Thumb/first web classification

Cole and Manske described a classification system for ulnar dysplasia that is based on the morphology of the thumb and first web space:

• type A: normal
• B:
  • narrow first web
  • mild thumb deficiency
  • extrinsic tendons intact
  • opposition present
• C:
  • syndactyly of thumb to index
  • hypoplastic thumb malrotated into plane of palm
  • lack of opposition
  • lack of extrinsic extensor function
• D: absent thumb

Ref: Cole RJ, Manske PR (1997); J Hand Surg (Am); 22(3): 479-488.