Some parents unintentionally notice that the interphalangeal joint of their child’s thumb is flexed and cannot be straightened. When the thumb is broken with force, it can sometimes be straightened, often with a popping sensation. However, soon afterwards, the child’s thumb flexes again and returns to its old state. Parents wonder: What is wrong with the child’s hand and what is it? The scientific name for this disease is stenosing tenosynovitis, also known as “trigger finger”. The main manifestation is flexion of the interphalangeal joint of the thumb, which cannot be straightened. Some children can straighten it on their own, or with the help of their parents, but it often returns to its original state soon afterwards. Is this a natural condition or is it caused by trauma? There is no clear cause for this condition. Some believe it is congenital, while others believe it is an acquired nodular enlargement secondary to a flexor tendon. It has been found at birth or at the age of three. Do I need an X-ray or other tests? The diagnosis is usually based on the clinical presentation of the thumb and does not require an x-ray. Will the disease heal on its own? If it does not heal on its own, do I need surgery? It has been reported that 30% of newborns and about 12% of patients between the ages of 6 months and 3 years heal spontaneously, and that surgical treatment before the age of 3 years is satisfactory. In practice, early detection of this disease many parents will first try conservative treatment in the hope that their child will heal spontaneously. In most cases, after weeks or months, the child’s thumb flexion never gets better or gets progressively worse and some activities that require thumb flexion and extension are affected, then surgery is eventually needed. What does the surgery look like and can it recur? Surgery is performed by making a small incision on the palmar aspect of the metacarpophalangeal joint, exposing the narrow tendon sheath and cutting it longitudinally to restore flexion and extension of the thumb. Since the cause of this disease is unknown, there is a risk of recurrence after surgery. However, if the patient insists on passive exercise after surgery, avoids tendon sheath adhesions, and follows up regularly, there is little chance of recurrence.