Trigger Finger: Why Does Your Finger Catch or Lock?

It usually shows up first thing in the morning. A finger curls into the palm and stays there, then flicks straight with a painful click, or needs the other hand to straighten it. The name, trigger finger, comes from that sudden release.

Trigger finger sounds dramatic, but the problem is mechanical and small. A tendon has stopped gliding smoothly through a tight tunnel at the base of the finger. Mild cases often settle with changes to grip or a splint. Persistent cases usually respond to an injection, and a minor operation is available for the rest.

Why does the finger catch?

The tendons that bend the fingers run through a series of fibrous loops, called pulleys, that hold them close to the bone. In trigger finger the tendon and the first pulley at the base of the finger no longer slide easily past each other. That causes a tender spot in the palm, a click as the finger moves, or a finger that locks bent.

It is often worse in the morning or after a lot of gripping. Hand use can aggravate it, but that does not mean work, gardening or sport has caused lasting damage. Trigger finger is more common in people with diabetes and can occur with rheumatoid arthritis, though many people have no obvious cause.

The diagnosis is usually made from the history and examination. X-rays and MRI are not routinely needed. Ultrasound can help when the pattern is unclear or another tendon, joint or lump needs to be ruled out.

What can be tried first?

For mild or recent symptoms, the aim is to reduce the repeated painful catching while keeping the hand in use. That can mean easing off forceful or prolonged gripping for a while, moving the finger gently within a comfortable range, and looking at grips on tools, keyboards, gym equipment or garden tools that keep the finger tightly bent for long periods.

A splint worn at night, or one that limits how far the affected joint bends, is worth a defined trial. A review by McKenna and colleagues found splints helped pain and function in the short term, though the studies used different splints and schedules. A hand therapist can choose and fit one without restricting the rest of the hand.

Pain relief can make the hand more comfortable. It does not make the tendon glide more freely. A pharmacist or GP can advise what suits a person’s other medicines and health.

When does an injection help?

A cortisone injection around the tendon sheath is the usual next step when symptoms stay painful or limiting. A meta-analysis of randomised trials by Pathak and colleagues found it worked better than control injections for many people. Success rates vary between studies, and symptoms can return. Diabetes, symptoms that have gone on a long time, several affected fingers and more severe locking all lower the chance of a lasting result.

The injection reduces the swelling around the narrowed pulley so the tendon can move again. Side effects include a pain flare for a day or two, thinning or lightening of the skin at the injection site, a temporary rise in blood sugar in people with diabetes and, rarely, infection or tendon injury. Ultrasound guidance shows the tendon and the structures around it.

When is surgery worth discussing?

Surgery releases the tight pulley so the tendon has more room. It is usually discussed when the finger stays locked, symptoms seriously limit work or daily life, or other treatment has not helped enough.

The operation usually stops the triggering. It still involves recovery, and the possible complications include a tender scar, stiffness, infection, nerve injury and an incomplete release. The decision depends on which finger is affected, how severe it is, other health conditions, previous treatment and what the hand needs to do.

When should a finger be checked sooner?

A finger stuck bent that cannot be straightened, or one that is getting rapidly worse, needs prompt review. A hot, red, swollen finger, fever, a recent cut or bite, or severe pain when someone tries to straighten the finger can mean infection and needs urgent assessment.

Review is also worthwhile after a significant injury, when numbness or weakness comes with the catching, or when several fingers are affected and diabetes or inflammatory arthritis may need attention.

Will it get better?

For the person whose finger locks every morning, the outlook is good. Many mild cases settle with a splint and a change in grip, an injection helps most of the rest, and surgery is there for the few that persist.