Tenosynovitis is the inflammation of the fluid-filled sheath (synovium) that surrounds a tendon. The inflammation is usually caused by a microtrauma or stress, and mostly affects people with physical jobs. The abductor muscle and the short extensor in the thumb are usually affected by the inflammation which can thicken the ligament and damage the sheath (synovium).
- De Quervain syndrome
This unusual disease causes soreness and swelling in the wrist besides also causing cysts and nodules. The affected part of the wrist is the extensor ligament of the thumb which is responsible for moving the thumbs up and outwards. The syndrome will thicken your ligament up to twice its size and make any wrist movement extremely painful.