Flexion finger is a change in the finger that undergoes flexion deformity, a flexion of the finger, often with a family history, which begins inconspicuously and gradually increases in flexion, often with other systemic syndromes such as Doun syndrome. The diagnosis can be made based on its clinical manifestations and deformity characteristics. Clinical manifestations The main manifestation is shortening of the superficial flexor muscle, the cause of the deformity is unclear, mostly due to irregularities in the starting point of the superficial muscle, which can start from the superficial flexor ring finger muscle or earthworm muscle. It is often accompanied by skin shortening, and the function of finger extension will be limited. Deformity characteristics 1, the flexion deformity often occurs in the little finger, occasionally involving the ring finger, more than half of them are bilateral. 2.The flexion often occurs in the proximal interphalangeal joint, sometimes accompanied by metacarpophalangeal joint or wrist antagonistic dorsal extension. The flexion of the fingers occurs progressively before the age of 10 years, often with a family history, and is not obvious at first, but gradually becomes more severe and is taken seriously by parents. 4, often accompanied by other systemic syndromes such as doun syndrome, klinefelfer syndrome, several common facial syndromes, sometimes accompanied by crooked deformity. The main manifestation is flexor superficial muscle shortening, the cause of the deformity is unclear, mostly due to irregularities in the starting point of the superficial muscle, can start from the flexor ring finger superficial muscle or earthworm muscle, etc.. It is often accompanied by skin shortening, and the function of finger extension will be limited. Finger flexor tenosynovitis is a condition in which the finger cannot be flexed or extended. The main manifestations are limited pain on the palmar side of the metacarpophalangeal joint and limitation of finger movement. As the tendon sheath becomes narrower and the tendon becomes enlarged in a gourd shape after compression, the enlarged portion will be difficult or impossible to slide through the narrowed tendon sheath, and the finger will remain in extension or flexion, resulting in interlocking.