characterized by PIP flexion and DIP extension.
Diagnosis is made clinically with PIP flexion and DIP extension of a digit with presence of a positive Elson test.
Treatment of acute injuries involves splinting of the PIP joint with operative management reserved for chronic, symptomatic injuries.
common in rheumatoid patients
Up to 50% of patients with rheumatoid arthritis develop a boutonniere deformity in at least one digit
caused by rupture of the central slip over PIP joint from
laceration traumatic avulsion (jammed finger) capsular distension in rheumatoid arthritis
pathoanatomic sequence includes
rupture of central slip
attenuation of triangular
palmar migration of collateral bands and lateral bands
injury involves all three phalanges
the middle phalanx flexes on the proximal phalanx at the PIP joint
the distal phalanx is hyperextended relative to the middle phalanx at the DIP joint
refers to PIP joint flexion contracture in the absence of DIP extension
causes the extrinsic extension mechanism from the EDC to be lost
prevents extension at the PIP joint
causes intrinsic muscles of the hand (lumbricals) to act as flexors at the PIP joint