What is the pathology of rheumatoid arthritis (RA) of the wrist?

Updated: Jan 11, 2019
  • Author: Michael Neumeister, MD, FRCSC, FACS; Chief Editor: Joseph A Molnar, MD, PhD, FACS  more...
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Answer

Answer

Pathology of RA of the wrist is somewhat predictable and usually follows a progressive pattern. The ulnar side of the wrist is most commonly affected with synovitis that destroys the ulnar carpal stabilizing ligaments. The triangular fibrocartilage complex (TFCC) is attenuated, and the distal radial ulnar joint becomes eroded as the dorsal capsule is disrupted. The proliferative synovitis results in dorsal subluxation of the distal ulna, volar subluxation of the extensor carpi ulnaris tendon, and supination of the proximal carpal bones. These signs are collectively known as caput ulna syndrome.

Destructive synovitis at the radial side of the wrist results in (1) attenuation of the radioscaphocapitate ligament with rotary subluxation of the scaphoid and (2) ulnar translocation of the carpal bones. The carpal height collapses, and bony destruction of the wrist ensues. Clinically, the hand deviates radially and maintains a supinated position. This imbalance causes ulnar drift of the phalanges on the metacarpals as the extrinsic forces of the extensors and flexors pull the fingers into this position. Therefore, the pathology of the wrist promotes distal finger deformity. Correction of the wrist pathology before correction of the fingers is often prudent to prevent recurrences of the finger deformities.


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