In rheumatoid arthritis, which cervical level is most at risk for atlantoaxial subluxation?

• A. C1-C2
• B. C2-C3
• C. C3-C4
• D. C4-C5

Answer: (A)

In rheumatoid arthritis, the upper cervical spine is most vulnerable, especially the atlantoaxial joint between the first two cervical vertebrae. Inflammation in this region often forms pannus that disrupts the transverse ligament, which normally keeps the dens against the anterior arch of the atlas. When this ligament laxity or destruction occurs, the atlas can move forward on the axis (anterior atlantoaxial subluxation). This setup is highly prone to subluxation because the joint is highly mobile, so even small inflammatory changes can cause instability that may compress the spinal cord or brainstem.

That’s why this level is at the greatest risk. The other cervical levels can be involved, especially later in disease, but the atlantoaxial joint is the classic site for subluxation in RA. Clinically, be mindful of neck pain, occipital headaches, and potential neurologic signs, and use dynamic imaging to assess for instability at this level.