Two-Stage "On-Top Plasty" for Thumb Polydactyly With a Floating Ulnar Thumb: 3 Case Reports.

We present 3 cases of thumb polydactyly treated with a 2-stage "on-top plasty" technique. For all the 3 cases, the ulnar thumbs floated in the first web with a skin pedicle, and the radial thumbs presented hypoplasia of different degree. We designed a 2-stage "on-top plasty" technique. The first operation included transplantation of the ulnar floating thumb and construction of skin tube containing the neurovascular bundle. When followed up after the first operation, there was no vascular compromise, and all union was achieved. At the time of the second operation, the skin tube was opened up, the neurovascular bundle was transposed to the reconstructed thumb, and the first web plasty was performed. At the final follow-up, 3 cases showed acceptable results both cosmetically and functionally.