How is tightness of intrinsic muscles due to rheumatoid arthritis (RA) assessed?

Updated: Feb 07, 2020
  • Author: Howard R Smith, MD; Chief Editor: Herbert S Diamond, MD  more...
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Tightness of intrinsic muscles (eg, the interossei and lumbricals) may cause major declines in finger mobility. This tightness is ascertained on examination when the PIP joint cannot be flexed while the MCP joint is fully extended but can be flexed while the MCP is in flexion (Bunnell test); primary PIP joint pathology is evident with the MCP joint in either position. For accurate assessment, the phalanx must be aligned with the metacarpal; when ulnar deviation at the MCP joint exists, the intrinsic muscles on the ulnar side are slack, allowing more motion.

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