Inflammation of the fluid-filled sheath that surrounds a tendon (tenosynovitis) in the hand can lead to tendon entrapment and “catching” or “popping” as the digit or thumb flexes and extends. 

Trigger digits occur as the likely result of a size discrepancy between the flexor tendon and the tendon sheath, specifically, the A1 pulley. Both the tendons and the pulley undergo changes that can lead to pain and functional impairment in the involved digit(s) and hand.

Trigger digits often present in isolation, however are frequently seen in patients with diabetes mellitus, rheumatoid arthritis, or other rheumatologic conditions.

Patients generally present with pain and “locking, catching, or popping” of the affected digit. A nodule or lump may be felt within the tendon (or palm) at the region of the A1 pulley. Applying pressure over this nodule may cause tenderness and may exaggerate the triggering.

Treatment of trigger digits includes both non-surgical and surgical methods. Non-surgical methods include observation, nonsteroidal anti-inflammatory medications (NSAIDs), corticosteroid injections, and splinting. Surgical treatment involves release of the A1 pulley.