Rheumatoid arthritis, partial tendon lacerations, repeated trauma from pistol gripped power tools, or long hours grasping a steering wheel can cause triggering. Triggering can also be caused by a congenital defect that forms a nodule in the tendon. The condition is not usually noticeable until the infant begins to use its hands. The symptoms of trigger finger or thumb include pain and a funny clicking sensation when the finger or thumb is bent. Pain usually occurs when the finger or thumb is bent and straightened.
Tenderness usually occurs over the area of the nodule - at the bottom of the finger or thumb.
The clicking sensation occurs when the nodule moves through the tunnel formed by the pulley ligaments. With the finger straight, the nodule is at the far edge of the surrounding ligament. When the finger is flexed, the nodule passes under the ligament and causes the clicking sensation. If the nodule becomes too large it may pass under the ligament, but becomes stuck at the near edge. The nodule cannot move back through the tunnel and the finger is locked in the flexed trigger position.