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Question 5#

Hypoplastic thumbs Type II of the Blauth classification can be treated successfully by:

A. Releasing the contracted first web space, reconstruction of the ulnar collateral ligament, transposition flap to release the first web space, a full thickness skin graft and opponensplasty
B. Releasing the contracted first web space, reconstruction of the radial collateral ligament, transposition flap to release the first web space, a full thickness skin graft and opponensplasty
C. Amputation of the hypoplastic thumb and pollicisation of the index finger with use of a full thickness skin graft
D. Amputation of the hypoplastic thumb and pollicisation of the small finger with a split thickness skin graft
E. Amputation of the hypoplastic thumb and a toe-to-hand transfer

Correct Answer is A

Comment:

Releasing the contracted first web space, reconstruction of the ulnar collateral ligament, transposition flap to release the first web space, a full thickness skin graft and opponensplasty. In hypoplasia of the thumb, Blauth Type 2, the thumb is smaller and less stable than normal. The hypoplasia has three elements: 1) adduction contracture of the first web space is apparent because of 2) the lack of thenar muscles, and the hand compensates by exhibiting 3) laxity of the ulnar collateral ligament that allows abduction of the MCP joint. The skeleton, although small, has normal articulations. Treatment of this condition requires: a) release of the first web space using a dorsal flap from the thumb - preferably, as described by Strauch, and closing the thumb defect with a full thickness skin graft; b) reconstruction of the ulnar collateral ligament, as described by Lister using the division of the flexor digitorum superficialis (FDS) that is utilized for c) an opponensplasty, as described by Royle. There are other methods for soft tissue release, ligament reconstruction and opponensplasty, but this is the simplest and probably the least invasive while reducing morbidity of donor sites.

References:

1. Strauch B. Dorsal thumb flap for release of adduction contracture of the first web space. Bull Hosp Joint Dis 1975; 36(1): 34-9.
2. Lister G. The hand: diagnosis and indications, 2nd ed. London, UK: Churchill Livingstone; 1984: 312-51.
3. Royle ND. An operation for paralysis of the intrinsic muscles of the thumb. JAMA 1938; 111: 612.