Categories

Trigger Finger: Causes and Risk Factors

Cause

Trigger finger is caused by the inflammation of one of the tendons that run [2] through your fingers. The tendons are thick inelastic fibrous cords that attach the muscles to the bones. They are all surrounded by a protective membrane (sheath). To flex the fingers, long tendons (flexor tendons) that extend from the muscles of the hand slide through the tendon sheath or tunnel and pull the bones. The inflammation of the tendons of the finger causes the affected tendon to slide through the sheath covering it abnormally.

As the tendon sheath becomes more irritated by this motion, it gets inflamed and may develop scarring and thick bumps called nodules. The nodules narrow the tendon tunnel and interfere with the sliding of the tendon. Sometimes this causes the tendons to get trapped within the sheath and leaves the fingers stuck in a bent position. The finger may snap straight like a trigger when the trapped tendon suddenly breaks free and slides through the sheath.

This process is what results in the condition known as trigger finger, but the precise cause of the condition is not known. It is thought that several factors contribute to it. These risk factors are explored in the next section.