Pediatric ortho problems in India: Trigger thumb

Tuesday 15 April 2014

Trigger thumb

CONGENITAL TRIGGER THUMB

Introduction

It is tenosynovitis of flexor pollicis longus with stenosis at A1 pulley. It simply means the tendon meant for bending the thumb is swollen and finds itself difficult to glide in its tunnel because of a smaller tunnel entry. Though this condition is congenital but usually diagnosed later. It must be differentiated from contractures in Arthrogyrposis and spastic thumb in Cerebral palsy.

Its incidence is 2-3 for every 1000 births. It presents as a bent thumb which sometimes becomes straight when forced but with a sudden release. A small swelling can be noted ocasionally at the base of thumb which is called Notta nodule. It is due to ganglion or cyst formation along the tendon near the metacarpal neck. It is also seen bilaterally in many cases.

Natural history

Most cases get resolved spontaneously with age. If the triggering doesn't resolve by 3years or if thumb is not extending then surgical intervention is necessary to prevent permanent deformity.

Diagnosis

Clinical examination is sufficient for a diagnosis. Presentation gets delayed till child is 6months to 1 year.

Management

Initially stretching might help but if it fails to resolve then surgery is gold standard. If not corrected by the age of 3 years spontaneous resolution is not expected to happen. The procedure involves release of A1 pulley. There is no evidence that meddling with the nodule or cyst helps. Care must be taken to protect digital nerves to thumb especially the radial one. Sometimes a hyperextension develops after a late release, in such cases proximal advancement of volar plate at PIP joint with A1 pulley release works well.