When fingers or the thumb lock up while bent, the condition is known as trigger finger; causes of the condition include repeated or forceful movements, gout, diabetes and rheumatoid arthritis, notes WebMD. Holding something firmly in a set position for a long time also causes joints to lock up.
Musicians, manufacturing workers and farmers often develop locked joints because they make the same thumb and finger movements over and over, explains WebMD. The repeated use of a lighter can cause trigger finger in smokers. Women are more likely than men to develop this condition, and the age group most at risk is between 40 and 60 years of age.
One of the earliest symptoms of trigger finger is discomfort at the base of the thumb or finger, according to WebMD. When a person bends or straightens the finger, a painful snapping or clicking can occur, accompanied by a catching feeling. Rest makes the catching sensation worse, while movement tends to loosen up the joint. When the thumb or finger locks, either straight or bent, it is necessary to straighten it gently with the other hand. Doctors perform a physical exam of the fingers and hand, and in some cases, swelling and a bump near the joint appear as well.