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

Abstract

ObjectiveTo 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 designA retrospective clinical study.AnimalsNine medium and large breed dogs.MethodsMedical 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.ResultsNine 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.ConclusionEnd-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 significanceThe technique described can be used to distract and fuse cervical vertebrae in dogs with DA-CSM, with favorable medium-and long-term outcomes.

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

“…Its incidence in humans is reported to range from 0% to as high as 83%, with a mean rate of 21.1% [14]. In the context of dogs, studies have documented cage subsidence across a wide spectrum, with incidence rates spanning from 11% to 100% in treated spinal articulations [3][4][5][8][9][10][11][15][16][17][18][19]. Among these investigations, a consistent finding is that the cranial endplate of the caudal vertebra is the most commonly affected site.…”

“…Custom-designed cages have previously demonstrated success in dogs with DA-CSM [18,19]. The enhancement of these designs primarily revolved around molding the cage to closely match the curvature of the cranial and caudal endplates.…”

Accuracy and safety of freehand vs. end-on fluoroscopic guided drill-hole placement in canine cadaveric thoracic, lumbar and sacral vertebrae

“…Instrumentation is typically bilateral, although unilateral fixation has been described ( 5 , 6 ). Potential techniques include the use of pins or screws and polymethylmethacralate (PMMA) bone cement ( 2 , 7 , 8 ), locking bone plates ( 9 ), clamp rod internal fixator ( 10 ), external fixator ( 11 ), and polyaxial pedicle screw and rods ( 12 ). Preferred insertion points and trajectories have been published ( 13 ) with the main target for bone purchase being the vertebral bodies, although the vertebral pedicles are another attractive option particularly in the caudal lumbar spine ( 14 ).…”

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

“…Various surgical approaches for the treatment of DA-CSM have been described. The proposed surgical techniques are commonly divided into direct decompressive (by a ventral or dorsal approach), indirect decompressive with motion preservation (total disc replacement by arthroplasty), and indirect decompressive without preservation of motion [ 19 ]. The latter involves vertebral distraction and stabilization in order to restore the intervertebral disc and foraminal width, and to stabilize the vertebral segment to prevent ongoing dynamic concussive injury to the spinal cord [ 10 , 11 , 20 , 21 ].…”