Causes And Treatment Of Trigger Finger, A Common Hand Problem

With the internet at your fingertips, most adults use this resource to get information about their perceived  disorder or injury. Often the wealth of information can be overwhelming and at times misleading.  It’s interesting however to note that not all patients comprehend what’s going on within their bodies to cause a particular disease or set of symptoms. This article will provide you with a better understanding of the anatomy and pathophysiology of the condition known as trigger finger, as well as a brief discussion of the causes and possible treatment options.

A tendon is like a piece of rope that connects muscle to bone. Each finger has three tendons that work in harmony and permit precise movement of the finger to facilitate fine activities like writing, picking up a coin, turning a key and also more composite movements like gripping a hammer or lifting your shopping.

If left unchecked, as you bend your  finger the two tendons on the palm side of the finger would naturally bow string away from finger. To prevent this and improve the efficiency of the tendon, there are little pulleys along the finger. 

However at times this awesome mechanism runs into problems and the tendon  that bends your finger has difficulty fitting through the tight sheath, or pulley, that holds it close to the bone near the base of your finger in the palm. When this happens the finger may lock or get stuck bent and you then have to physically straighten it and when this happens it is referred to as a “trigger finger”. This resembles the pulling and release of the trigger of a gun and hence the name. It occurs when inflammation narrows the space within the sheath that surrounds the tendon in the affected finger.

When you bend your finger, you may feel a little bump in your finger at the level of the base of the finger, usually at the level of the distal crease in the palm. As you bend and straighten the   finger and the tendon glides you may feel the little bump (nodule)  glide up and down. This usually relates to a reactive nodule on the tendon which Hueston and Wilson proposed was due to chronic repetitive friction between the flexor tendon and the enclosing sheath They compared this with the fraying that occurs at the end of a piece of thread after it has been passed numerous times through the eye of a needle. Pathology studies have shown that the inner lining of the pulley also gets significantly thickened and narrows the space available for the tendon to glide and causes it to catch and lock. Triggering can also occur in the thumb.

Morning symptoms appear to be the most severe. Nobody knows why trigger finger develops in some people but not others, or in one finger but not the others. Conditions like diabetes and thyroid disease, like rheumatoid arthritis, have an increased association  with developing one or more trigger fingers. Trigger fingers can be quite painful, and most patients seek therapy because of the pain and loss of use of the finger. In the very severe cases the affected finger may stay locked and bent and can be very painful to straighten out.

Splinting and hand therapy is the first step in the ladder of treatment options available. A good therapist can make a custom made splint that stops you bending the digit completely but permits glide of the tendon. This is effective in a large number of cases but requires up to 6 weeks of treatment. Combination with topical or oral anti-inflammatory medications( providing no contraindications like allergy, asthma or stomach ulcers etc) can help manage the pain and inflammation.

If splinting fails or the symptoms have been present for a while, Long-acting corticosteroid injections are the next step up on the ladder in initial management of the symptomatic trigger digit. Injection of the involved flexor tendon sheath provides long-term relief of symptoms in 80% of affected digits with up to 2-3 injections. The injections can be done in clinic or by a radiologist under ultrasound guidance. A recent article in the bone and joint journal has suggested that the small dose of a single injection into the digit is acceptable and does not increase your susceptibility to COVID-19. It is however advisable to have a minimum 2 week interval between your vaccination and a steroid injection. The injection can be painful and it is not advisable to drive immediately after the injection. You may need some initial additional painkillers.

If non-operative treatment fails, surgery is the final step in the ladder. This can be performed in a number of ways but the main goal is to release the so-called A1 pulley, which is where the tendon becomes caught. The tight pulley is separated after surgery, allowing your tendon to move without catching. 

The surgery can be  performed using a local anaesthetic and a needle to divide the pulley through the skin (percutaneous trigger finger release) under ultrasound guidance by a radiologist in an outpatient room. This method has slightly better short term results in experienced hands  but the long term outcomes are so far better in the open group.

Open trigger finger release is performed in a procedure room or operating room using a local anaesthetic (with or without a tourniquet on the arm) and making an incision divide the pulley under direct visualisation. The procedure takes only a few minutes and stitches are usually applied to close the wounds. The wounds take about 2 weeks to heal up but may be sore for up to 6 weeks. 

It’s noteworthy to observe that different treatment strategies have different success rates. About 80% of the time, a series of up to two injections is deemed to be successful. If conservative treatment fails or you decide to proceed to surgery, open surgery has a success rate of about 95 percent, while percutaneous surgery has a success rate of roughly 80 percent. 

Infection, nerve damage (to the digital nerves that run next to the flexor tendons and supply sensation to your fingers), tendon damage, failure to relieve symptoms (due to incorrect diagnosis or unusual cause of the triggering), loss of motion after surgery, continued tenderness, stiffness and swelling and complex regional pain syndrome are all risks associated with trigger finger surgery, as are many other hand surgeries. The chances of developing any of these issues are low, (1-5%).

The important points to remember  after surgery, regardless of how it is done, are to keep the bandage clean and dry, and to begin bending your fingers as per the hand therapists advise. While awake, you’ll need to work on finger motion every hour. Elevate your hand as much as possible over the first 48 hours. You can immediately begin using your hand for light activities (up to 1-2 lbs of lifting). The sutures (if there are any) will be removed 10-12 days following the surgery. It is common for the area at the base of the finger to be uncomfortable for up to two months, although most people return to normal activities within two to three weeks.

In summary, splinting and hand therapy are a good first line treatment for trigger finger. Long acting corticosteroid injections are the mainstay in the initial management of this pathology. Surgery is curative and has very good long term outcomes but is best reserved for when non-operative management fails. It is important to remember that we can’t speed up biology and that we have to respect the soft tissues and give them time to heal. Movement is good, heavy lifting however is not advised till the healing is complete.