Trigger thumb

Stenosing tenosynovitis to the thumb - 'trigger thumb' - is a result of a mismatch between the size of the flexor pollicis longus tendon and the flexor sheath it traverses. The tendon cannot glide freely resulting in a difficulty extending the flexed thumb. A nodular thickening of the tendon may be felt at the base of the metacarpophalangeal joint.

Treatment entails the open surgical division of the A1 pulley thickening of the sheath. Care must be taken to avoid the radial digital nerve to the thumb which crosses the metacarpal head at the level of the pulley.

Reference

1. David M, Rangaraju M, Raine A. Acquired triggering of the fingers and thumb in adults. BMJ. 2017 Nov 30;359:j5285