Floating thumb is type IV thumb dysplasia, its most obvious feature is that the first metacarpal bone of the affected hand is completely missing or only remains, so the thumb is floating thumb state, can’t make strength, can only move with the swinging of the hand, the affected hand thumb function is completely lost, the function of the hand is greatly reduced, the child can’t pinch the object, and can’t hold some big objects with force, usually holding objects rely on the index finger, middle finger to clip, there will be a lot of inconvenience in life. Inconvenience. In the past, floating bunions were mainly treated by bunionization, in which the thumb was directly removed and the index finger was moved to the thumb position to be used as the thumb. Although this method allows the child to have the function of the thumb after the operation, many parents find it too cruel and hard to accept. Although the floating thumb does not have a metacarpal bone and cannot be utilized for strength, it still has blood vessels and nerves inside, and can sense heat, cold and pain, so it is not completely useless, so we recommend that it be preserved. There are two surgical options to save the thumb, metatarsal reconstruction and hallux valgus grafting. Metatarsal reconstruction takes a portion of the metatarsal bone from the foot to reconstruct the first metacarpal bone, so there will be a certain amount of bone resorption and necrosis, as well as a certain amount of impact on the foot, which is a concern for some parents since it is an incision on the foot. Semi-metacarpal bone graft reconstruction surgery is a kind of surgical plan to protect the five fingers after metatarsal bone reconstruction technique, taking part of the bone from the second metacarpal bone of the affected hand to reconstruct the first metacarpal bone, so the chance of bone resorption and necrosis is greatly reduced, and the whole surgery is only carried out on the hand, which doesn’t hurt the child’s other parts of the body, and the post-operative care is relatively simple, only need to pay attention to the hand on the line. Semi-metacarpal bone graft reconstruction surgery will be done in two phases, the first phase is mainly to move the bone, so that the thumb can have a better shape, the first phase of the surgery needs to be immobilized for a period of time, and then after the bone healing the second phase of the surgery – rebuild the function of the thumb, so that the thumb can be moved up, the two phases of the surgery is done after the child can start to function exercise, and slowly can do some fine movements, and the child can be able to do some fine movements. After the two surgeries, the child can begin functional exercises, and can slowly perform fine motor skills or grasp large objects with a strong grip, and both form and function will improve significantly.