Trigger finger

Definition/diagnostic criteria Trigger finger, also known as stenosing tenosynovitis, is a common hand condition characterised by the locking or catching of one or more fingers, typically the thumb or one of the other digits. It occurs due to the inflammation and narrowing of the tendon sheath, which restricts the smooth gliding of the flexor tendon. The primary diagnostic criteria for trigger finger include pain, tenderness, clicking or stiffness in the affected digit.

Epidemiology Trigger finger is a relatively common hand condition in the UK. It is more prevalent among women and individuals aged 40 to 60 years. The exact prevalence rate varies, but it has been reported to affect approximately 2-3% of the general population. Risk factors for developing trigger finger include diabetes mellitus, rheumatoid arthritis and repetitive hand use.

Diagnosis
Clinical features: The clinical presentation of trigger finger is often distinctive and can include:

• Pain and tenderness: Patients frequently complain of pain and tenderness at the base of the affected finger, which may worsen with movement.
• Catching or locking sensation: The hallmark symptom is the sensation of the finger catching or locking in a flexed position, followed by a sudden release with a snap when trying to extend it.
• Swelling and palpable nodule: Swelling may be observed over the affected area, along with the presence of a palpable nodule at the flexor tendon’s base.
• Stiffness: Especially in trigger thumb where movement at the end joint is reduced.

Investigations: Clinical assessment is usually sufficient for diagnosing trigger finger. Ultrasound can confirm the presence of tendon thickening and the narrowing of the tendon sheath if there is diagnostic uncertainty. Xray can be considered if there is suspicion of underlying joint arthritis or bony abnormalities.

Treatment The management of trigger finger typically follows a stepped approach, with initial non-surgical measures recommended for mild to moderate cases:

• Analgesia: Over-the-counter pain medications, such as paracetamol and ibuprofen.
• Activity modification: Encourage patients to reduce activities that exacerbate symptoms, such as repetitive gripping or grasping.
• Splinting: Wearing a splint or brace to immobilise the affected finger can provide relief, especially at night.
• Corticosteroid injections: A local corticosteroid injection into the tendon sheath can reduce inflammation and relieve symptoms.
• Surgical release: Surgical release of the affected tendon sheath may be necessary if non-surgical treatments fail.

Prognosis With appropriate treatment, most patients experience a significant reduction in symptoms and an improvement in finger function. However, the recurrence rate after treatment can be relatively high, especially in individuals with underlying conditions like diabetes.