1. Palmar lip # lead to Dorsal sublaxation - volar plate impaction
    1. stability of reduction & percent of #
      1. stable & less than 30% #
        1. stable in extension
        2. Stable in Hyper-extension Swan neck deformity
      2. tenuous=weak & Thin & 30-50%#
        1. stable if PIP is flexed at less than 30 degree
      3. Unstable & more than 50%
        1. stable if PIP is flexed MORE than 30 degree
  2. Dorsal lip # lead to palmar sublaxation - Central slip impaction - stability is Always assessed in extension
    1. STABLE in PIP extension
    2. UNstable = volar displaced (aka palmar translation) of middle phalanx
  3. pilon= volar & dorsal lip fracture - volar plate and central slip impaction