WHAT IS TRIGGER FINGER?
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). The catching or triggering action is distinctive. When the tendon catches, it produces inflammation and more swelling. This causes a vicious cycle of triggering, inflammation, and swelling. Sometimes the finger becomes stuck or locked, and is hard to straighten or bend.
Figure 1(a): Anatomy of the finger flexor sheath. Normal flexor tendon anatomy showing the relationship between tendon, tenosynovium and pulley.
Figure 1(b) : A thicken flexor pulley causing triggering. In trigger finger, the pulley is thickened and tight, and the tendon can also be enlarged, causing ‘catching’ during movements.
SYMPTOMS AND CAUSES OF TRIGGER FINGER
Symptoms often start without any preceding injury.
Trigger finger is a common problem that causes locking and clicking of the finger. There is tenderness in the palm and movement of the finger, especially straightening, can be quite painful. Some people have to use their other hand to straighten a trigger finger when it locks.
This is often associated with swelling or a small lump in the palm, and a click or popping sensation can be felt as the nodule passes through the sheath when extending the finger.
Stiffness and catching tend to be worse after inactivity, such as in the mornings when you wake up, but will often loosen up with movement. In severe cases the finger may become stuck in a bent position so that it can't be straightened even with the help of other fingers. One or more fingers can be involved. Dr. Lee will diagnose the problem by talking with you and examining your hand.
Trigger fingers are more common in women than men. They occur most frequently in people who are between the ages of 40 to 60 years. Some trigger fingers are associated with medical conditions such as rheumatoid arthritis, gout, and diabetes. Overuse injury (e.g. heavy use of a computer keyboard or computer mouse); or local direct trauma to the palm/base of the finger may be a factor on occasion, but in most cases there is not a clear cause and can result from normal daily activity as we age.
These are the symptom that could occur:
Stiffness in the finger, especially in the morning
When trying to move or bend the fingers, there’s a pop or click sensation
The spot at the base of your finger where the palm meets the finger is tender
There’s a bump or nodule at the same spot where your palm and the base of your finger meet
In the bent position, the finger(s) is locked for an extended periods of time and you are not able to straighten or move the finger back to the strait position
TREATMENT AND SURGERY FOR TRIGGER FINGER
The goal of treatment in trigger finger/thumb is to eliminate the catching or locking and allow full movement of the finger or thumb without discomfort. Swelling around the flexor tendon and tendon sheath must be reduced to allow smooth gliding of the tendon.
Initial treatment for mild or infrequent symptoms of trigger finger include rest, splints, avoiding or modifying those activities that caused the inflammation, and the use of a non-steroidal anti-inflammatory (NSAID) medications.
For mild to moderate cases, a Cortisone Injections into the tendon sheath is an option to treat trigger finger. Injections are less likely to bring about permanent relief when the triggering has been present for a long time, or if you have associated medical problems like diabetes.
In more severe cases, surgery may be required to relieve the symptoms. Through a small incision in the palm of the hand at the base of the affected finger or thumb, the entrance to the flexor tunnel is opened allowing the tendon to glide back and forth freely. This procedure is performed under local anaesthesia and usually takes less than 15 minutes. This is done as same day surgery with a small soft dressing applied to the hand. Relief of symptoms is immediate and the finger can be moved immediately.
New minimally invasive surgical techniques are available for the treatment of trigger finger.
Delaying treatment can result in progressive joint stiffness and contractures, which may then require additional therapy. Early treatment is advised for the best results and faster recovery.
