Adult Rheumatoid Arthritis


KEY FACTS

Imaging

  • Erosions of dens, uncovertebral joints, facet joints

  • Atlantoaxial instability in 20-86% patients with rheumatoid arthritis (RA)

  • Atlantoaxial subluxation in 5% of cervical RA

  • Cranial settling occurs in 5-8% of RA patients

  • Lower cervical spine: Facet and uncovertebral joint erosions, instability

  • Neutral, flexion, and extension lateral radiographs performed for evaluation of instability

    • Normal: 2 mm between inner margin anterior ring of C1 and dens

    • High correlation to neurologic symptoms with distance ≥ 9 mm

  • Pannus is mass-like and surrounds and erodes dens, facet joints, uncovertebral joints

    • Low signal on T1WI

    • Heterogeneous signal on T2WI, STIR

    • Enhances avidly with gadolinium

Top Differential Diagnoses

  • Seronegative spondyloarthropathy

  • Calcium pyrophosphate dihydrate deposition (CPPD) disease

  • Juvenile chronic arthritis

  • Osteoarthritis

  • Degenerative disc disease

Clinical Issues

  • 50-60% of RA patients have involvement of cervical spine

  • Never involves spine before hands &/or feet

  • May develop radiculopathy, myelopathy

  • Instability → significant morbidity, mortality

Diagnostic Checklist

  • Calcifying mass with odontoid erosions is not RA

    • Indicates crystalline arthropathy, usually CPPD

Axial and sagittal graphics show erosion of dens by hypertrophied synovial tissue (pannus). The pannus has eroded the transverse ligament of the dens , resulting in instability. The spinal cord is compressed.

Coronal CT reconstruction illustrates erosive changes at the right C1-C2 joint and lateral subluxation of C1 with respect to C2 . Inflammatory synovial proliferation and destruction of surrounding bone also affect the uncovertebral joints in the subaxial spine .

Lateral view from a bone scan shows focal marked uptake at the C1-C2 junction in this patient with rheumatoid arthritis (RA).

Sagittal NECT scan shows upward translocation of the odontoid and widened atlantodental interval . The skull and C1 have remained together with the ligamentous laxity and disruption at C1-C2 (coupled with the C1 lateral mass collapse), allowing C2 to migrate cephalad into the foramen magnum with brainstem compression (not shown).

TERMINOLOGY

Abbreviations

  • Rheumatoid arthritis (RA)

IMAGING

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