Trigger thumb occurs when a bump exists on the tendon that moves the joint at the tip of the thumb, causing the thumb to jump or “trigger” when it's used. In other cases, the thumb might be locked in a bent position.
What Causes Trigger Thumb?
The tendon that moves the joint at the tip of the thumb is like a strong cord that connects the muscle to the bone. Inside the thumb, the tendon glides inside a tunnel, called the tendon sheath.
For normal movement of the thumb joint, the tendon must slide up and down inside the tendon sheath. If the tendon becomes too thick, it can no longer glide through the sheath normally, and the thumb can trigger or lock.
How Is Trigger Thumb Treated?
Treatment for trigger thumb involves a surgical procedure, called a trigger thumb release, to enlarge the tendon sheath and allow the thumb to move more normally. After the procedure, the child will wear a cast for one to two weeks.