What is it?

Trigger thumb is a condition where the thumb is locked in the flexed position at the Interphalangeal Joint (IP joint). Sometimes, the thumb can be forcibly extended with a palpable or audible click. Sometimes, it is locked in acute flexion and cannot be extended. The condition may be familial (runs in the family) and is bilateral in 50% of cases.

Trigger thumb is due to thickening and constriction of the fibrous flexor sheath the surrounds the Flexor pollicis tendon at the base of the thumb. The constriction does not allow for free movement of the tendon within the sheath. This causes the thumb to be stuck in the flexed position.

What does the doctor do about it?

The condition may present at birth, or during infancy. Treatment is often conservative. Parents are taught to stretch the thumb and gently extend the thumb, even in the thumb that is locked in flexion. Over a period of 18 to 24 months, the triggering may resolve spontaneously. In cases where the thumb is locked in acute flexion and does not allow any extension, surgical release of the fibrous flexor sheath is indicated by age 2 to prevent permanent contracture.