Ultrasound-Guided Thumb Base (CMC) Joint Steroid Injection

Ultrasound guided Trigger finger steroid injection

What is Trigger Finger?

Trigger finger is a mechanical condition characterised by finger locking and clicking due to the abrupt movement of the finger flexor tendons as they pass through special fibrous structures called pullies. The clicking can be audible and painful. The symptoms of a trigger finger are usually mild to start with but can worsen over time, causing the finger to become stuck in a bent position, making it very difficult to straighten. The likelihood of developing a trigger finger increases with age.
Unfortunately, as the tendon and the pulley become inflamed and thickened, further attempted movements of the fingers will result in further irritation, swelling and discomfort. Therefore, the condition can significantly interfere with hand movements and functions.

What are the risk factors for developing a trigger finger?

Age- the incidence increases with age.

Diabetes- The condition is more common in diabetics.

Occupation- manual jobs that involve repeated and forceful gripping can predispose to triggering.

Sports activities. Particularly climbing, as the sport can put extra stress on the fingers.

How do I know if I have a trigger finger?

The triggering tends to involve the thumb, middle and ring fingers more than others. Patients may wake up with a finger bent towards the palm, which is usually painful to straighten and requires significant force. The finger movement will be generally uncomfortable, with catching sensation and clicking. Finger swelling is a sign of tendon irritation and inflammation.

What other conditions can mimic a trigger finger?

The diagnosis is usually easily established by clinical assessment. Conditions that can be mistaken for a trigger finger include:

Carpal Tunnel Syndrome
Thumb osteoarthritis
Dupuytren's Contracture.

Dupuytren's Contracture vs trigger finger

In Dupuytren's contracture, the palmar fascia is thickened (a thin layer of tissue underneath the palm surface). Palmar fascia thickening will pull the underlying finger tendons causing them to bend (flex); therefore, it may be mistaken for a trigger finger. The bending is usually more noticeable in the ring and little fingers. Straightening the fingers in a trigger finger is usually possible with force, while in Dupuytren's contracture, the thickened fascia will prevent finger straightening, even with assistance from the other hand!

Trigger finger vs carpal tunnel syndrome?

Trigger finger pain typically involves one finger; by contrast, carpal tunnel typically causes discomfort, pins-and-needles sensations, and weakness across multiple fingers.

How to diagnose a trigger finger?

When the condition is suspected clinically after assessment by a hand specialist, an ultrasound can be very useful to confirm the diagnosis. It will accurately show any thickening or inflammation within the tendon/tendon sheath and the pulley system. Ultrasound also allows direct visualisation of the tendon as it moves underneath the pulley. This is called dynamic ultrasound assessment and often demonstrates tendon catching.

What are the treatments options for trigger finger?

The treatment starts with conservative measures, including activity modification and physiotherapy (mainly stretching exercises). However, the condition can persist despite the above measures. An ultrasound-guided steroid injection may be recommended in resistant cases and severe disease when the fingers become locked in a bent position.

Ultrasound-guided steroid injection to treat Trigger Finger

An ultrasound-guided steroid injection can be very helpful for this condition. A small dose of corticosteroid is injected under ultrasound guidance accurately into the thickened tendon sheath just underneath the pulley. Usually, patients notice an improvement in their symptoms with a single steroid injection. Sometimes, a repeat injection is considered after 2-3 months if the response from the first injection is incomplete.

What are the possible side effects of trigger finger steroid injection?

The potential adverse effects from trigger finger steroid injections are minimal, as only a safe, low dose of cortisone is used. These include steroid flare, infection, focal skin thinning, focal skin colour changes, or tendon weakening. Steroid flare refers to temporary pain at the injection site due to local irritation. Focal skin colour changes may consist of a small area of skin depigmentation (lightening of the skin colour) or fat atrophy (focal thinning to the fat layer underneath the skin that may result in dimpling). Overall, serious adverse reactions are uncommon. For more information, please see our FAQs.

Does trigger finger steroid injections need to be done under ultrasound guidance?

In addition to the role of ultrasound in confirming the diagnosis and assessing the severity of the condition, it is essential when performing a trigger finger injection. Ultrasound allows for accurate needle placement within the inflamed tendon sheath, thus improving effectiveness.

Can Cortisone injections be done for a trigger thumb?

Trigger thumb is also common. Similar to the other fingers, ultrasound-guided cortisone injections for a trigger thumb can be done to reduce inflammation and treat the condition.

What are the other treatment options to treat a trigger finger?

Other treatment options include surgical pulley release and percutaneous trigger finger release. The latter refers to a special procedure where a small specific blade cuts the pulleys without skin cutting or suturing.