Fig. 1.

a Photograph demonstrating Wassel-Flatt type IV preaxial polydactyly in the left hand of a 16-month-old male. Note the divergence of the radial and ulnar thumbs at the metacarpophalangeal joint and the convergence at the interphalangeal joints. The radial thumb is notably smaller with poorly formed creases along the dorsal aspect of the interphalangeal joint suggesting more limited motion in comparison with the ulnar thumb. Observation of the child demonstrated preferential use of the ulnar thumb. b Photograph demonstrating postaxial polydactyly in the right hand of an 18-month-old female. In this case, the extra digit is well-formed, and there is a bony connection between the ulnar and radial small fingers. In the majority of postaxial polydactyly cases, the supernumerary digit contains primarily soft-tissue elements and is connected to the hand by a thin cutaneous bridge