Thick thumbs may be related to congenital structural growth and developmental abnormalities, bone and joint diseases, trauma and so on. 1. Abnormal growth and development of congenital structure: Due to abnormal growth and development of congenital structure of the thumb, the bone develops abnormally in the process of growth, which leads to the situation that the patient has a big thumb. 2. Bone and joint diseases: Bone and joint diseases, such as osteochondroma, bone cyst, etc., can also easily lead to abnormal development of the bone structure of the thumb, thus causing the phenomenon of thumb enlargement. 3. Trauma: after the thumb is hit by external force, the local bone damage will affect the blood circulation, which in turn affects the normal growth and development of the thumb, and then the patient may have the phenomenon of thumb enlargement. There are other reasons for thumb enlargement, we suggest that patients go to the hospital in time to find out the cause of the disease, and then carry out standardized treatment, so as not to delay the condition.