Thumb hypoplasia is usually part of the radial dysplasia spectrum and accounts for about 5% of congenital hand anomalies. Management is determined by the type of displasia and associated syndromes or anomalies.
Aplasia is treated by index pollicization.
Floating thumb, or pouce flottant, is usually managed by amputation and index pollicization late in the first year.
Short thumb in children may be associated with a variety of syndromes. If the shortening is excessive and interferes with function, consider performing a lengthening osteotomy, or deepening the web space. Tailor correction to facilitate function.
Adducted–abducted thumb deformities with shortening require tailored reconstruction that includes both soft tissue and bony reconstruction.
Congenital Clasped Thumb
This deformity is part of the spectrum that often includes a congenital absence of the extensor tendon combined with intrinsic tightness of the thumb. Correct between 3 and 6 months of age with serial casting. If this fails, operative reconstruction is necessary.
Thumb duplications are radial or preaxial and are common. Thumb polydactyly can also be further classified by the pattern of deformity into seven types. Type IV is most common. Types I–VI are usually unilateral, sporatic, and most common in boys. Type VII may be inherited, is often bilateral. Treatment involves reconstruction of all bony and soft tissue elements, to preserve a stable, well-aligned, and functional thumb.
Trigger thumbs are secondary to an acquired nodular enlargement of a segment of the flexor tendon. Large nodules usually become wedged at the pulley, causing the digit to lock in flexion. Smaller nodules pass through the pulley, producing a snapping sensation. Initially manage by observation. If the snapping or locking persists, consider operative release of the flexor A1 pulley. The release decompresses the nodule and allows the thumb to flex and extend freely.