What is Trigger Finger?
Trigger finger is a common disorder of the hand
which causes a painful snapping or locking of the
fingers or thumb. The medical name for this
condition is stenosing tenosynovitis. Stenosing
refers to the narrowing of an opening or passageway
in the body. Tenosynovitis refers to inflammation of
the outer covering of the tendons that bend and
extend the fingers and thumb. The tendons are tough,
fibrous cords that connect the muscles of the
forearm to the bones of the fingers and thumb. This
muscle and tendon system enables one to bend the
fingers inward when making a fist, and extend them
The tendons glide through a protective covering
called the tendon sheath. The sheath is like a
tunnel, and is lined with a thin membrane called
synovium. The synovial lining helps reduce friction
as the tendons glide through the tendon sheath.
Areas of dense fibrous tissue called annular bands
or pulleys are also part of the tendon sheath. These
structures are attached to the bones of the fingers
and thumb, and hold the tendons close to the bones
over which they pass. Your Hand Center
physician will review this anatomy with you during
your office visit.
Trigger finger is often caused by inflammation of
the synovial sheath surrounding the tendons. It may
also result from enlargement of the tendon itself,
or narrowing of the first annular band (A1 pulley).
When inflamed, the normally thin covering of the
sheath may be thickened to several times its normal
size. This reduces the amount of space through which
the tendons are able to pass. The tendon is no
longer able to glide freely through the sheath, and
the tendon itself may swell up in a balloon-like
mass at the point where it tries to pass through the
Upon forceful bending of the finger or thumb, the
enlarged portion of the tendon is dragged through
the constricted opening. This motion is often
accompanied by a painful snap, and the finger or
thumb may be locked in a bent position.
Straightening the finger or thumb may require using
the non-affected hand to actually pull the finger
back into an extended position, causing another
painful snap as the swollen portion of the tendon
passes back through the sheath.
A trigger finger
(thumb) is a condition where the movement of the
affected digit is arrested for a moment while flexed
or extended and then continues with a jerk upon
continued effort. This is a result of thickening and
constriction of the mouth of the fibrous tendon
sheath through which the affected tendon travels.
This interferes with the normal free gliding of the
flexor tendon contained within the thickened sheath.
Trigger finger, also called as stenosing
tenosynovitis. Treatment varies depending on the severity of the
condition, and ranges from rest to medications to
What are the Causes?
The exact cause of trigger finger or thumb is not always
readily apparent. In many cases, however, this condition may be the
result of repeated strain of this area due to work or hobby activities.
Tasks that require repetitive grasping or the prolonged use of tools
(scissors, screwdrivers, etc.) which press firmly on the tendon sheath
at the base of the finger or thumb may irritate the tendons and result
in thickening of the tendons themselves or the tendon sheath. Symptoms
of trigger finger may also be associated with conditions such as
rheumatoid arthritis, gout, or metabolic disorders such as diabetes that
produce changes in connective tissues and synovium.
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