It is one of the most common hand surgical diseases, which mainly manifests as soreness and pain on the palmar side of the metacarpophalangeal joint during the flexion and extension of the fingers, and in severe cases, popping and even locking, resulting in dysfunction of the flexion and extension of the fingers. Although this disease can affect both adults and children, its causes and treatment methods are different. The cause of pediatric flexor tenosynovitis, also known as congenital stenosing tenosynovitis, is an abnormal thickening of the A1 tendon sheath that leads to a narrowing of the sheath and the formation of a hard nodular expansion of the flexor tendon at the proximal end of the A1 tendon sheath, resulting in dysfunctional flexion and extension of the finger. However, it is controversial whether the cause of the disease is congenital or acquired. In adults, the cause of flexor tenosynovitis is more often related to strain on the affected finger, as repeated flexion and extension of the affected finger over a short period of time leads to aseptic inflammatory changes in the tendon sheath tissue, which eventually leads to thickening of the tendon sheath and narrowing of the sheath. Stenotic entrapment can develop. In addition to the above causes, there are also aggravating factors such as cold stimulation, diabetes, peritendinous synovitis, rheumatoid disease, etc. The early manifestations of flexor tenosynovitis are soreness and pain on the palmar side of the metacarpophalangeal joint during finger flexion and extension activities, and in more serious cases, popping and even locking, resulting in dysfunction of finger flexion and extension. These symptoms are more severe in the morning when waking up, and some of the symptoms are reduced in the afternoon, and cold stimulation can often aggravate the symptoms. In pediatric patients, the thumb is most often involved in flexor tenosynovitis, while all fingers can be involved in adults. On physical examination, pressure pain at the level of the A1 carriage can be seen, and in some patients, a hard nodular enlargement can be palpated near the A1 carriage, which can slide back and forth with the flexor tendon during finger flexion and extension. In more severe cases, the affected finger may show a fixed flexion deformity (strangulation), and both active and passive extension may be limited. The diagnosis of flexor tenosynovitis can usually be confirmed by clinical examination, or in less typical cases by ultrasound. Diagnosis Usually, a clear history of strain, together with progressive flexor soreness, pain, popping and strangulation, can usually establish the diagnosis relatively easily. For atypical cases, ultrasound examination is also feasible to help confirm the diagnosis. Conservative treatment can be effective in adult cases with initial onset. Conservative treatment includes braking the affected finger, avoiding cold stimulation, physical therapy, and using blood-activating, swelling and pain-relieving drugs. For pediatric patients, local massage, straightening the affected finger, with brace fixation and other methods of treatment, it is reported that about 40% of such cases can be cured by conservative treatment. 2, closed treatment can use prednisolone-type preparations with a small amount of local anesthetic injected into the A1 tendon sheath local, in order to play a role in anti-inflammatory, swelling, some patients with significant results, but, after the closure if the strain continues, easy to recur, and closed should not be repeated, repeated injections, because there have been several closed injection cases resulting in tendon rupture reported. In addition, for children patients should not use closed treatment. 3, small needle or thick needle percutaneous release treatment such treatment belongs to a minimally invasive treatment, can be completed in the outpatient clinic, is to use a small needle or thick needle percutaneous cutting, loosening A1 carriage, such operations need experienced doctors to operate, because not under direct vision operation, there is a risk of picking off the tendon, injury to the surrounding nerves, blood vessels. In some children, the radial finger nerve of the thumb crosses the A1 carriage, so the use of small needles or thick needles is not recommended for the treatment of pediatric flexor tenosynovitis. 4.Surgical treatment is feasible if the above treatment is ineffective. Surgery can be performed under direct vision to protect the finger nerve and vascular bundle, and to accurately and completely release the A1 carriage. If the surgery is performed under local anesthesia, the patient can be asked to actively flex the finger to determine the sliding nature of the tendon and whether there is any popping sound. Functional exercises for flexion and extension should be started the day after surgery, otherwise tendon adhesions may easily occur and lead to postoperative finger movement disorders. Prevention There is no clear prevention for pediatric flexor tendonitis. But for adults, flexor tendinitis can be prevented by reducing strain, avoiding cold stimulation, good control of blood sugar (for diabetic patients), early treatment of peritendinous synovitis and rheumatoid etc.