Trigger finger: the digit that clicks, catches, and locks
Last updated September 3, 2026.
Trigger finger (stenosing tenosynovitis) is a finger or thumb that catches, clicks, or locks when bent: the tendon that flexes the digit sticks in its sheath at the palm, then releases with a snap. It favors the ring finger and thumb, it is commoner with diabetes and repetitive gripping, and it is one of the most fixable hand problems there is: a steroid injection cures most, and a ten-minute procedure cures the rest.
What does it feel like?
The progression: first stiffness and a tender nodule at the base of the finger (in the palm), then clicking or catching as the finger bends (worse in the morning), then the dramatic version: the finger locks in a bent position and either releases with a painful snap or has to be straightened with the other hand. Gripping hurts; shaking hands hurts; the locked finger is alarming but not dangerous. It can affect several digits, and both hands. The clicking is the tendon squeezing through a too-tight tunnel: mechanical, visible, and oddly satisfying to demonstrate.
Why does it happen?
The flexor tendon (running through a sheath with pulleys at the palm) develops a swollen section or the pulley thickens: the swollen tendon sticks at the pulley mouth, then pops through. The associations: diabetes (a strong one), underactive thyroid, repetitive gripping work, carpal tunnel syndrome, rheumatoid arthritis, gout, and middle age, with women affected more. It is mechanical: no amount of rest for the rest of the body fixes a tight pulley, which is why the treatments target the tunnel directly.
What actually fixes it?
- Steroid injection: the first-line fix: a corticosteroid injection into the tendon sheath at the palm, curing the majority (around 60-90%, best in early cases and non-diabetics), sometimes needing a second shot.
- Splinting and rest: a splint holding the finger straight (especially overnight) and easing off the gripping: helps mild cases and buys time, less definitive.
- Percutaneous or open release: the ten-minute definitive fix: dividing the tight pulley under local anesthetic (by needle or a small cut), with success rates above 95% and immediate freeing.
- The diabetes wrinkle: injections work less reliably and sugar spikes briefly afterward; releases are commoner in this group.
- Hand therapy: exercises after injection or surgery to restore glide and grip.
When is it an emergency?
Trigger finger never is. The reasons for a different assessment: a hot, red, swollen, very painful finger or palm (infection: same-day, especially after an injection), a finger locked and unmovable with significant pain (prompt clinic review), numbness in the digit, and a lump growing at the base rather than a nodule (other diagnoses). A digit locked for weeks untreated can stiffen permanently, which is the argument for acting rather than adapting. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
Why does my finger lock? What is physically happening?
The mechanics are visible and oddly satisfying to understand: the tendon that bends your finger runs through a tunnel (a sheath with a pulley at the palm), and when a section of tendon swells or the pulley thickens, the swollen part sticks at the tunnel mouth as you bend; with enough force it pops through (the click), and when it cannot pop back, the finger locks bent until the other hand forces it. The tender lump you feel at the base of the finger is the swollen tendon section itself. Nothing torn, nothing broken: it is a size-mismatch problem between tendon and tunnel, which is why the fixes (shrinking the swelling with steroid, or widening the tunnel surgically) are so reliably effective.
How well does the steroid injection work, and what does it involve?
It is the workhorse: a corticosteroid injection into the tendon sheath at the palm (a few seconds of sharpish discomfort, sometimes with local anesthetic), working over days to a couple of weeks, and curing the majority of trigger fingers: figures run roughly 60-90%, best in early, mild, single digits, and lower (though still worthwhile) with diabetes and long-standing locking. A second injection is the standard move if the first partially works. The cautions: a brief blood-sugar rise in diabetics, slight skin thinning or depigmentation at the site, a small infection risk (the reason a hot red painful hand afterward is same-day), and recurrence is possible, at which point the release procedure awaits.
What is the release procedure like?
One of the most satisfying minor operations in medicine: under local anesthetic, in about ten minutes, the tight pulley at the palm is divided, either through a small open cut or percutaneously (with a needle tip through a pinhole), freeing the tendon instantly (patients often test the finger on the table and feel it glide). Success rates exceed 95%, recurrence is rare, and recovery is quick (a small dressing, hand use as comfort allows, stitches out at about ten days for the open version, grip back over a few weeks). The rare risks (infection, nerve irritation, scar tenderness) are small against a locked finger. It is the definitive answer when injections fail or locking is established.
Why is it worse in the morning?
The overnight mechanics: during sleep the fingers rest bent and still, the swollen tendon parks against the tight pulley, and fluid shifts thicken the tissues, so the first movements of the day are the stickiest and most painful; as the hand warms and moves, the tendon glides more freely and the clicking fades to its daytime level. The splint logic follows directly: a night splint holding the finger straight parks the tendon in the open position, reducing the morning lock-up and giving the inflamed section hours of rest, which is why night splinting is the standard conservative measure alongside or before the injection. Morning stiffness easing through the day is typical and expected.
Is it connected to my diabetes?
Yes, genuinely: diabetes is one of the strongest associates of trigger finger (and of the related hand conditions: carpal tunnel, frozen shoulder, Dupuytren's), with higher rates, more multiple digits, and somewhat less reliable injection responses; the mechanism is the glucose-related thickening of tendon and connective tissue over years. The practical sequels: mention new hand symptoms early (the diabetic hand benefits from acting sooner), expect the possibility of the release procedure rather than repeated injections if response is partial, watch your sugars for a few days after any steroid shot, and know that better long-term glucose control is genuinely protective for tendons: this is one of the places diabetes shows up that people are never warned about.
Will it spread to my other fingers?
Sometimes: trigger finger is often multiple (several digits on one hand, or both hands over time), and the same risk profile that produced the first (diabetes, thyroid, gripping work) tends to produce siblings, so a second digit triggering is a common story rather than a spreading disease. Each digit is treated on its own merits (each responds to its own injection or release), and having one treated successfully says nothing ominous about the others: it just predicts you will recognize the next one instantly. The genuinely useful habit: at the first clicking stage (before locking), the splint-plus-injection response is fastest and most reliable, so do not wait for the lock.