Floating thumb is a type IV thumb dysplasia that clinically presents with a thumb that lacks a metacarpal bone or has only the remains of a metacarpal bone, with a total loss of thumb function and greatly diminished hand function, with great impact on form and function. Why do children develop floating thumb? The cause of floating thumb is unclear. Teratogenic factors include nutritional deficiency, fetal neurogenic injury, maternal viral infection, drug effects, and hypoxia. As to whether there is a genetic factor, further evidence is needed because I have not yet seen any cases where the parents have floating thumb and the child has floating thumb, or where the first child has floating thumb and the second child has floating thumb. If the child has a floating thumb, parents should not worry too much, floating thumb can be corrected through surgery, we are now using the hemipalmar bone graft reconstruction technology, from the second metacarpal bone of the affected hand to take part of the bone to rebuild the first metacarpal bone, so that the thumb first has a better shape, and then after the bone heals, the second stage of surgery to establish the function of the thumb, after two stages of surgery the child can start functional exercise, can After the two stage surgery, the child can start to exercise the function of the thumb, and can slowly hold some things, such as writing, holding chopsticks, and grasping some large objects more powerfully, which can basically meet the needs of daily life.