(See also Overview of Hand Disorders.)
Pockets of pus (abscesses) may occur around the tendons that run along the inside of the hand and fingers. These tendons are inside a sleeve of tissue called the tendon sheath. The sheath helps the tendons slide smoothly. A tendon sheath abscess is caused by an injury that penetrates one of the creases on the palm side of a finger. Pus from an untreated felon may also spread from the tip of the finger into the end of the tendon sheath. Infection and pus form around the tendon and rapidly destroy tissue. The gliding mechanism of the tendon becomes damaged, so the finger can barely move.
Symptoms of infection of the tendon sheath include swelling and pain of the finger and tenderness over the tendon sheath. The finger feels better when it is bent (flexed). Moving the finger can cause extreme pain. Fever is common.
Doctors base the diagnosis of infection of the tendon sheath on an examination. They do x-rays to detect foreign bodies (such as a tooth fragment, needle, or other object) that may be hidden under the skin.
To identify the type of bacteria that is causing the infection, doctors remove a sample of pus from the abscess and try to grow (culture) the bacteria in a laboratory.