Trigger finger (stenosing tenosynovitis)

Trigger finger is a condition in which a bent finger does not straighten smoothly but snaps out with a distinct and often painful click. Sometimes it sticks in the bent position for a second or two and can only be straightened with the other hand. The cause lies not in the joint, as people usually assume, but in the flexor tendon and the narrow tunnel it slides through. It is a benign and fairly common problem that responds well to treatment, though it certainly does not always settle on its own.

What it looks like

It usually begins not with the click but with pain and a firm thickening at the base of the finger on the palm side, right where the finger meets the palm. The spot is tender to press, and a firm pea-sized nodule can often be felt under the skin, moving along with the tendon as the finger bends.

Then the characteristic stiffness appears: the finger bends easily but straightens with a delay and a click. It is worst first thing in the morning — after a night's rest the finger sticks the most, and as the day goes on and the hand loosens up, the clicking becomes less frequent. The thumb, ring finger and middle finger are affected most often; several fingers and both hands may be involved.

Left alone, the picture usually worsens slowly: the click becomes more painful and, in advanced cases, the finger becomes permanently fixed in flexion and stops straightening altogether. That is why "it will sort itself out" works less well here than it seems.

Why the finger jams

The flexor tendons run from the forearm muscles to the finger bones through narrow tunnels, held against the bone by ring-shaped ligaments called pulleys. Normally the tendon glides freely inside that tunnel, like a cable inside its sheath.

In this condition the tendon sheath and the entrance to the tunnel thicken, the tunnel narrows, and a small spindle-shaped swelling — a nodule — forms on the tendon itself. While the finger bends, the nodule slips through the narrowed ring; on straightening it catches and only passes back with a jerk. That moment is felt as the click, and sometimes as a temporary lock.

Inflammation here is more a consequence of the mechanical problem than its cause, so anti-inflammatory tablets may take the edge off the pain, but they do not widen the tunnel and do not stop the jamming.

Who gets it more often

An exact cause usually cannot be named, but it is well known who gets trigger finger more often: women, people over forty, and anyone whose work or hobby involves a firm grip held for long periods — workshop and garden tools, secateurs, a steering wheel, a guitar neck, long shifts with the hand clenched.

Diabetes and thyroid disease deserve a separate mention. In diabetes trigger finger develops several times more often, frequently in more than one finger and in both hands, and it is worth knowing this in advance for a very practical reason: in people with diabetes steroid injections work less well and for less time, and the likelihood of eventually needing surgery is higher. One more point: an injection can push blood glucose up for a few days, so it is sensible to test more often over that period and to tell the doctor about the diabetes before the procedure. With an underactive thyroid the link is the same — the problem is commoner and responds less well until the hypothyroidism itself is corrected.

Other conditions in which trigger finger appears more often include rheumatoid arthritis, gout, amyloidosis, carpal tunnel syndrome, Dupuytren's contracture, and a past injury to the base of the finger or the palm.

What you can do yourself: rest and a splint

In mild cases, when it all started recently and the clicking is not yet constant, simple measures are often enough. The main one is removing the load that provokes it: for a few weeks, stop the particular movement that set it off, whether that is daily work with a tool, carrying a heavy bag on bent fingers, or strength exercises with a hard grip. Complete inactivity is neither necessary nor helpful; this is about one specific load.

The second thing that genuinely helps is a night splint. A small splint holds the finger straight during sleep and takes away the morning locking, which is what most often brings people to the doctor in the first place. It is usually worn for several weeks; during the day the finger is moved as normal, with gentle bending and straightening exercises added.

Non-steroidal anti-inflammatory medicines may reduce the pain, but they do not act on the mechanism, so they should not be relied on as treatment. Heat, massage at the base of the finger and rubbing will not stop the clicking; and forcing the finger to "work through it" by yanking it straight only irritates the tendon further, so that should be avoided.

Injection and surgery

If rest and a splint have not helped, or the picture is already well established, the next step is a corticosteroid injection into the tendon sheath. The doctor places a small amount of the medicine right at the tunnel at the base of the finger. The effect is not immediate: sometimes within a few days, more often after two or three weeks. This injection helps most people, and in many cases a single one is enough for a long time. If symptoms return the injection is sometimes repeated, but a second one usually works less well than the first, and they are not given indefinitely. The risks are small: most commonly pain over the first few days, less often lightening or thinning of the skin at the injection site, and very rarely infection.

When injections have not worked, their effect lasts an ever shorter time, or the finger is already fixed, a small operation is offered — dividing that narrowed pulley, after which the tendon glides freely again. It is done as a day case under local anaesthetic and takes only minutes; the finger can be moved straight away, the dressing comes off after a few days, and ordinary activities resume within a couple of weeks. Heavy physical work takes longer, usually about a month. The result is lasting and it is rare for the same finger to lock again. Like any operation it carries risks: a tender scar, temporary stiffness, infection and, very rarely, damage to a small nerve. In rheumatoid arthritis the approach is decided separately, as the standard division of the pulley is not always suitable.

When it is not trigger finger, and when not to wait

Similar complaints occur in other conditions, which are managed quite differently:

• Dupuytren's contracture — the finger is gradually pulled towards the palm by a firm cord that can be felt under the skin; there is no click and no snap, the finger simply stops straightening fully, and often there is no pain at all;
• De Quervain's tenosynovitis — pain along the edge of the wrist at the base of the thumb, worse when the hand is bent sideways, with no locking of the finger;
• osteoarthritis or arthritis of the finger joints — pain and stiffness in the joint itself with swelling all around it, rather than a nodule at the base of the finger in the palm.

Do not put off seeing a doctor, and be seen the same day, if:

• the finger is stuck in the bent position and will not straighten at all, even with help from the other hand;
• there is redness, marked swelling, redness spreading up the finger or hand, or a temperature — this can be how an infection around the tendon shows itself, and it needs urgent care rather than watching;
• it all started after an injury, a cut or a bite, particularly if the finger will not straighten or straightens only partly;
• the finger becomes numb, pale or cold.

Online consultation

Trigger finger is a subject that lends itself well to being sorted out remotely. The diagnosis rests on what you describe and on a simple examination; scans and blood tests are not usually needed for it. In an online consultation the doctor will ask exactly how the finger behaves, distinguish trigger finger from Dupuytren's contracture and De Quervain's tenosynovitis, advise which splint you need and how to wear it, and help you judge whether it is time to discuss an injection or already surgery.

It is also worth getting in touch if you have diabetes or an underactive thyroid: it makes sense to check at the same time how well controlled they are, since that has a direct bearing on how well treatment will work. If the description does not fit an ordinary trigger finger, or any of the warning signs above are present, the doctor will say so plainly and arrange a face-to-face appointment.

This material is for information only and does not replace medical advice.