The first cause of tenosynovitis is exogenous, the hand is in a fixed action for a long time, such as often playing the piano, often playing the guitar or typing, doing housework, engaged in an action for a long time, the external force between the tendon and tendon sheath friction, resulting in inflammation. There are some congenital deformities of the tendon sheath. Some scholars believe that tenosynovitis, because of endocrine reasons, is more common in women aged 30-50 years old, and the ratio of men to women is about 1:10, with a much higher incidence in women than in men.