A cystic protrusion of the wrist is one of the symptoms of a tendon sheath cyst. A tendon sheath cyst (thecal cyst) is the most common type of mass on the dorsal side of the wrist and can also occur on joint capsules and tendon sheaths in other parts of the body. Causes of thecal cysts: 1. Modern medicine believes that tendon sheath cysts are caused by factors such as local degeneration within the connective tissue. Most people now believe that tendon sheath cysts are due to degenerative changes in the connective tissue on the joint capsule, ligaments, and tendon sheath due to local malnutrition and the formation of cysts. Some cases are related to trauma. 2, Chinese medicine believes that trauma or strain injures the hand Shaoyang Sanjiao meridian, causing dysfunction of transportation and transformation; or injures the fascia, causing stagnation of qi and blood. No matter the derangement of transportation or stagnation of qi and blood, it can lead to the accumulation of water and fluid in the meridians of the bones, thus forming cysts. 3.Western medicine believes that this disease is mostly related to chronic strain, mechanical stimulation and trauma to the joint or tendon sheath, while Chinese medicine believes that tendon sheath cysts are caused by trauma to the fascia, evil qi resides, stagnation and poor transportation and fluid accumulation in the bone meridians. Mostly due to excessive activities of the affected joints, repeated weight-bearing, standing for a long time, etc., strain the tendons, resulting in the poor flow of qi and fluid and stagnation of tendons and veins. So the treatment of tendon sheath cyst is currently the most used or for the cause of tendon sheath cyst tendon sheath paste is very good to activate the stasis. 4, Chinese medicine believes that this disease is trauma to the fascia, the evil dwelling, stagnant transport and transformation is not smooth, water accumulation in the bone meridians and become. Mostly due to excessive activity of the affected joints, repeated weight-bearing, standing for a long time, etc., strain the tendons, resulting in the poor operation of Qi and fluid, stagnation of tendons and veins. 5.The examination can feel a round mass with smooth shape and clear boundary, and the surface skin can be pushed without adhesions. Most of the cysts have higher tension, tough masses and a few are soft, but all of them are cystic in nature. Ultrasound examination can help to determine the nature of the mass.