Which findings on radiography are characteristic of rheumatoid arthritis (RA) in the hands?

Updated: Mar 28, 2019
  • Author: Ian Y Y Tsou, MBBS, FRCR; Chief Editor: Felix S Chew, MD, MBA, MEd  more...
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Answer

Answer

Usually, the earliest sign of RA is a periarticular soft-tissue swelling with a fusiform appearance. Normal fat planes may be obliterated, which occurs as a result of joint effusion, edema, and tenosynovitis. Juxta-articular osteopenia is another early sign, particularly during the acute inflammatory stage. Osteopenia subsequently becomes more generalized as the disease progresses. [7] See the images below.

Soft-tissue swelling and early erosions in the pro Soft-tissue swelling and early erosions in the proximal interphalangeal joints in a patient with rheumatoid arthritis of the hands.
Prominent juxta-articular osteopenia in all interp Prominent juxta-articular osteopenia in all interphalangeal joints in a patient with rheumatoid arthritis of the hands.

Initially, joint spaces in the small joints of the hands show widening as a result of effusion; however, with cartilage destruction, joint spaces narrow. Erosions usually begin at the bare area of the joint not covered by cartilage, such as the intracapsular articular margins. Marginal erosions occur as a result of direct mechanical action of the hypertrophied synovium and granulation tissue. See the images below.

Well-defined bony erosions in the carpal bones and Well-defined bony erosions in the carpal bones and metacarpal bases in a patient with rheumatoid arthritis of the hands.
Multiple erosions with deformity of the carpal bon Multiple erosions with deformity of the carpal bones in a patient with rheumatoid arthritis of the hands.
Follow-up radiograph obtained after an 18-month in Follow-up radiograph obtained after an 18-month interval in a patient with rheumatoid arthritis of the hands. Ankylosis of the carpal bones has occurred, with enlargement of the erosions.

The forces of tendon imbalance and capsular contraction result in joint subluxation and malalignment. Characteristic appearances include the boutonnière (flexion at the PIP joint and extension at the DIP joint) and swan-neck (extension at the PIP joint and flexion at the DIP joint) deformities at the IP joints. Ulnar deviation is also commonly present at the MCP joints. MCP joints may also dislocate and have overriding ends (main en lorgnette or telescoping joints). Subluxations are progressive and may occur with or without the presence of bony erosions. Tendinous involvement of RA may result in rupture of the tendon, causing increased disability. If significant involvement of the scapholunate joint is present, laxity or rupture may cause rotatory subluxation of the scaphoid. See the images below.

Subluxation in the metacarpophalangeal joints, wit Subluxation in the metacarpophalangeal joints, with ulnar deviation, in a patient with rheumatoid arthritis of the hands.
Subluxation at the third metacarpophalangeal joint Subluxation at the third metacarpophalangeal joint and marginal erosions at the heads of the second to fourth metacarpals in a patient with rheumatoid arthritis of the hands.

Fusion or joint ankylosis is common in the later stages of RA. Fusion usually takes place in a deformed or malaligned position. This further reduces the functionality of the hand and affects independence in the activities of daily living. In the end stages, extensive erosions may combine to result in resorption and tapering of the ends of the bones. See the images below.

Marked ankylosis of most of the carpal bones in a Marked ankylosis of most of the carpal bones in a patient with rheumatoid arthritis of the hands.
Partial collapse of fused carpal bones with sublux Partial collapse of fused carpal bones with subluxation at the radiocarpal joint in a patient with rheumatoid arthritis of the hands.

Complications of therapy may be seen, such as generalized osteoporosis from steroid usage. Large bony erosions and severe osteopenia predispose patients to relatively atraumatic fractures. Long-term steroid use also predisposes patients to avascular necrosis.


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