Cervical Spondylomyelopathy

Cervical fusion using an interbody device

 

Many techniques have been proposed to treat disc associated cervical spondylomyelopathy (DA-CSM) including direct and indirect decompression techniques. The latter are often used when faced with a significant traction-responsive lesion. Maintenance of distraction in these cases would in theory immediately and effectively relieve the extradural spinal cord compression caused by the redundant dorsal annulus and/or ligamentum flavum, relieve the spinal cord ischemia caused by compression of the ventral spinal artery and reopen the narrow intervertebral foramina decompressing the nerve roots/spinal nerves. Although the goal of stabilization is to treat instability in the short-term, long-term stability requires bony fusion, or the implant can fail which has been the most common cause of failure in these distraction-fusion techniques. Many reasons exist for the failure of the different techniques proposed to date including the type of interbody material used. The ideal interbody material should have an elastic modulus compatible with vertebral bone to limit the risk of crushing or perforating the adjacent endplates and conform to the shape of the endplates which varies from dog to dog as well as from individual disc space to space. Interbody material should also be biologically compatible to facilitate vertebral fusion for long-term stability. This is unlikely to be achieved with interbody material such as cement plug, washer or other metallic spacers. In this study, the authors test an endplate-conforming interbody device that was manufactured in titanium alloy with a micro-porous structure to try to meet these requirements and limit complications associated often with the use of indirect decompression techniques to treat DA-CSM.  Watch the webinar on this paper.

Comparison of Two Surgical Techniques for the Treatment of Canine Disc Associated-Cervical Spondylomyelopathy (DA-CSM)

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A variety of surgical techniques have been proposed for DA-CSM over the years with many authors claiming success rates in the region of 80%. Surgical techniques include direct decompression or indirect decompression such as vertebral distraction-stabilisation. However, very few studies have been published comparing surgical techniques especially on dogs presenting with similar pathology. Here dogs were selected if they had complete resolution of spinal cord compression on MRI after linear traction. 25 dogs were enrolled with 12 receiving a prosthetic disc (PD) implantation and 13 undergoing vertebral distraction-stabilisation (DS) with an intervertebral cage, ventral locking plates, and dorsal transarticular screws. Of importance, all dogs were followed-up for a minimum of 1 year and radiographically for at least 3 months with particular focus on the occurrence of subsidence.

Twenty-five dogs were enrolled. 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.