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Updated: Jan 15 2023

Boutonniere Deformity

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  • Summary
    • Boutonniere Deformities are Zone III extensor tendon injuries 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.
  • EPIDEMIOLOGY
    • Incidence
      • common in rheumatoid patients
        • Up to 50% of patients with rheumatoid arthritis develop a boutonniere deformity in at least one digit
  • Etiology
    • Mechanism 
      • caused by rupture of the central slip over PIP joint from
        • laceration
        • traumatic avulsion (jammed finger)
        • capsular distension in rheumatoid arthritis
    • Pathoanatomy
      • pathoanatomic sequence includes
        • rupture of central slip
          • causes the extrinsic extension mechanism from the EDC to be lost
          • prevents extension at the PIP joint
        • attenuation of triangular ligament
          • causes intrinsic muscles of the hand (lumbricals) to act as flexors at the PIP joint
          • lumbricals also extend the DIP joint without an opposing or balancing force
        • palmar migration of collateral bands and lateral bands
          • the lumbricals' pull becomes unopposed, pulling through the base of the distal phalanx and volar to the PIP
          • causes PIP flexion and DIP extension
      • bone deformity
        • 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
    • Associated conditions
      • rheumatoid arthritis
      • pseudo-boutonniere
        • refers to PIP joint flexion contracture in the absence of DIP extension
  • Anatomy
    • Muscle
      • lumbrical muscles
        • originate from the FDP and insert on the lateral bands
    • Ligament anatomy
      • extensor hood and central slip
        • the extrinsic extensor tendon joins the extensor hood at the MCP
        • the central portion of the extensor hood forms the central slip
        • the central slip inserts onto the middle phalanx and acts to extend the PIP joint
      • lateral bands
        • the lateral bands are formed from the deep head of the dorsal interossei combining with the volar interossei
        • the lateral bands insert onto the base of the distal phalanx to extend the DIP joint
      • triangular ligament
        • spans the two lateral bands, preventing them from subluxing volarly
      • transverse retinacular ligament
        • prevents dorsal subluxation of the lateral bands
    • Blood supply
      • interosseous muscles
        • receive blood from vessels formed by a combination of the deep palmer arch and the ulnar artery
  • Presentation
    • Physical exam
      • deformity
        • characterized by PIP flexion DIP extension
      • Elson test
        • is the most reliable way to diagnose a central slip injury before the deformity is evident
        • bend PIP 90° over edge of a table and extend middle phalanx against resistance.
          • in presence of central slip injury there will be
            • weak PIP extension
            • the DIP will go rigid
          • in absence of central slip injury DIP remains floppy because the extension force is now placed entirely on maintaining extension of the PIP joint; the lateral bands are not activated
  • Imaging
    • Radiographs
      • recommended view
        • radiographs are not required in evaluation and treatment of Boutonniere deformity
  • Treatment
    • Nonoperative
      • splint PIP joint in full extension for 6 weeks
        • indications
          • acute closed injuries (< 4 weeks)
        • technique
          • encourage active DIP extension and flexion in splint to avoid contraction of oblique retinacular ligament
          • complete part-time splinting for an additional 4-6 weeks
    • Operative
      • primary central band repair
        • indications
          • acute displaced avulsion fx (proximal MP avulsion seen on x-ray)
          • open wound that needs I&D
      • lateral band relocation vs. terminal tendon tenotomy vs. tendon reconstruction
        • indications
          • in chronic injuries after FROM is obtained with therapy or surgical release
        • technique
          • terminal tendon tenotomy (modified Fowler or Dolphin tenotomy)(never central slip tenotomy)
          • secondary tendon reconstruction (tendon graft, Littler, Matev)
          • triangular ligament reconstruction
      • PIP arthrodesis
        • indications
          • rheumatoid patients
          • painful, stiff and arthritic PIP joint
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