Common deformities of the hand in RA:
Fusiform swelling: synovitis
of PIP joints, causing them to appear spindle-shaped.
Boutonnière deformity: flexion
of the PIP and hyperextension of the DIP joint, caused by weakening of the
central slip of the extrinsic extensor tendon and a palmar displacement of the
lateral bands. This deformity resembles a knuckle being pushed through a
Swan-neck deformity: results
from contraction of the flexors (intrinsic muscles) of the MCPs, resulting in
flexion contracture of the MCP joint, hyperextension of PIP, and flexion of the
Ulnar deviation of fingers:
with subluxation of MCP joints. This results from weakening of the extensor
carpi ulnaris leading to radial deviation of the wrist causing all finger
tendons to pull the fingers ulnarly with power grasp.
hyperextension of IP joint with flexion of MCP and exaggerated adduction of
first metacarpus. Causes inability to pinch.
“Piano key” ulnar head:
secondary to destruction of ulnar collateral ligament leading to a floating
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