Trigger Finger Injuries

What Are Trigger Finger Injuries?

Trigger finger injuries are a disorder of the hand that causes fingers to become stuck in a bent position that appears similar to when someone is pulling the trigger of a gun. Most trigger finger injuries involve swelling in a tendon at the end of the finger, which impairs the ability of the digit to straighten out after bending. These tendons, and not muscles, are responsible for movement along the length of the fingers. Damage or dysfunction in these structures may considerably restrict the motor dexterity or function of the hand. Despite its name, trigger finger injury is most commonly seen in the third finger. It is least common in the pinky finger. In some cases, more than one finger is affected.

Trigger fingers may be associated with other symptoms, such as clicking or locking of the affected finger. Initially, the condition may be painless, but may become increasingly painful over time. Some patients may experience stiffness and a progressive loss of free movement in the finger without locking or clicking. This disorder is associated with some risk factors, or conditions and demographics that have been observed to be related to an increased incidence of trigger finger.

These include:

• Amyloidosis
• Carpal tunnel syndrome
• Female gender (trigger finger is approximately six times more common in women than men) and advanced age (i.e. women of roughly forty to sixty years)
• Hypothyroidism
• Long-term diabetes (but not hyperglycemia)
• Kidney disease
• Obesity
• Rheumatoid arthritis

Causes of Trigger Finger Injuries

The development of a trigger finger injury is associated with the inflammation of a tunnel-like sheath of tendon located near the juncture of the hand and finger. This wraps around the main tendon (also known as the flexor tendon) that runs through the finger. Inflammation that may be attributable to the conditions listed above can result in swelling around the tendon, which prevents it from “sliding” back to allow finger extension after bending.

Trigger finger may also be associated with hypertrophy (or abnormal growth) of this sheath. Some cases may also be caused by growths or swelling in other tissues in the vicinity of the tendon, including nervous tissue. These may be visible or palpable under the skin. Trigger finger injuries mainly occur in the first sheath tendon leading away from the palm. It is not clear if there is a direct causative factor of trigger finger injury. Some scientists propose the theory that it is associated with repetitive stress due to repeated hand movements such as gripping or flexing. Some research has found a link between trigger finger injury and people in occupations involving activities such as sewing and typing.

Treatments for Trigger Finger Injuries

Treatment for this condition may begin with conventional therapies such as splinting. This is the retention of the affected finger(s) in a neutral position, which may alleviate pain and inflammation by removing the variable of friction between the flexor tendon and the swollen sheath tendon. The finger may be fixed by a device like a brace or cast.

Another conventional option is drug therapy that reduces inflammation and also treats pain, if present. These may include common painkillers such as aspirin and ibuprofen, which inhibit the formation of the body’s own inflammatory molecules. Other drug-based options for trigger finger injury include corticosteroid injections. This involves the administration of corticosteroids that also reduce inflammation, into or near the affected sheath tendon. Local anesthetics such as lidocaine may also be included in the injected formulation to relieve pain.

Corticosteroid injections may effectively improve symptoms, with a success rate of up to 80%. These results may last from a few weeks to a number of months, depending on the response of the individual patient. Corticosteroid injections are associated with side effects such as changes in the skin color of the injected area, infection, and temporary increases in the blood glucose levels of diabetic patients.

If the previously mentioned options fail, a patient may consider surgical intervention for more permanent relief. The main procedure indicated for trigger finger injuries is known as a “decompression” of the swollen sheath, or a pulley release. This procedure involves making incisions into the palm of the hand over the tendon, until the affected sheath is reached. The sheath is then sliced in two, from the end nearest the palm to the other nearest the finger. These procedures are typically performed under local anesthetic, with the patient lying on their back with the hand and arm extended palm upward. The local anesthetic inhibits pain, and allows the hyperextension of the affected finger, so that the sheath is easily accessible. This is associated with effective elimination of flexor tendon compression, and thus with full recovery from trigger finger injury.

Conclusion

Trigger finger injury is the result of inflammation of the A1 pulley (or sheath) tendon of the finger. This constricts the flexor tendon that runs through the finger and impairs extension of the digit when it is bent. Treatments for this condition include options such as splinting, NSAIDs, or corticosteroid injections. If these fail, surgical decompression of the pulley tendon may effectively treat trigger finger injury. A discussion with your specialist or physician will be of help if you think any of these treatments are right for you.

References

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