A tendon sheath cyst is a cystic swelling that occurs within the tendon sheath of the joint, a condition caused by degeneration of the connective tissue surrounding the joint capsule. It contains a colorless, clear or orange, yellowish, thick mucus. The main clinical feature is a hemispherical elevation on the superficial surface of the skin, which is soft and pushable, mostly on the wrist. It is a slowly developing cystic swelling on the dorsal wrist or dorsal foot, with a spherical shape, smooth surface, clear border, soft texture and fluctuating sensation, no obvious conscious symptoms or slight soreness; when the cystic fluid is full, the cystic wall becomes hard and local pressure is painful. When touched, the subcutaneous is full and has fluctuating cyst-like sensation, accompanied by wrist weakness, discomfort or pain, mostly soreness or radiating pain, and may have certain functional impairment. Treatment of tendon sheath cysts is done by squeezing or pounding to rupture the tendon sheath cysts, which gradually absorb on their own, but may recur after treatment. Those that are connected to the joint cavity do not rupture easily. Or, puncture to extract the cyst fluid and inject adrenocorticotropic hormone or hyaluronidase is used, which is effective. When other methods of treatment are ineffective, the tendon sheath cyst may be surgically removed. Strenuous activity of the affected joint should be avoided for 1 month after surgery. Tendon sheath cysts are more common in females and adolescents and are most likely to occur near the joint or tendon sheath, with the highest incidence in the dorsal wrist, flexor carpal tendon on the palmar side of the wrist and dorsal foot. Chronic injury increases the synovial fluid in the synovial cavity and forms cystic herniation or connective tissue mucosal degeneration as an important cause of morbidity. For people who have been dealing with computers for a long time, holding the mouse for too long or having an incorrect posture can lead to injury to the synovial cavity of the hand joint and cause disease. Do not use the computer for a long time, if you need to surf the Internet for a long time, you should also take a break every hour for 5 to 10 minutes, and do indoor exercises, soft exercises or local massage, stretching and muscle training for the shoulders and neck, upper limbs and wrists to increase flexibility and muscle strength.