RESEARCH - Evaluation of lateral instability of the atlanto-axial joint in RA using dynamic open-wouth view radiographs

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Clin Rheumatol. 2008 Jul;27(7):851-7. Epub 2007 Dec 18.

Evaluation of lateral instability of the atlanto-axial joint in

rheumatoid arthritis using dynamic open-mouth view radiographs.

Taniguchi D, Tokunaga D, Hase H, Mikami Y, Hojo T, Ikeda T, Oda R,

Takatori R, Imai K, Kida Y, Otakara E, Ito H, Nishimura T, Kubo T.

Department of Orthopaedics, Graduate School of Medical Science, Kyoto

Prefectural University of Medicine, Kawaramachi-Hirokoji, Kamigyo,

Kyoto 602-8566, Japan.

Upper cervical involvement is common in patients with rheumatoid

arthritis (RA). Anterior atlanto-axial subluxation (aAAS) sometimes

occurs at an early stage of the disease. We hypothesized that not only

antero-posterior instability but lateral instability may occur with

atlanto-axial involvement in RA. To prove this hypothesis, we

evaluated the lateral instability of the atlanto-axial joint in RA,

using dynamic open-mouth view radiographs. Thirty RA patients and a

control group of 22 non-RA outpatients were enrolled in this study.

The patients underwent lateral view radiographs of the cervical spine

during flexion and extension, and antero-posterior (AP) open-mouth

views during maximum right and left bending of the neck. The anterior

atlanto-dental interval (AADI) was measured to evaluate

antero-posterior instability of the atlanto-axial joint, and

atlanto-dental lateral shift (ADLS) was defined to evaluate dynamic

lateral instability. In the RA group, AADI averaged 3.2 mm in flexion,

and in eight patients, it exceeded 3 mm in flexion (aAAS). In the

control group, the AADI averaged 1.0 mm in flexion. The ADLS in the RA

group averaged 14.8%, and this was significantly greater than in the

control group, in which it averaged 6.1%. The ADLS averaged 20.6% in

the RA subgroup with aAAS, and 12.7% in the RA subgroup without aAAS.

In both subgroups, the ADLS was significantly greater than that of the

control group. In this study, dynamic lateral instability of the

atlanto-axial joint in RA was demonstrated. The results suggest that

an evaluation of the dynamic lateral instability of the atlanto-axial

joint can be useful for early diagnosis of atlanto-axial lesions in

RA.

PMID: 18087762

http://www.ncbi.nlm.nih.gov/pubmed/18087762

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