Wassel Classification (Thumb Polydactyly)
Wassel classification of thumb polydactyly (radial / preaxial thumb duplication) by the most proximal level of skeletal duplication, types I-VII.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Wassel type
- Type IV - duplicated proximal phalanx (most common)
Result: Wassel type IV: duplicated proximal phalanx (the most common type).
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Type I
- Bifid distal phalanx (shared epiphysis).
- Type II
- Duplicated distal phalanx.
- Type III
- Bifid proximal phalanx.
- Type IV
- Duplicated proximal phalanx (most common).
- Type V
- Bifid metacarpal.
- Type VI
- Duplicated metacarpal.
- Type VII
- Triphalangeal thumb.
What you enter
- Wassel type
How this is calculated
Wassel HD. The results of surgery for polydactyly of the thumb: a review. Clin Orthop Relat Res. 1969;64:175-193. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.