. Instrumented cervical fusion using custom designed end-plate conforming interbody devices with a micro-porous structure in nine dogs with disc-associated cervical spondylomyelopathy. Front. Vet. Sci. Sec. Veterinary Neurology and Neurosurgery Volume 10 – 2023. doi:10.3389/fvets.2023.1208593