Surgical management and long-term outcome of dogs with cervical spondylomyelopathy with an anchored intervertebral titanium device

Mapping Subchondral Bone Density Distribution in the Canine C6-C7 Vertebral Endplates: A CT-OAM Study

Intervertebral cage subsidence is a common complication in treating disc-associated cervical spondylomyelopathy in dogs. The mechanical stability of the vertebral endplate in contact with the cage is crucial to preventing subsidence. This study aims to assess subchondral bone mineral density (sBMD) in the canine vertebral endplate (specifically, the C6-C7 vertebral motion unit) as a measure of its mechanical stability. The sBMD distribution was mapped for the C6 caudal and C7 cranial vertebral endplates in 15 middle- to large-breed dogs using computed tomography osteoabsorptiometry. The sBMD distribution in the canine C6 and C7 vertebral endplates exhibited a heterogeneous pattern, with lower density observed in the central and dorsal contact areas of the nucleus pulposus, where common subsidence occurs. Our results suggest a potential need to redesign intervertebral cages to ensure that contact areas align with regions of higher bone density. A broad-based design extending toward the lateral and dorsal aspects of the annulus fibrosus contact area may enhance stability.

Treatment of Canine Disc-Associated Cervical Spondylomyelopathy with a Cervical Distraction-Stabilization Technique (C-LOX Combined with LCP Plate) and Clinical Outcomes

Canine disc-associated cervical spondylomyelopathy (DA-CSM) is a form of caudal CSM, characterized by the compression of the spinal cord and nerve roots due to an intervertebral disc protrusion. It is more frequent in large canine breeds. A variety of surgical techniques has been proposed for DA-CSM. The aim of the study was to evaluate the outcomes of a cervical distraction-stabilization technique using an intervertebral anchored fusion device (C-LOX) combined with a locking compression plate (LCP plate) for the treatment of DA-CSM in dogs, based on clinical and radiographical follow-up data. Thirteen dogs affected by DA-CSM were included in the study. After the surgical procedure, an improvement in neurological status was documented in 9/13 cases. This cervical distraction-stabilization technique seems to be a valuable surgical alternative to treat this canine pathology.

Instrumented cervical fusion using patient specific end-plate conforming interbody devices with a micro-porous structure in nine dogs with disk-associated cervical spondylomyelopathy

Objective

To report the medium and long-term outcome of nine dogs with disk-associated cervical spondylomyelopathy (DA-CSM), treated by instrumented interbody fusion using patient specific end-plate conforming device that features a micro-porous structure to facilitate bone in-growth.

Study design

A retrospective clinical study.

Animals

Nine medium and large breed dogs.

Methods

Medical records at two institutions were reviewed between January 2020 and 2023. Following magnetic resonance imaging (MRI) diagnosis of DA-CSM, pre-operative computed tomography (CT) scans were exported to computer software for in-silico surgical planning. Interbody devices were 3D-manufactured by selecting laser melting in titanium alloy. These were surgically implanted at 13 segments alongside mono-or bi-cortical vertebral stabilization systems. Follow-up included neurologic scoring and CT scans post-operative, at medium-term follow up and at long-term follow-up where possible. Interbody fusion and implant subsidence were evaluated from follow-up CT scans.

Results

Nine dogs were diagnosed with DA-CSM between C5-C7 at a total of 13 operated segments. Medium-term follow up was obtained between 2 and 8 months post-operative (3.00 ± 1.82 months). Neurologic scoring improved (p = 0.009) in eight of nine dogs. Distraction was significant (p < 0.001) at all segments. Fusion was evident at 12/13 segments. Subsidence was evident at 3/13 operated segments but was only considered clinically relevant in one dog that did not improve; as clinical signs were mild, revision surgery was not recommended. Long-term follow up was obtained between 9 and 33 months (14.23 ± 8.24 months); improvement was sustained in 8 dogs. The dog that suffered worsened thoracic limb paresis at medium-term follow up was also diagnosed with immune-mediated polyarthropathy (IMPA) and was euthanased 9 months post-operative due to unacceptable side-effects of corticosteroid therapy.

Conclusion

End-plate conforming interbody devices with a micro-porous structure were designed, manufactured, and successfully implanted in dog with DA-CSM. This resulted in CT-determined fusion with minimal subsidence in the majority of operated segments.

Clinical significance

The technique described can be used to distract and fuse cervical vertebrae in dogs with DA-CSM, with favorable medium-and long-term outcomes.

Comparison of Two Surgical Techniques for the Treatment of Canine Disc Associated-Cervical Spondylomyelopathy

Objective

To compare prosthetic disc and vertebral distraction stabilization in dogs with disc-associated cervical spondylomyelopathy (DA-CSM).

Study Design

A retrospective clinical study.

Animals

25 dogs.

Methods

Dogs presenting with clinical signs and MRI findings compatible with DA-CSM underwent surgery. Implantation of the Adamo's prosthetic disc (PD) or vertebral distraction-stabilization (DS) with intervertebral cage, ventral locking plates, and dorsal transarticular screws was performed. All dogs were followed-up and evaluated clinically for a minimum of 1 year and radiographically for at least 3 months. In particular, we focused on the evaluation of subsidence (the degree of vertebral collapse).

Results

Twenty-five dogs were enrolled: 12 with PD implantation and 13 with DS implantation. Of these, 24 dogs were followed-up at 1 year. Overall, 12 dogs improved (4 PD and 8 DS), eight were stable (4 PD and 4 DS), and four deteriorated (3 PD and 1 DS). Deterioration was more common in PD cases, especially soon after surgery. In a few PD cases, a second surgery was necessary. The most common complication in dogs with DS was discospondylitis. Subsidence was detected in 11 PD and 7 DS dogs. Subsidence was more severe and occurred sooner after surgery in PD cases compared to DS cases. DS cases were more prone to clinical improvement and less prone to subsidence than PD cases in this study. However, the statistical evidence was weak owing to the small sample size.

Conclusion

The preliminary results suggest that prosthetic disc implantation is more prone to clinical and radiographic failures than distraction stabilization.

Clinical Relevance

The DS technique is a valuable surgical option for treating dogs with DA-CSM, with favorable short- and long-term clinical and radiographic outcomes.