Musculoskeletal ImagingRheumatoid arthritis
a joint disease characterized by involvement of
synovial and cartilaginous joints, bursae,
tendon sheaths, entheses, tendons, ligaments, soft tissues and bones. Similar features are found in the
seronegative spondyloarthropathies (
Reiters syndrome,
ankylosing spondylitis and
psoriatic arthritis), but the distribution and extent of abnormalities differ.
Synovitis and hyperaemia are two early radiographic signs of rheumatoid arthritis. Cartilage destruction promoted by components in the rheumatoid synovial fluids may become widespread and severe, sometimes manifested as joint space loss. Two alterations in the subchondral bone that occur in the early stages of rheumatoid arthritis are osteoporosis and marginal erosion.
Bursae and tendon sheaths show similar inflammation (bursitis and tenosynovitis) with soft tissue swelling. In some cases cartilaginous joints and entheses also show abnormalities. "Spontaneous" tendon ruptures are also a known manifestation of rheumatoid arthritis. Rheumatoid nodules represent the most frequent soft tissue lesion in rheumatoid arthritis. Synovial cysts are commonly seen, as is generalized or periarticular osteoporosis. Osteoporosis causes bone weakening and contributes to the fractures (insufficiency fractures) commonly encountered in patients with rheumatoid arthritis.
Although in most cases diagnosis of rheumatoid arthritis is generally made without difficulty, some persons have atypical clinical and radiological features. As a consequence, certain diagnostic criteria have been proposed (Table 1).
Rheumatoid arthritis, Table 1. Diagnostic criteria for rheumatoid arthritis.
| Morning stiffness in and around joints lasting at least 1 hour before maximal improvement |
| Soft tissue swelling (arthritis) of three or more joint areas observed by a physician |
| Swelling (arthritis) of the proximal interphalangeal, metacarpophalangeal or wrist joints |
| Symmetric swelling (arthritis) |
| Presence of Rheumatoid nodules |
| Presence of rheumatoid factor |
| Radiographic erosions with or without periarticular ostoepenia, in hand or wrist joints, or in both |
Rheumatoid arthritis is defined by the presence of four or more of the foregoing criteria.
On radiographs, evaluation of the hands, wrists and feet is important; however, what constitutes the proper projections in each of these anatomic regions is not agreed.
Other diagnostic techniques include fine-detail radiography with magnification, which allows identification of subtle abnormalities; low kilovolt radiography or xeroradiography, which may be used for analysis of soft tissues; arthrography, especially for evaluation of rotator cuff disruption, synovial cysts and sinus tracts; scintigraphy; CT scanning, to assess the hip for acetabular protrusion and the spine for abnormalities; and MR imaging, for detection of and assessment of the activity of articular disease, determination of the nature of some of the complications of rheumatoid arthritis, and analysis of the extent of articular and para-articular changes in specific locations.
DR