Trigger finger

Alternative Name : Stenosing tenosynovitis, trigger thumb, or trigger digit,

Definition:
Trigger finger is a common disorder of later adulthood characterized by catching, snapping or locking of the involved finger flexor tendon, associated with dysfunction and pain. A disparity in size between the flexor tendon and the surrounding retinacular pulley system, most commonly at the level of the first annular (A1) pulley, results in difficulty flexing or extending the finger and the “triggering” phenomenon. The label of trigger finger is used because when the finger unlocks, it pops back suddenly, as if releasing a trigger on a gun.
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One of your fingers or your thumb gets stuck in a bent position and then straightens with a snap — like a trigger being pulled and released. If trigger finger is severe, the finger may become locked in a bent position.

Often painful, trigger finger is caused by a narrowing of the sheath that surrounds the tendon in the affected finger. People whose work or hobbies require repetitive gripping actions are more susceptible. Trigger finger is also more common in women and in anyone with diabetes.

Symptoms:
Signs and symptoms of trigger finger may get progressed from mild to severe and include:

*Finger stiffness, particularly in the morning

*A popping or clicking sensation as you move your finger

*Tenderness or a bump (nodule) at the base of the affected finger

*Finger catching or locking in a bent position, which suddenly pops straight

*Finger locked in a bent position, which you are unable to straighten

Trigger finger more commonly occurs in your dominant hand, and most often affects your thumb or your middle or ring finger. More than one finger may be affected at a time, and both hands might be involved. Triggering is usually more pronounced in the morning, while firmly grasping an object or when straightening your finger.

Trigger finger is not the same as Dupuytren’s contracture — a condition that causes thickening and shortening of the connective tissue in the palm of the hand — though it may occur in conjunction with this disorder.

Causes:
The cause of trigger finger is a narrowing of the sheath that surrounds the tendon in the affected finger. Tendons are fibrous cords that attach muscle to bone. Each tendon is surrounded by a protective sheath — which, in turn, is lined with a substance called tenosynovium. The tenosynovium releases lubricating fluid that allows the tendon to glide smoothly within its protective sheath as you bend and straighten your finger — like a cord through a lubricated pipe.

But if the tenosynovium becomes inflamed frequently or for long periods, the space within the tendon sheath can become narrow and constricting. The tendon can’t glide through the sheath easily, at times catching the finger in a bent position before popping straight. With each catch, the tendon itself becomes more irritated and inflamed, worsening the problem. With prolonged inflammation, scarring and thickening (fibrosis) can occur and bumps (nodules) can form.

More than one potential causes have been described but the etiology remains idiopathic. It has also been called stenosing tenosynovitis (specifically digital tenovaginitis stenosans), but this may be a misnomer, as inflammation is not a predominant feature.

It has been speculated that repetitive forceful use of a digit leads to narrowing of the fibrous digital sheath in which it runs, but there is little scientific data to support this theory. The relationship of trigger finger to work activities is debatable and scientific evidence for and against hand use as a cause exist.

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Risk Factors:
Risk Factors  developing trigger finger include:

Repeated gripping. If one routinely grips an item — such as a power tool or musical instrument — for extended periods of time, one may be more prone to developing a trigger finger.

Certain health problems. One is also at greater risk if he or she has certain medical conditions, including rheumatoid arthritis, diabetes, hypothyroidism, amyloidosis and certain infections, such as tuberculosis.Your sex. Trigger finger is more common in women.

Diagnosis:
Diagnosis is made almost exclusively by history and physical examination alone. More than one finger may be affected at a time, though it usually affects the thumb, middle, or ring finger. The triggering is usually more pronounced in the morning, or while gripping an object firmly.

Treatment:
Injection of the tendon sheath with a corticosteroid is effective over weeks to months in more than half of patients.

 

When corticosteroid injection fails, the problem is predictably resolved by a relatively simple surgical procedure (usually outpatient, under local anesthesia). The surgeon will cut the sheath that is restricting the tendon.

One recent study in the Journal of Hand Surgery suggests that the most cost-effective treatment is two trials of corticosteroid injection, followed by open release of the first annular pulley.  Choosing surgery immediately is the most expensive option and is often not necessary for resolution of symptoms.  More recently, a randomized controlled trial comparing corticosteroid injection with needle release and open release of the A1 pulley reported that only 57% of patients responded to corticosteroid injection (defined as being free of triggering symptoms for greater than 6 months). This is compared to a percutaneous needle release (100% success rate) and open release (100% success rate).  This is somewhat consistent with the most recent Cochrane Systematic Review of corticosteroid injection for trigger finger which found only 2 pseudo-randomized controlled trials for a total pooled success rate of only 37%.  However, this systematic review has not been updated since 2009.

There is a theoretical greater risk of nerve damage associated with the percutaneous needle release as the technique is performed without seeing the A1 pulley.

Investigative treatment options with limited scientific support include: non-steroidal anti-inflammatory drugs; occupational or physical therapy; steroid iontophoresis treatment; splinting; therapeutic ultrasound, phonophoresis (ultrasound with an anti-inflammatory dexamethasone cream); and Acupuncture.

Prognosis:
The natural history of disease for trigger finger remains uncertain.

There is some evidence that idiopathic trigger finger behaves differently in people with diabetes.

Recurrent triggering is unusual after successful injection and rare after successful surgery.

While difficulty extending the proximal interphalangeal joint may persist for months, it benefits from exercises to stretch the finger straighter.

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose.

Resources:
http://en.wikipedia.org/wiki/Trigger_finger
http://www.mayoclinic.com/health/trigger-finger/DS00155
http://assets.sbnation.com/imported_assets/71765/trigger_finger_2.jpg
http://www.trigger-finger.com/
http://www.drmomeni.com/hand/trigger.html

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