Cutting knife finger: if bending the finger is difficult

A jackknife finger is caused by a narrowing of the tendon sheath, making it impossible to straighten or bend the finger. In the initial stages, the finger will still be able to straighten from a bent position, but then a faltering in the form of a kind of click or snap will be noticeable. It is also called a trigger finger and it can lead to annoying obstacles in daily life. What exactly does this condition mean and what can be done about it?

What is it exactly?

Jackknife finger, also called trigger finger, is a condition that gradually develops, making it difficult to straighten or bend the finger. There is a narrowing of the tendon sheath, for example due to a thickened tendon, which makes bending and stretching difficult. If you go through the resistance, the tendon thickening will continue, causing the finger to stretch or bend with a halting movement. The hitch can be felt as a kind of shock, snap or snap. It can occur in one or more fingers, even in both hands, and is more common in women than men. Especially if you spend a lot of time with your hands, it can be quite annoying.


In the beginning you will notice that the affected finger becomes stiff and you hear a snapping sound when you move the finger. Sometimes a lump can be felt in the palm of the hand on the underside of the affected finger. If the tendon sheath narrows further, the finger may become trapped for a moment while bending or stretching and then snap through with a click. The complaints gradually worsen and eventually the finger can even become completely locked in a bent position. This condition is most common in the ring finger, middle finger and thumb. The complaints are usually worse in the morning than during the day.


The fingers contain many tendons that allow you to move them well. There is a layer around the tendon under which there is a greasy liquid substance, which allows the tendon to move smoothly. As a result of overuse, an accident or a rheumatic condition, the space in the sheath that envelops the tendon can narrow, making movement more difficult. If this narrowing becomes too large, there comes a time when the tendon becomes stuck and no longer slides. More force is needed to move the finger. Ultimately, the narrowing is so large that the tendon is stuck.


If you have the aforementioned complaints, it is best to go to the doctor. The sooner it is discovered, the better it is for recovery. The diagnosis of this condition is made based on the patient’s complaints and physical examination.


Determining the best treatment depends on what stage this condition is at. If it is not yet serious, rest of the affected hand will usually be advised. Because the cause is often due to overload, it is often a good idea to give the tendons in the hand some rest for a while so that the narrowing disappears again. Sometimes light exercises are recommended, massaging the finger or immersing it in warm water. This can ensure that the patient continues to be able to move the fingers. If a finger needs to be better immobilized, it can be secured with a splint. This prevents the finger from getting stuck in a bent position during sleep at night. If rest does not help, you can also opt for corticosteroid injections. If other treatments do not help, you can opt to treat the tendon surgically. In that case the tendon sheath will be incised.

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