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HealthInfo Canterbury

What is trigger finger?

Trigger FingerA trigger finger affects the tendons that bend the finger. In a trigger finger the finger becomes locked after it has been bent (flexed). It is difficult to straighten and sometimes you need to pull it with the other hand. You may hear a click when it is pulled straight. It may be sore and you may feel a snap when it is bent (flexed). One or more fingers may be affected.

There are different grades of trigger finger. A mild trigger finger may be painless, and you might be able to straighten it just by paying attention to how it feels, and hearing it "catch". If it is very severe it can be sore and lock, so that you can't straighten it, even using your other hand.

It is usually worse in the morning and gets better over the day. Certain activities can make it happen more.

It is generally just called trigger finger, but the medical name for it is stenosing flexor tenosynovitis.

What causes it?

We often don't know exactly what causes trigger finger. It involves one of your tendons, the strong tissue that attaches a muscle to a bone. When you bend or straighten your finger the tendon slides through a tunnel at the bottom of your finger, called a tendon sheath, which keeps the tendon in place. Inflammation or irritation means part of the tendon swells (creating a nodule). It then can't slide through the tunnel and catches instead.

In some cases it happens after heavy use of your hand, such as repetitive screwdriving, or using tools that press on the palm, such as secateurs. These may cause some inflammation.

Women and people aged over 40 are more likely to get trigger finger. It is also more common if you have certain diseases, such as rheumatoid arthritis, amyloidosis, diabetes or carpal tunnel syndrome, or if you are on dialysis. However, most people with trigger finger do not have any of these conditions.

How is it diagnosed?

A doctor will diagnose trigger finger talking to you and examining your hand. You probably won't need any other tests.

On the next page: Living with trigger finger

Written by HealthInfo clinical advisers. Endorsed by clinical director, Plastic Surgery, Canterbury DHB. Updated January 2017.

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