Polydactyly is one of the most common congenital anomaly of the hand. Among the polydactyly deformities, duplicated thumb, namely preaxial polydactyly is most frequently occuring. The incidence of polydactyly is generally considered to be 1 per 10,000 live births.
The principal goal of correction of preaxial polydactyly is the accurate establishment of the longitudinal skeletal axis so to maintain adequate opposition & flexion of thumb. However the simple removal of extradigit results in functional or cosmetic deformities, particulary angulation or rotational deformity and joint instability. Therefore it is essential to narrow the widened proximal articular surface, reconstruct collateral ligaments, transfer the insertion site of intrinsic muscle and centralize the extrinsic flexor and extensor tendons at the time of extradigit removal.
Late angular deformity and instability may require further ligament reconstruction, corrective osteotomy and release of skin contracture by Z-plasty or rotation skin flap.
Authors experienced 9 cases of secondary angulation deformity of the preaxial polydactylies. The secondary deformities were corrected by ostectomy, reconstruction of collateral ligaments and soft tissue release using Z-plasties with good functional and aesthetic results.