Eaton classification of volar plate avulsion injury

The Eaton classification was proposed by Eaton and Malerich in 1980, and presently (time of writing, August 2016) along with Keifhaber-Stern classification, is the most widely accepted classificationof volar plate avulsion injuries .

Knowledge of the orthopedic Eaton classification is practical when reporting volar plate injury of the PIP joint as it influences the decision on management. Treatment is dependent on the following factors:

  • size of the fragment (<40% of the articular segment)
  • degree of impaction
  • direction of the dislocation
Eaton types
  • Eaton type I: hyperextension mechanism of injury with an avulsion of the volar plate and a longitudinal tear of the collateral ligaments; the opposing joint surface remain congruent
  • Eaton type II: dorsal dislocation of the PIP joint with avulsion of the volar plate; there is complete tear of the collateral ligament
  • Eaton type III
    • Eaton type IIIa
      • fracture dislocation with an avulsed small fragment <40% of the articular surface
      • dorsal aspect of the collateral ligament remains attached to the middle phalanx
    • Eaton type IIIb
      • fracture dislocation with fracture or impaction of the articular surface of more than 40%
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