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HealthInfo Waitaha Canterbury

Trigger thumb

Kōnui keu

A child's trigger thumb is bent in, with the tendon jammed by a nodule stuck at the A1 pulleyWe move our thumb with a tendon that connects a muscle in our forearm to the tip of our thumbs. Near the base of our thumb the tendon runs through a tunnel of tendon, which can be quite thick in places. Doctors call this the A1 pulley.

In trigger thumb, swelling forms a bump (or nodule) near a child's A1 pulley. When the tendon moves, the nodule gets stuck at the A1 pulley and the tendon cannot move any further.

We do not know why this happens in pēpi (babies). It isn't usually there at birth. Often a parent first notices it after their tamaiti (child) has fallen or had an injury and cannot straighten their thumb, but it's likely it was already there.

Symptoms of trigger thumb

If your tamaiti child has a trigger thumb, their thumb will pop, click or catch when they move it, or it will be locked in a bent position.

Trigger thumb is usually painless. But if it gets stuck in a bent position, it can be painful to force it straight. Your tamaiti may have swelling in their thumb (usually near the base) or a bump on the palm of their hand (near the base of their thumb).

Tamariki (children) with trigger thumb can usually use their hands normally. In more than half of cases, their thumb will move freely again without any medical treatment.

Diagnosing trigger thumb

If you suspect your tamaiti has a trigger thumb, it's important to see your GP. They will ask questions about your child's symptoms and examine their hand and fingers. They will also check to make sure they do not have some other problem, like a broken bone or a joint that is out of place (dislocated).

It's unlikely your tamaiti will need other investigation such as X-rays.

Helping my child with trigger thumb

Using splints or taping your child's thumb usually doesn't help.

Taking regular photos of your child's thumb to monitor progress can help. This can show doctors how your child's thumb is progressing. If their thumb becomes locked in a bent position, the photos can help pinpoint when that happened.

If their thumb isn't locked in a bent position (you can straighten it or they can straighten it with their other hand), stretches and massage can help to free the nodule.

To stretch their thumb, apply gentle pressure to the tip of their thumb and try to straighten it.

To massage it, massage at the base of the thumb where you can feel the nodule. Massage can help the tendon to move past the A1 pulley.

Treating trigger thumb

If your child's thumb is still bent when they're 18 months old, they aren't using their hand properly or they say their thumb hurts, they may need to see a plastic or orthopaedic (bone) surgeon.

The surgeon may recommend an operation called a trigger thumb release or an A1 pulley release. This is done as day surgery, so your tamaiti will not need to stay overnight in hospital. The operation is done with a general anaesthetic (meaning your tamaiti will go to sleep) but it's very quick. Your child's surgeon will discuss the risks and benefits of this surgery with you.

The surgeon will make a small cut (incision) in the crease of skin at the base of your child's thumb. Then they will widen the entrance of the tunnel by cutting through (releasing) the AI pulley. This takes pressure off the tendon and allows it to glide smoothly. The surgeon will not cut into the tendon or remove the nodule.

After surgery, your tamaiti will need a bandage for one to two weeks to protect their thumb while it heals. It's important to keep their hand clean and dry during this time to stop them getting an infection.

Trigger thumb is unlikely to come back and your tamaiti probably will not need any other treatment for it. Once they have healed, you can expect your tamaiti to have normal use of their thumb.

Important

After surgery you should take your tamaiti to their GP if you have any concerns or notice any signs of infection. These include:

Also return to your GP if your tamaiti isn't using their hand normally within two weeks of the wound healing and the bandage coming off, or if the trigger thumb comes back.

Written by HealthInfo clinical advisers. Last reviewed May 2022.

Sources

Page reference: 380376

Review key: HIWHC-380375