What is wrong with my child’s thumb? Some parents may occasionally find that their child’s thumb cannot be straightened, or that it can be straightened after massage but soon gets stuck again. It turns out that the child has a popping thumb. It is a common condition in children, because the affected finger is flexed like a trigger and has a popping sound, also known as “trigger finger”, also known as “congenital stenosing tenosynovitis”, which is a congenital disease unique to infants and children. As the flexor tendon is located at the distal end of the metacarpophalangeal joint, the tendon is narrowed by the narrow fibrous lesion of the tendon sheath, causing the proximal tendon to thicken or become nodular, causing the interphalangeal joint to be in a flexed position, unable to actively straighten, and causing pain or popping sounds when passively extended. In children with popping fingers, the symptoms do not appear at birth, but are commonly seen at the age of 6 months to 2 years when the fingers are flexed and cannot be straightened, with the most common sites being the metacarpophalangeal joints of the thumb, second and third fingers, where a round, raised nodule can be palpated with light pressure pain and a popping sensation when extending and flexing, while the interphalangeal joints are fixed in flexion and have a popping sensation when moving and extending. However, it is often not taken seriously by parents and is not seen until the age of about 2 years or even older. This leads to severe finger deformation and dysfunction of the infant thumb, which has a significant impact on the long-term hand function of the child. Because thumb function accounts for 40% of total hand function, patients with congenital stenosing tenosynovitis of the infant thumb who present with clinical signs of strangulation or popping indicate that there is no possibility of self-healing and should be treated with early surgery to avoid affecting the function and development of the child’s thumb. Surgery is generally appropriate for treatment within two years of age. The surgery is performed under direct vision to completely release the narrow tendon sheath and restore the normal movement of the thumb, while effectively avoiding damage to the blood vessels and nerves. The postoperative period needs to be accompanied by strengthening functional exercises with good results.