Trigger finger (also known as stenosing tenosynovitis) is a condition that affects the tendons in your fingers or thumb, causing them to become inflamed and thickened. This can lead to difficulty in straightening or bending the affected finger, often resulting in it "locking" or "catching" in a bent position, like a trigger being pulled and released. It is difficult to straighten out without pulling on it by the other hand. When the finger "snaps" back into place, it can be painful.
This is a companion discussion topic for the original article at https://patient.info/bones-joints-muscles/tendinopathy-and-tenosynovitis-tendinosis/trigger-finger