duplication of the metacarpal
Last reviewed 01/2018
Partial or complete duplication of the duplicated thumb metacarpal and all distal bones encompasses groups 5 and 6 in the Wassel classification. At this level, a number of considerations are relevant:
- the ulnar metacarpal is usually dominant but C-shaped (a delta bone); this may require a corrective osteotomy
- thenar muscles need to be transferred from the discarded digit to the remaining digit
- the first web may be tight and require release
- if the ulnar digit is too ulnar on the trapezium, it can be translocated to the retained base of the radial thumb metacarpal to give a better axis for function