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  • Author or Editor: Benjamin Voumard x
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Abstract

OBJECTIVE

To determine whether a customized unilateral intervertebral anchored fusion device combined with (vs without) an intervertebral spacer would increase the stability of the L1-L2 motion segment following complete intervertebral diskectomy in canine cadaveric specimens.

SAMPLE

Vertebral columns from T13 through L3 harvested from 16 skeletally mature Beagles without thoracolumbar disease.

PROCEDURES

Complete diskectomy of the L1-2 disk was performed in each specimen. Unilateral stabilization of the L1-L2 motion segment was performed with the first of 2 implants: a unilateral intervertebral anchored fusion device that consisted of a locking compression plate with or without an intervertebral spacer. The resulting construct was biomechanically tested; then, the first implant was removed, and the second implant was applied to the contralateral side and tested. Range of motion in flexion and extension, lateral bending, and torsion was compared among intact specimens (prior to diskectomy) and constructs.

RESULTS

Compared with intact specimens, constructs stabilized with either implant were as stable in flexion and extension, significantly more stable in lateral bending, and significantly less stable in axial rotation. Constructs stabilized with the fusion device plus intervertebral spacer were significantly stiffer in lateral bending than those stabilized with the fusion device alone. No significant differences in flexion and extension and rotation were noted between implants.

CONCLUSIONS AND CLINICAL RELEVANCE

Findings did not support the use of this customized unilateral intervertebral anchored fusion device with an intervertebral spacer to improve unilateral stabilization of the L1-L2 motion segment after complete L1-2 diskectomy in dogs.

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in American Journal of Veterinary Research

Abstract

OBJECTIVE

To evaluate intradiskal pressure (IDP) in the C6-7 intervertebral disk (IVD) after destabilization and distraction-fusion of the C5-C6 vertebrae.

SAMPLE

7 cadaveric C4-T1 vertebral specimens with no evidence of IVD disease from large-breed dogs.

PROCEDURES

Specimens were mounted in a custom-made 6 degrees of freedom spinal loading simulator so the C5-C6 and C6-C7 segments remained mobile. One specimen remained untreated and was used to assess the repeatability of the IDP measurement protocol. Six specimens underwent 3 sequential configurations (untreated, partial diskectomy of the C5-6 IVD, and distraction-fusion of the C5-C6 vertebrae). Each construct was biomechanically tested under neutral, flexion, extension, and right-lateral bending loads. The IDP was measured with a pressure transducer inserted into the C6-7 IVD and compared between the nucleus pulposus and annulus fibrosus and across all 3 constructs and 4 loads.

RESULTS

Compared with untreated constructs, partial diskectomy and distraction-fusion of C5-C6 decreased the mean ± SD IDP in the C6-7 IVD by 1.3 ± 1.3% and 0.8 ± 1.3%, respectively. During motion, the IDP remained fairly constant in the annulus fibrosus and increased by 3.8 ± 3.0% in the nucleus pulposus. The increase in IDP within the nucleus pulposus was numerically greatest during flexion but did not differ significantly among loading conditions.

CONCLUSIONS AND CLINICAL RELEVANCE

Distraction-fusion of C5-C6 did not significantly alter the IDP of healthy C6-7 IVDs. Effects of vertebral distraction-fusion on the IDP of adjacent IVDs with degenerative changes, such as those in dogs with caudal cervical spondylomyelopathy, warrant investigation.

Restricted access
in American Journal of Veterinary Research

Abstract

OBJECTIVE

To compare the biomechanical properties of atlantoaxial joints (AAJs) in canine vertebral column specimens stabilized with 4 techniques (dorsal wire, modified dorsal clamp, ventral transarticular pin, and augmented ventral transarticular pin fixation) after transection of the AAJ ligaments.

Sample

13 skull and cranial vertebral column segments from 13 cadaveric toy-breed dogs.

PROCEDURES

Vertebral column segments from the middle aspect of the skull to C5 were harvested and prepared; AAJ ligament and joint capsule integrity was preserved. The atlantooccipital joint and C2 to C5 vertebral column segments were fixed with 2 transarticular Kirschner wires each. The occipital bone and caudalmost aspect of each specimen were embedded in polymethylmethacrylate. Range of motion of the AAJ under shear loading conditions up to 15 N was determined for each specimen during the third of 3 loading cycles with intact ligaments, after ligament transection, and after stabilization with each technique in random order. For each specimen, a load-to-failure test was performed with the fixation type tested last.

RESULTS

All stabilization techniques except for dorsal clamp fixation were associated with significantly decreased AAJ range of motion, compared with results when ligaments were intact or transected. The AAJs with dorsal wire, ventral transarticular pin, and augmented ventral transarticular pin fixations had similar biomechanical properties.

CONCLUSIONS AND CLINICAL RELEVANCE

Dorsal wire, ventral transarticular pin, and augmented ventral transarticular pin fixation increased rigidity, compared with results for AAJs with intact ligaments and for AAJs with experimentally created instability. Additional studies are needed to assess long-term stability of AAJs stabilized with these techniques.

Restricted access
in American Journal of Veterinary Research