RESEARCH - Is RA a risk factor for a high-riding vetebral artery?

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Spine. 2008 Aug 15;33(18):2007-11.

Is rheumatoid arthritis a risk factor for a high-riding vertebral artery?

Miyata M, Neo M, Ito H, Yoshida M, Miyaki K, Fujibayashi S, Nakayama

T, Nakamura T.

Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto

University, Kyoto, Japan.

STUDY DESIGN: A retrospective comparative study on the morphologic

characteristics of the axis in patients with or without rheumatoid

arthritis (RA). OBJECTIVE: To compare the morphologic risk of

vertebral artery (VA) injury during atlantoaxial transarticular screw

fixation between patients with or without RA.

SUMMARY OF BACKGROUND DATA: VA injury is a potentially serious

complication during atlantoaxial transarticular screw fixation.

Although this operation is frequently performed on RA patients, there

have been few comparative studies on the morphologic risk of VA injury

between RA and non-RA patients.

METHODS: A total of 107 three-dimensional computed tomography images

of the cervical spine including the C1-C2 complex were evaluated.

Forty-seven RA patients and 60 non-RA patients were included in the

study. The maximum atlantoaxial transarticular screw diameter (MSD)

that could be inserted without breaching the cortex was measured

3-dimensionally using a computer- assisted navigation system. A

high-riding-VA carrier was defined as a patient with either MSD of 4

mm or less. In RA patients, the space available for the spinal cord in

flexion (SAC in flexion), duration of disease, RA stage, and type of

disease were examined.

RESULTS: In the RA group, 45 of 94 MSDs (47.9%) were 4 mm or less, and

33 of 47 patients (70.2%) were high-riding-VA carriers. In the non-RA

group, 11 of 120 MSDs (9.2%) were 4 mm or less, and 9 of 60 (15.0%)

patients were high-riding-VA carriers. MSD, C3 A-P diameter, and the

ratio of MSD to C3 A-P diameter were significantly smaller in the RA

group than in the non-RA group. Multiple logistic regression analysis

showed that SAC in flexion was a significant risk factor for a

high-riding-VA carrier in the RA group.

CONCLUSION: RA was a significant risk factor for the presence of a

high-riding VA. When performing atlantoaxial transarticular screw

fixation, particularly on RA patients, thorough preoperative

evaluation of the bony architecture is of great importance to avoid

inadvertent VA injury.

PMID: 18708934

http://www.ncbi.nlm.nih.gov/pubmed/18708934

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