Trigger finger or trigger thumb is a common wear-and-tear condition, which causes the digit to lock in a bent position.
Patients with diabetes and rheumatoid arthritis are more prone to it.
The tendon in the affected finger snags in the sheath (tube in which it is supposed to glide). This happens at the mouth of the tube, which is situated just at the crease of the palm.
The tendon starts to tear slightly like a frayed rope at this site and a nodule develops. The collar at the start of this tube also becomes thickened and inflamed so you have a tight ring around a slightly degenerate tendon with a lump on it.
Patients get a clicking sensation in their finger or thumb and it may lock in the closed position. It can be very painful to straighten out, and as it does so there is a click.
Gripping tends to make the finger get stuck, so patients naturally try to avoid bending it in the first place. As a result, hand function rapidly declines, which makes everyday activities such as washing, dressing and driving a struggle.
This is a progressive disease. In the early stages it is just a clicking sensation that you can overcome by finger movement. In the second stage patients have to use their other hand to straighten the digit, and in the final stage it won’t straighten at all (Fig. 1). Occasionally the digit locks straight and cannot be easily bent.
The symptoms are worst first thing in the morning because we don’t bend our fingers much in our sleep. Finger movement disperses the natural lubricant – synovial fluid- in the tube, without this the finger is more prone to seize up.