Trigger finger is a condition affecting the movement of the tendons as they bend the fingers or thumb toward the palm of the hand. This movement is called flexion. The tendons that move the fingers are held in place on the bones by a series of ligaments called pulleys. These ligaments form an arch on the surface of the bone that creates a sort of tunnel for the tendon to run in along the bone. To keep the tendons moving smoothly under the ligaments, the tendons are wrapped in a slippery coating called tenosynovium. The tenosynovium reduces the friction and allows the flexor tendons to glide through the tunnel formed by the pulleys as the hand is used to grasp objects.
Triggering is usually the result of a thickening in the tendon that forms a nodule, or knob. The pulley ligament may thicken as well. The constant irritation from the tendon repeatedly sliding through the pulley causes the tendon to swell in this area and create the nodule.
Rheumatoid arthritis, partial tendon lacerations, repeated trauma from pistol gripped power tools, or long hours grasping a steering wheel can cause triggering. Infection or damage to the synovium causes a rounded swelling (nodule) to form in the tendon. Triggering can also be caused by a congenital defect that forms a nodule in the tendon. The condition is not usually noticeable until infants begin to use their 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 it gets stuck at the near edge. The nodule cannot move back through the tunnel, and the finger is locked in the flexed trigger position.
Treatment is provided by a hand physiotherapist may be effective when triggering has been present for less than four months. Therapists often build a splint to hold and rest the inflamed area. Special exercises are used to encourage normal gliding of the tendon. You might be shown ways to change your activities to prevent triggering and to give the inflamed area a chance to heal.
A steroid injection into the tendon sheath may be needed to decrease the inflammation and shrink the nodule. This can help relieve the triggering, but the results may be short lived. A splint may be used after the injection to rest the tendon and help decrease the inflammation and shrink the nodule.
The usual solution for treating a trigger digit is a trigger finger release operation to open the pulley that is obstructing the nodule and keeping the tendon from sliding smoothly. This surgery can usually be done as an day case procedure, meaning you can leave the hospital the same day.