Duplicated thumb.

A follow-up study was made of 77 hands for 6 months or more after operation for bifid thumb. Repair of detached thenar muscles and capsule is the most important procedure at the initial ablation of the extra digit. After reinsertion of the thenar muscles, the remaining problems are deformity of bones themselves, adduction contracture in the web space of thumb, hypoplasia of the thenar muscles, and partial or total lack of soft tissues of the thumb. Some technical improvements to obtain a good result are discussed.