A rather irritating form of osteoarthritis, Trigger Finger occurs when the tendon catches, snaps or locks in the affected finger. This is caused by an inflamed or swollen tendon and is most often caused by repetitive or forceful movements of the finger or thumb. Normally treated with a cortisone injection into the tendon, Trigger Finger can also be treated through surgery. Trigger Finger surgery involves cutting the sheath that is restricting the tendon, thereby enabling the tendon to snap easily back into place and not lock.