Trigger Finger

The flexor tendons that bend the fingers each pass through a series of pulleys — ring-like structures that keep the tendons close to the bone as the finger moves. The A1 pulley, located at the base of each finger just over the metacarpophalangeal (MCP) joint, is the first and most clinically important of these pulleys. In trigger finger, repetitive friction causes the A1 pulley to thicken and narrow. Simultaneously, the flexor tendon may develop a reactive swelling or nodule just proximal to the pulley.

The result: the tendon can no longer glide smoothly through the pulley. As the finger bends and then attempts to straighten, the tendon catches on the narrowed pulley, producing the characteristic triggering sensation. In advanced cases, the finger becomes locked in flexion and must be physically straightened with the other hand — or cannot be straightened at all.

Quinnell Grading System:

• 0 — Normal movement
• 1 — Uneven movement
• 2 — Active triggering — momentary catching
• 3 — Passive triggering — requires gentle passive correction
• 4 — Fixed — cannot be straightened even passively

Who Is Affected?

Trigger finger is more common in women than men, with peak incidence in the fifth and sixth decades. The ring finger and thumb are most frequently affected, followed by the middle and index fingers. Bilateral or multiple-finger involvement is common.

Risk factors include:

• Diabetes mellitus: One of the strongest risk factors. Diabetic patients are 5–10× more likely to develop trigger finger and have a significantly lower response rate to corticosteroid injection.
• Rheumatoid arthritis and other inflammatory arthropathies
• Hypothyroidism
• Amyloidosis
• Repetitive gripping and sustained hand use
• Dupuytren's contracture (palmar fibrosis affecting adjacent structures)

Treatment options

Frequently Asked Questions