What is it?
Stenosing tenosynovitis, commonly known as “trigger finger” or “trigger thumb”, involves the pulleys and tendons in the hand that bend the fingers. The tendons work like long ropes connecting the muscles of the forearm with the bones of the fingers and thumb. In the finger, the pulleys are a series of rings that form a tunnel through which the tendons must glide, much like the guides on a fishing rod through which the line (or tendon) must pass. These pulleys hold the tendons close against the bone. The tendons and the tunnel have a slick lining that allows easy gliding of the tendon through the pulleys (see Figure 1). Trigger finger/thumb occurs when the pulley at the base of the finger becomes too thick and constricting around the tendon, making it hard for the tendon to move freely through the pulley. Sometimes the tendon develops a nodule (knot) or swelling of its lining. Because of the increased resistance to the gliding of the tendon through the pulley, one may feel pain, popping, or a catching feeling in the finger or thumb (see Figure 2). When the tendon catches, it produces irritation and more swelling. This causes a vicious cycle of triggering, irritation, and swelling. Sometimes the finger becomes stuck or locked, and is hard to straighten or bend. Figure 1: Normal anatomy flexor sheath showing pulley, tendon, and tenosynovium.
Tendon Pulley Tenosynovium
Figure 2: Abnormal anatomy showing tendon catching thick, tight pulley. Sometimes the tendon will be locally enlarged and thicker.
What causes it?
Causes for this condition are not always clear. Some trigger fingers are associated with medical conditions such as rheumatoid arthritis, gout, and diabetes. Local trauma to the palm/base of the finger may be a factor on occasion, but in most cases there is not a clear cause.
Signs and symptoms
Trigger finger/thumb may start with discomfort felt at the base of the finger or thumb, where they join the palm. This area...
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