Trigger Finger Treatment London | Private Ultrasound Diagnosis & Injections

Trigger Finger Explained

Trigger Finger Anatomy

The flexor tendons of the wrist, hand, and fingers transmit force from the forearm muscles to allow us to manipulate, grip, and move the fingers and thumb independently.

To stabilise each tendon and prevent the tendons from bowstringing across the palm and fingers, they are enclosed in a tunnel called the flexor tendon sheath. Additionally, this sheath and the tendon are further stabilised and reinforced in the palm of the hand and down the length of the fingers by a series of pulleys, which bind the tendon sheath to the underlying structures.

Trigger finger or trigger thumb describes a condition in which these pulleys become painful and inflamed. This most commonly occurs at the point where the palm of the hand meets the finger, in the region of the A1 pulley.

It is uncommon for the flexor tendon itself to develop degenerative changes or tears — such changes typically occur only following trauma.

Trigger Finger Symptoms

The name “trigger finger” comes from the fact that when inflamed, sufferers may notice a click or triggering sensation as the thumb or finger moves from flexion to extension.

Occasionally, the finger or thumb may become completely locked in a flexed position, requiring the individual to manually release it.

What Causes Trigger Finger?

The causes of developing a trigger finger include a genetic propensity as well as this condition being common in diabetic individuals who have a high likelihood for low grade inflammation in these tissues. 

In some individuals, tasks involving significant gripping and loading the flexor tendons or trauma to the palm of the hand or finger may trigger an onset of inflammation to the A1 pulley.

Trigger Finger Diagnosis

Due to the anatomy of this region, an ultrasound scan is the imaging modality of choice to confirm suspected trigger thumb or trigger finger.

Ultrasound can:

• Exclude degenerative changes or inflammation of the underlying metacarpophalangeal joint

• Clearly visualise the flexor tendon body to exclude tears

• Clearly visualise the affected A1 pulley in longitudinal view with the probe aligned along the long axis of the finger

• Visualise the pulley in transverse view, with the probe placed across the base of the finger

In some cases, an inflamed A1 pulley may cause adjacent issues. For example, flexor tendon tenosynovitis may coexist, where inflammation and fluid develop within the tendon sheath, in addition to inflammation of the pulley itself.

Another possible complication is the development of a ganglion cyst — a fluid-filled cyst that may arise from the A1 pulley and extend into the subcutaneous fat layer.

Trigger Finger Ultrasound Guided Injections

How is a Trigger Finger injection administered?

An ultrasound-guided injection can be effectively used to reduce inflammation and swelling of the A1 pulley.

There are two common techniques to deliver this injection:

1️⃣ The probe is placed in longitudinal axis along the finger, with the A1 pulley visualised at the near edge of the probe. The clinician can then visualise the needle passing from the near edge of the probe into the A1 pulley, with the injectate delivered at the tendon-pulley interface.

2️⃣ In patients with limited finger mobility, it may be difficult to position the probe longitudinally. In this case, the probe is placed in a transverse orientation at the base of the finger. A centreline is used to align the A1 pulley and flexor tendon at the centre of the image, and the needle is advanced along this line, with depth judged to visualise the needle reaching the A1 pulley-tendon interface.

If a ganglion cyst is present, the procedure can be adapted to manage this alongside the trigger finger injection. Under ultrasound guidance, the ganglion cyst is first aspirated using a needle with initial local anaesthetic to numb the area. Once the fluid is aspirated, the walls of the cyst are disrupted mechanically using the needle to help prevent recurrence. Following this, a second needle is introduced into the area, and a small amount of corticosteroid is injected into the cyst cavity and surrounding tissues to reduce inflammation and promote resolution.

What to Do After Your Trigger Finger Injection

Needle Path & Post-Injection Pain
During a trigger finger injection there may be pain as the needle path has to go through the palm of the hand at the painful site. This is reduced by performing a trigger finger injection accurately and quickly under experienced hands and with ultrasound guidance. This pain will quickly settle following an ultrasound guided injection for trigger finger and it is rare for there to be any post injection flare of pain. If there is any post injection flare then over-the-counter painkillers (as directed on the patient information leaflet) can be taken.

Wound Care & Infection Risk
Avoid exposing the needle site to public or dirty water (e.g., swimming pools, hot tubs, lakes) for 2–3 days after any ultrasound-guided injection, due to the small infection risk.

Activity Guidance
After a trigger finger injection, it is advisable to avoid any significant increase in activity for 10 days and during this time to wear a splint over night which will allow the anti-inflammatory properties of the steroid to work optimally.
Following this period, you should engage in a progressive program of physical therapy exercises.

Follow-Up
Following an trigger finger injection, please contact me immediately if you experience any difficulties.

Other Treatments for Trigger Finger

Trigger Finger Splint

Trigger Finger Physical Therapy Exercises

Trigger Finger | Evidence base

Trigger finger is a common condition caused by thickening of the A1 pulley and associated flexor tendon tenosynovitis, leading to painful clicking, locking, or fixed flexion of the affected digit. The condition may resolve spontaneously in some cases, but symptoms often persist or progress without treatment. The evidence strongly supports corticosteroid injection into the flexor tendon sheath as first-line intervention for most patients, with high rates of symptom resolution, particularly in early or moderate disease. Ultrasound guidance improves injection accuracy, allowing precise delivery into the tendon sheath while avoiding intratendinous injection, and facilitates identification of pulley thickening, nodules, and concurrent tenosynovitis. Studies comparing US-guided to landmark-guided injection suggest higher success rates, faster symptom resolution, and reduced post-injection pain, especially in patients with diabetes, multiple affected digits, or recurrent symptoms. Most patients respond to a single injection, though a second injection may be considered if symptoms recur; repeated injections should be limited due to diminishing returns and potential tendon weakening. Surgical A1 pulley release is reserved for patients with persistent triggering after failed injection therapy or with fixed locking. Overall, ultrasound-guided corticosteroid injection is a highly effective, low-risk treatment for trigger finger and remains the cornerstone of non-operative management.

Questions about your finger pain?