Ingrown thumbs are defined as the presence of ingrown thumbs when the child moves his or her hands independently in extension (unconscious movement before 5 months of age, active movement after 5 months of age) and the remaining four fingers in extension. The thumb inversion does not appear as an abnormal posture when the child is in a sleeping state or relaxed. The thumb inversion mainly affects the baby’s fine motor skills after 11 months of age, and has a greater impact on the baby’s button tying and writing. Most children with early thumb inversion can be rehabilitated through rehabilitation training or home training exercises, but if there is a significant increase in muscle tone, they need to be treated with rehabilitation training in hospital. Treatment is not based on drugs, but on rehabilitative training, together with physical therapy (electrotherapy), with drugs as a secondary treatment.