Coughlin classification

Last revised by Henry Knipe on 27 Oct 2020

The Coughlin classification is the most widely used to type bunionettes. It relies on simple angle measurements on weight-bearing foot radiographs taken in the dorsoplantar projection 1,2. In 2013 DiDomenico et al added type IV 2.


  • type I: enlarged lateral surface of the head of the 5th metatarsal
  • type II
    • irregular lateral bowing of the distal 5th metatarsal
    • 4th to 5th intermetatarsal angle (4-5 IMA) is normal
    • lateral deviation angle is abnormal
  • type III
    • 4th to 5th intermetatarsal angle (4-5 IMA) is abnormal
    • lateral deviation angle is normal
  • type IV: any combination of types I-III

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