Tendon sheaths are located near the joints and around the long tendons of the muscles in the hands and feet. Due to the frequent activities in these areas, there are many opportunities for injury. If care is not taken, long-term friction, chronic strain or cold stimulation can cause a sterile inflammatory reaction of the tendon and tendon sheath, with local exudation and edema. The tendon sheath becomes mechanized, the sheath wall becomes thickened, the lumen becomes narrowed, and the tendon becomes restricted in the tendon sheath causing clinical symptoms (pain and dysfunction), which is called tenosynovitis. Pediatric stenosing tenosynovitis of the thumb, also known as trigger finger, is a relatively common pediatric orthopedic disease, most commonly in the thumb, manifested by flexion of the interphalangeal joint, which cannot be straightened. Thickened tendons can be palpated at the metacarpophalangeal joint, such as small swellings, which move with the flexion and extension of the finger and sometimes have pressure pain. Causes Unlike the causes of trigger finger in adults, which are mostly related to strain or metabolic diseases, the causes of pediatric trigger finger deformity are not yet clear, and sometimes there is a family history of genetic disease. It is presumed to be caused by abnormal edema in this area during development. Most scholars now believe it may be due to a congenital narrowing of the tendon sheath of the flexor tendon of the thumb. Over time, the proximal end of the flexor tendon, which is blocked from sliding, becomes hypertrophied and nodular, producing a popping sound when it passes through the narrow tendon sheath, resembling a trigger and giving it its name.