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Year |
2001 |
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Question Number |
87 |
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Category |
Select |
Question
Flexion-extension radiographs of an adult patient with long-standing rheumatoid arthritis have shown C1-2 instability of 6mm for the past several years. Current flexion-extension radiographs now show the C1-2 atlanto-dens interval to be fixed at 5mm (there is no motion on flexion-extension). What is the most likely explanation for this finding?
1. the arthritis has stabilized
2. the c1-2 joint has fused
3. the patient ahs been wearing a cervical collar
4. medical advancements have been made in the management of arthritis
5. Basilar impression (atlantoaxial impaction) has developed
Figures
Answer (click for answer)
The correct answer is 5. The article that was sited traces natural course of cervical spine lesions in 49 patients with RA. They were able to identify the following progressive pattern of the upper cervical subluxation: Stage 0: no radiographic evidence of subluxation; Stage 1:generation of atlanto-axial subluxation (AAS). Stage 2:generation of vertical subluxation (VS) associated with preceding AAS. For the generation of AAS, rheumatoid involvement of central atlantoaxial joint and the resultant insufficiency of the transverse or the alar ligaments were supposed to occur. Fixation of AAS, which meant a decrease of anterior ADI, was also observed in this study. It was actually a sign of the start of VS. Its pathomechanism was supposed to be a destruction of atlantoaxial facet joints
Reference: Spine 1995; 20:1128-1135