Trigger Finger

WHAT IS TRIGGER FINGER?

Trigger finger, also called “Stenosing Tenosynovitis”, is a common hand condition. The first indication of the condition may be slight stiffness or even “clicking” when flexing the finger/thumb especially in the morning. This is often associated with some discomfort. If it progresses, one may need to use your other hand to bend or straighten the finger. When the finger does move, a snap or click may be felt, as it suddenly gets “unstuck”. This is the triggering that gives the condition its name. It can get to thestage where every time you flex the finger in locks into position and has to be forcibly straightened.

HOW DOES THE PROBLEM DEVELOP?

On the front of each finger is a series of pulleys forming the flexor tendon sheath that provides a smooth tunnel which allows the tendons to glide through and flex the finger.

Trigger finger/thumb occurs when the pulley at the base of the finger (A1 pulley) becomes thickened and constricting around the tendon, making it difiicult for the tendon to move freely through the pulley. Sometimes the tendon develops a nodule or swelling of its lining. Due to 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.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.

WHAT CAUSES TRIGGER FINGER?

In most cases there is no clear cause. It is common in middle aged women and in certain systemic conditions such as rheumatoid arthritis, gout, and diabetes. Local trauma to the palm/base of the finger may be a factor on occasion. Also, highly repetitive work involving gripping actions is associated with this condition. Triggering can also result in patients who have had a partial tendon injury.

HOW IS IT DIAGNOSED?

Trigger finger/thumb may start with discomfort felt at the base of the finger or thumb, where they join the palm. This area is often tender to local pressure. A nodule may sometimes be found in this area. When the finger begins to trigger or lock, the patient may think the problem is at the middle knuckle of the finger or the tip knuckle of the thumb, since the tendon that is sticking is the one that moves these joints.X-rays and other tests generally are not needed unless multiple fingers are triggering.

HOW IS IT TREATED?

Principles
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.
Conservative
The wearing of a splint or taking an oral anti-inflammatory medication very occasionally helps. Treatment may also include changing activities to reduce swelling.

Steroid Injection
This is especially helpful in recent onset triggering. An injection of steroid into the area around the tendon and pulley can be effective in relieving the trigger finger/thumb. This should not be performed more than twice as it can damage the tendon.

Surgical
If non-surgical forms of treatment do not relieve the symptoms, surgery may be recommended. This surgery is performed as a day only procedure, and occasionally under local anaesthetic only. This Involves making a small incision in the palm and incising the tight A1 pulley so that the tendon can glide more freely.

PROGNOSIS
After the procedure, finger exercises and general hand use is encouraged immediately and allowed as comfort permits. Stitches (usually no more than 3 or 4) are removed between 10–14 days post-operatively. Occasionally, hand therapy is required after surgery to regain better use. Recovery usually is complete within a few weeks.
RISKS
Surgery is usually very successful and the benefits are immediate. However, like all surgery some problems can arise.
Recurrence
It is very uncommon for the triggering to recur. This is most likely when the tenosynovitis is generalised (affects many parts of the body). It is much more common that the triggering will arise in another finger in these conditions.

Digital nerve injury
Small digital nerves run very close to the tendons and they should be identified and protected during surgery. Infrequently they can be injured during surgery (< 1 in 1000). Complex regional pain syndrome (CRPS)
This is an uncommon condition that can occur after hand trauma or surgery (<1 in 2000). This causes hand pain, sweating, skin changes, stiffness and swelling. Early recognition of this problem and aggressive treatment by a physiotherapist and pain management specialist is required to minimize the development of chronic hand problems.