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Trigger Finger

 

What is trigger finger or trigger thumb?

Trigger finger and trigger thumb are some of the most common conditions I treat in my office. It is due to a swollen part of the tendon at the base of the digit. It can cause a painful popping and clicking in the finger or thumb as the patient flexes or extends the digit. It is very common for this to occur just when you wake up in the morning. If the condition is not treated, it will commonly worsen to the point that the patient cannot fully straighten the finger (or sometimes cannot flex, although that is less common). The painful popping and clicking is called "triggering" (this is where the name comes from) and the inability to fully straighten is called "locking".

 

 

The Palm of the Hand


This is a view of the palm side of the hand. The tendons, shown in white, pass into the finger inside a tendon sheath, shown as a slightly bluish-white. This sheath functions to keep the synovial fluid (the "tendon oil") around the tendon. The synovial fluid lubricates the tendon as it moves back and forth in the finger. The beginning of the sheath is called the A1 pulley. Note the digital (finger) artery and nerve. They are very close to the pulleys. The illustration below shows an enlarged view of the pulley system.

This illustration shows the tendon sheath, and shows how it has some thicker regions that are divided into named structures called pulleys. The A1 region is the one that gets involved in trigger finger. There is a similar division, but much simpler, in the thumb.

The purpose of the pulleys is to keep the tendons close to the bone (see the smaller illustration above, to the left). As the finger bends (flexes), the pulleys prevent the tendons from sagging away from the bone.

In trigger finger, there is some swelling of the tendon, due to a variety of factors, mostly processes of aging. The swollen part of the tendon "pops" under the A1 pulley, causing the finger to "pop" or not bend smoothly. Often the patient thinks it is the joint that is popping, but it is the tendon that moves that joint that is popping.

What causes trigger finger?

We do not know exactly what causes trigger finger, but we do know some things. The tendon is subjected to significant forces at the A1 pulley, which is where trigger finger occurs. Trigger fingers show changes in the substance of both the tendon and the pulley called "fibrocartilaginous metaplasia", which means that some of the cells change into cells that have the characteristics of cartilage cells such as those found in inter-vertebral disks. The cells show an increase in both the size of the cells and the number of cells. The smooth gliding layer of the tendon and the pulley change, with fraying and disintegration of the surface. We do not see these high forces or cellular changes in other areas of the flexor tendons, therefore we feel that these changes must be related to the disease called trigger finger. (Trigger Digits: Diagnosis and Treatment, by Miguel J. Saldana, MD; Journal of the AAOS, July/August, 2001, pages 246-252).

In addition, the molecules of the collagen (collagen makes up about 95% of the substance of a tendon) degrade and break up. The degradation products of the collagen, called "mucinous degeneration", accumulate within the tendon, enlarging the area. This in part creates the bump or swelling of the tendon. This seems to be a natural part of aging (like gray hair and wrinkles) and is not a sign of disease.

 

What are the symptoms of trigger finger?

The hallmarks of trigger finger is painful popping of the digit and pain in the palm at the A1 pulley level. The popping is usually worse in the morning when you first get up, but as the problem progresses, it can pop all the time. When it is really bad, the bump in the tendon cannot pass under the pulley and the finger is "locked", that is, it cannot straighten (or bend, if it is stuck out straight).

 

Who gets trigger finger?

Many people think trigger finger should come from a long history of hard work, but hard labor does not seem to be very related. It can come from an episode of overuse, but is usually not associated with any period of heavy use. It usually comes on gradually, and typically comes in our 40's, 50's, and 60's. It is about two to three times more common in women than in men, and the fourth finger is the most often involved. It is common for patients to get it in more than one finger. If they do, it is often either the same finger in both hands, or two adjacent fingers. Most patients will get it in only one or two fingers.

 

How is trigger finger diagnosed?

The diagnosis is made by listening to the patient and by examining the patient. Most patients will have a history of painful clicking and popping, without any history of trauma. There will be a painful nodule in the palm, exactly at the A1 pulley location.

 

How is trigger finger treated?

You start out with diagnosis. In the case of trigger finger, the making of the diagnosis is usually quite simple. The next step is very important: patient education.

The third step in the general treatment regimen for all hand problems is activity modification. This step does not really apply much to trigger finger. It is usually not due to overuse.

The fourth step in my general treatment regimen for all hand problems is anti-inflammatory medication. This usually does not help in the treatment of trigger fingers. It is not strictly an inflammatory condition, since the changes are not just the changes of inflammation, but of fibrocartilangenous metaplasis (see section above for explanation).

The fifth step in my general treatment regimen for all hand problems is splints. While they will work as long as you wear the splints, you will not be able to do anything with your hand. If the trigger digit was minimally symptomatic and you happened to do something that made your hand swell, a temporary splint may help. However, splints usually are not a part of the treatment of trigger finger.

The sixth step in the general treatment regimen for all hand problems is hand therapy. While we use a lot of hand therapy in our practice, there is not much that hand therapy can offer this condition.

The seventh step in my general treatment regimen for all hand problems is steroid injection, and this is a great way to treat trigger fingers. About 50% of all trigger fingers will be completely resolved with injections, although it may take more than one. It is not a good idea, in general, to give more than three injections in any one location in the body, as it can cause some collagen degeneration. You can have three in each involved finger, but not more than three in any one finger. If a finger has been locked, the injection will often resolve the locking, but it probably will not be completely effective in resolving the problem, and you are more likely to proceed to the next step.

The final step is surgery. About 50% of trigger fingers go on to surgery. The longer you waited to come see me, the greater the chance that you will need surgery. Of all the surgeries I do, this is the simplest. It is out-patient surgery (that is, you don't stay overnight in the hospital). You don't even have to eat the hospital food! (Although I rather like the Marin General Hospital food, and think that they do a good job.)

The risks of surgery are minimal, but not zero. Infection, failure to relieve the triggering, recurrence of triggering, or damage to local structures are the main complications, and should be at about the 1% level.

 

What Surgery Involves.

 

What Can I Expect After Surgery?

Predicting the future is difficult, but we can tell you what is typical for most cases and for most patients. All the sutures will be under the skin, like a Hollywood movie star's plastic surgery, so you will not see the sutures and there will not be any sutures to be removed. Nice, eh? You will have a small dressing on your palm, but not on your wrist or finger. You can use your hand gently, even the day of surgery, but it will be numb for 8 to 24 hours. The dressing must be kept dry (see post operative instructions ) for five days, so use a plastic bag to shower. On the third or fourth day, you can take the dressing off and place a band aid. Two days later, you can get rid of the band aid and get it wet in the shower. You can get it wet in dishwater or a hot tub at 7 days after surgery. Use you hand gently, but it is exceedingly rare for someone to be able to open their incision (has happened four times in 20 years, but only due to falling on the hand!) Gradually increase your activities. It is hard to predict exactly how quickly each patient will return to activities, as there are many variables, including the exact procedure performed, how active the patient normally is, how much discomfort each patient will tolerate before they limit their activities, etc. However, many people will drive the next day, type in a day or two, resume serious keyboard use in a week or two, play tennis in 1-3 weeks, return to paperwork jobs in 1-2 weeks, return to manual labor jobs at 3-4 weeks. We will discuss the particulars of your surgery and recovery with you in the office.