Bone, Joint and Muscle Conditions

Trigger Thumb

What Is Trigger Thumb?

Trigger Thumb

Your child's trigger thumb may lock in a bent position.

Trigger thumb means your child's thumb pops, clicks or catches when they try to straighten it. Their thumb may lock in a bent position. If the thumb locks, your child can pull it straight using their other hand. (Or you can pull it straight for them.) But they can't straighten the locked thumb using their thumb muscles.

The muscle that bends the tip of the thumb is called flexor pollicis longus (FLEX-er PAHL-i-sis LONG-us). This muscle starts in your child's forearm. Near the wrist, the muscle turns into tendon. The tendon runs along the palm side of your child's thumb and connects to the bone in the tip of the thumb.

When your child moves their thumb, this tendon should glide smoothly inside a wrapping called a tendon sheath. Near the base of the thumb, a tough band (ligament) crosses the tendon and tendon sheath, acting like a pulley. Doctors call this the A1 pulley.

Trigger thumb occurs when the tendon swells, forming a bump (nodule) near the A1 pulley. The nodule gets stuck at the pulley, so the tendon cannot glide inside the sheath. You may be able to feel this bump on your child's palm at the base of their thumb.

Trigger Thumb in Children

In children, trigger thumb usually happens between the ages of 1 and 3 years old. It's not thought to be due to injury or other medical problems.

Most children with trigger thumb have it in only one hand. About one-third of children have it in both hands. Triggering can happen in fingers, too. This is a different and more complex problem.

Trigger Thumb at Seattle Children's

Trigger thumb is one of the most common conditions treated by the experts in our Hand and Upper Extremity Program. Each year we see many children with this condition in our clinics.

Our team is well versed in the treatment options for trigger thumb. For many children, treatment begins with stretching and splinting. This may be enough to cure the problem. If it's not, we perform surgery to release the A1 pulley. Our surgeons are experienced at performing this type of surgery in children.