Trigger finger or Stenosing Tenosynovitis is a condition in which the affected finger or thumb clicks, catches
or locks, normally in a bent position, although it may occasionally present as an inability to bend. It is caused
by some wear and tear or swelling of the tendon that causes a nodule to form. The tendon runs through a
fibrous tunnel, called the A1 pulley, and much like trying to pull a thread through the eye of a needle when
there is a knot in it, the nodule catches or locks at the mouth of the pulley.
Trigger finger usually occurs without any obvious cause, but is more common in people with diabetes. It can
also be a problem in people with rheumatoid arthritis, but is not caused by osteoarthritis. There is little
evidence that it is caused by working with the hands, but heavy activity, such as manual work, gardening, DIY
etc. can exacerbate the condition.
This diagnosis of trigger finger is usually made on the history (what you tell the doctor) and examination in
clinic. It may very occasionally be necessary to investigate further with x-ray or ultrasound examinations to
ensure the diagnosis is correct.