Trigger finger, or trigger thumb, is a type of stenosing tenosynovitis in which the sheath around a tendon in a thumb or finger becomes swollen, or a nodule forms on the tendon. In either case, the tendon can no longer slide freely through its sheath. Affected digits may become painful to straighten once bent, and may make a soft crackling sound when moved. More than one finger may be affected at a time, though it usually affects the thumb, middle, or ring finger. The triggering is usually more pronounced in the morning, or while gripping an object firmly.
It is called trigger finger because when the finger unlocks, it pops back suddenly, as if releasing a trigger on a gun.
The two mainstays of treatment are 1.corticosteroid injection directly around the tendon and sheath and 2. surgical release of the sheath.
One or two corticosteroid injections resolve the problem more than 50% of the time, and may be slightly less effective in diabetics.  It is unusual to give more than 2 or 3 corticosteroid injections, primarily because too many injections can weaken local tissues and can cause skin atrophy and discoloration. Injections work by reducing the size of the nodule on the tendon and this can take weeks to months.
Operative treatment provides more rapid and predictable relief, but is most often used when corticosteroid injections are unsuccessful. The problem is resolved by a relatively simple surgical procedure (usually outpatient, under local anesthesia). The surgeon will cut the sheath that is restricting the tendon.
Dupuytren's contracture is a disorder of the skin and underlying tissue on the palm side of the hand. Thick, scar-like tissue forms under the skin of the palm and may extend into the fingers, pulling them toward the palm and restricting motion. The condition usually develops in mid-life and has no known cause (though it has a tendency to run in families).
Surgery is the only treatment for Dupuytren's contracture. The surgeon will cut and separate the bands of thickened tissue, freeing the tendons and allowing better finger movement. The operation must be done very precisely, since the nerves that supply the hand and fingers are often tightly bound up in the abnormal tissue. In some cases, skin grafts are also needed to replace tightened and puckered skin.
The results of the surgery will depend on the severity of the condition. You can usually expect significant improvement in function, particularly after physical therapy (see Recovery and rehabilitation.), and a thin, fairly inconspicuous scar.