Trigger Finger & Trigger Thumb: Ultrasound-Guided Injection Treatment

Trigger finger, stenosing flexor tenosynovitis, is one of the most common hand problems I treat. It causes pain, clicking or catching at the base of a finger or thumb, and in more advanced cases the digit locks in a bent position and has to be straightened with the other hand. When the thumb is affected it's called trigger thumb. Many people improve with simple measures or a single corticosteroid injection; for those who don't, minimally invasive ultrasound-guided release or open surgery reliably resolves it. This page explains how I assess trigger finger and how I choose between splinting, injection and release.

What is trigger finger?

The tendons that bend your fingers run through a series of fibrous tunnels called pulleys, which hold the tendon close to the bone so it glides smoothly. The one that matters here is the A1 pulley, sitting right at the base of the finger, around the level of the knuckle in the palm.

Trigger finger isn't simply an inflamed tendon. It's a mechanical mismatch: the A1 pulley thickens and the tendon (or a nodule on it) becomes enlarged, so the tendon no longer slides freely beneath the pulley. It catches as it passes through, producing the clicking, pain and locking. In practice it's a combination of a thickened pulley, a swollen or nodular tendon, impaired gliding and, in some people, secondary inflammation.

What are the symptoms?

• Pain and tenderness at the base of the finger or thumb, over the A1 pulley
• Clicking or snapping as you bend and straighten the digit
• Stiffness, often worst first thing in the morning
• A sensation of the finger catching, then intermittent locking in a bent position
• Needing the other hand to straighten it in more advanced cases
• Reduced grip and difficulty with everyday tasks

Early on you may have pain and stiffness without obvious locking. I find it helps to grade severity, because it guides treatment: mild (pain and tenderness, little or no clicking), moderate (clear clicking or intermittent locking, but you can still actively straighten the digit), advanced (locks and needs the other hand to release it), and fixed (won't fully straighten because of persistent locking or a joint contracture). A fixed contracture is the least likely to settle with splinting or injection alone.

Is trigger thumb different?

In adults, trigger thumb and trigger finger share the same basic problem, restriction of the flexor tendon beneath the A1 pulley, and the treatment pathway is broadly the same. The key difference is anatomical: the digital nerves and arteries run close to the thumb's A1 pulley, and the anatomy is less predictable, so blind percutaneous release of the thumb carries a particular concern about injuring those structures. This is exactly where ultrasound earns its place. Splinting and corticosteroid injection remain appropriate; percutaneous release should only be considered with careful imaging and the right expertise; and open release remains a reliable fallback.

Who develops trigger finger?

It's more common in middle-aged and older adults, and more common in women. It can affect one or several digits, and it's associated with diabetes, inflammatory arthritis such as rheumatoid, carpal tunnel syndrome, thyroid disease, and repetitive or forceful hand use. Diabetes is particularly relevant: people with diabetes may have several affected digits, more stubborn symptoms and a less predictable response to injection, but it certainly doesn't mean an injection can't work.

How I assess & diagnose it

Trigger finger is usually a clinical diagnosis. I look at where the pain is, tenderness over the A1 pulley, whether there's clicking or locking on active movement, whether the digit fully bends and straightens, and whether a fixed contracture has developed, while ruling out other causes such as osteoarthritis, Dupuytren's disease, a pulley or tendon injury, or inflammatory tenosynovitis.

Ultrasound isn't essential for every straightforward case, but it adds a lot when things are uncertain. It can show A1-pulley thickening, tendon enlargement or a nodule, fluid or synovial thickening around the tendon, and, with colour Doppler, increased blood flow that signals active inflammation. Crucially, dynamic scanning lets me watch the tendon glide as you bend and straighten the finger, pinpointing the exact moment it catches.

I'm especially likely to scan when the diagnosis is uncertain, symptoms are atypical, there's been previous surgery or injection, the digit is locked, or when I'm planning an image-guided injection or percutaneous release.

Treatment: a stepwise approach

Treatment escalates only as far as it needs to. Broadly:

1. Activity modification and short-term splinting for mild cases
2. Ultrasound-guided corticosteroid injection, the main non-surgical treatment
3. A second injection where the first helped but didn't last
4. Ultrasound-guided percutaneous A1-pulley release
5. Open surgical release for advanced, contracted or complex cases

Splinting & activity modification

Mild cases often improve by easing off aggravating gripping, brief ergonomic changes, tendon-gliding exercises and a short course of splinting, usually a splint that blocks the knuckle (MCP) joint to reduce repeated movement of the tendon under the pulley, sometimes worn at night. A 2023 randomised trial comparing splinting, injection and both found no clinically important long-term difference between them, which makes splinting a reasonable first option when symptoms are mild, there's no fixed locking, and you'd rather avoid an injection (Atthakomol et al., 2023; Lunsford et al., 2019). It's less suitable once the digit is genuinely locking.

Does a corticosteroid injection work?

A corticosteroid injection is the most established non-surgical treatment for adult trigger finger and thumb. The steroid is placed around the flexor tendon and A1 pulley (never into the tendon itself) to reduce swelling and inflammation and restore gliding. Success rates vary widely between studies because they measure different things, but large series report resolution after a single injection somewhere between roughly 49% and 84%, and a recent systematic review of randomised trials confirms injection reliably improves pain and function (Lewis et al., 2023; Kuper et al., 2026). Trigger thumb tends to do particularly well. The honest message I give patients: an injection has a good chance of settling things, but it isn't guaranteed to be permanent.

Why ultrasound-guided injection?

Experienced clinicians get good results using surface landmarks, so not everyone needs imaging. But ultrasound guidance lets me see the A1 pulley and tendon directly, confirm the needle sits around the sheath rather than in the tendon, and steer well clear of the nerves and vessels, which matters most in the thumb. A 2023 study found ultrasound-guided injection gave faster early improvement and an earlier return to work than landmark-guided injection, and a randomised trial showed accurate placement just outside the sheath works as well as inside it (Tunçez et al., 2023; Mardani-Kivi et al., 2018). For those reasons it's my default, especially for the thumb, uncertain anatomy or a previously treated digit.

Can the injection be repeated?

Yes, a second injection is reasonable when the first gave clear but incomplete relief, or worked well and then wore off. A long-term study found around 39% of second and third injections produced lasting success, and about half of people having repeat injections got at least a further year of relief (Dardas et al., 2017). So I'll usually offer a second injection rather than jump straight to surgery. What I won't do is keep injecting indefinitely: repeated short-lived responses are a signal to move on to release rather than continue stacking up steroid.

Ultrasound-guided percutaneous release

Percutaneous release divides the tight A1 pulley through a tiny skin puncture using a needle or a small specialised instrument, no formal incision, freeing the tendon to glide again. It's done under local anaesthetic, tendon movement is tested immediately, and recovery is quick. Doing it under ultrasound means I can watch the pulley, the tendon, the instrument and the nearby nerves and vessels throughout, and confirm the pulley is fully divided. A 2024 systematic review and meta-analysis found ultrasound-guided percutaneous release safe and effective, with favourable recovery and satisfaction compared with non-guided technique (García et al., 2024).

Compared with injection, release is more definitive, it physically corrects the mechanical problem rather than calming inflammation, but it carries the procedural risks of dividing the pulley (incomplete release, or injury to the tendon or a nerve). It's a strong option when injections have failed, the problem keeps coming back, or you'd prefer a more definitive minimally invasive treatment.

Open surgical release

Open release divides the A1 pulley through a small incision in the palm or thumb base, under direct vision. I'd steer towards open surgery when the anatomy is complex, there's a severe fixed contracture, previous treatment or surgery complicates things, or direct visualisation is simply safer. Head-to-head, open and percutaneous release come out very similar: a 2026 meta-analysis of randomised trials found both effective, with percutaneous release giving faster functional recovery and earlier return to activities at comparable safety (Huang et al., 2026). Open release has a high success rate and low recurrence; a Cochrane review found surgery probably produces fewer recurrences than injection, at the cost of more pain in the first postoperative week (Fiorini et al., 2018).

When do I recommend injection, and when release?

I generally recommend an ultrasound-guided corticosteroid injection when the diagnosis is clear, pain/clicking/locking is affecting daily life, the digit is still actively correctable (not fixed), and you'd like to avoid or postpone surgery. Injection can be an initial active treatment, you don't have to complete weeks of splinting first, and it's most likely to succeed when symptoms are mild-to-moderate, relatively recent, in a single digit, without a fixed contracture, and you haven't already had several unsuccessful injections.

I lean towards early release (percutaneous or open) when the digit is persistently locked or developing a fixed contracture, symptoms are severe and mechanically disabling, one or two accurate injections have failed or given only very brief relief, or you'd prefer a more definitive fix. A severely locked digit shouldn't be repeatedly forced straight, that just aggravates it.

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