Polydactyly is a common deformity in children. After polydactyly removal, although the polydactyly is gone, other deformities may appear. There are several types of deformities as follows: 1. Angular deformity: Due to the scar contracture after polydactyly removal, the end joint of the thumb is pulled to one side, so that the interphalangeal joint is not flat, forming a certain angle of bending, and the thumb cannot be straightened. 2. Interphalangeal joint instability: After surgery, the interphalangeal joint of the thumb can only be flexed and extended, but cannot swing from side to side, so there will be weakness in pinching and unstable pen grip. This is the reason for not repairing the lateral collateral ligament when removing the polydactyly. 3.Bone superfluous formation: The child is young when the polydactyly is removed, so the operation cannot fully remove the polydactyly, leaving a stump or the residual periosteum is gradually ossified when the polydactyly is removed, and as the child grows older, a “recurrent polydactyly” is formed. 4, the appearance of small: If the “twin thumb”, simply remove a finger, leaving the thumb is inevitably smaller than the opposite side, the appearance is very unattractive. 5, “Z” deformity: mainly for the complex type of polydactyly, ignore some fine “process”, so that after the operation, the interphalangeal joint is oblique, like “Z” deformity. deformity. This is the most complicated deformity after polydactylism.