We occasionally get a referral through for a child with a trigger digit – frequently thumbs. Paediatric trigger thumb, also known as paediatric acquired thumb flexion contracture, occurs in children aged between 1 and 4 years of age, has an incidence of 1-3:1000, and has been linked to a genetic predisposition.
The pathophysiology is largely still unknown, however research has shown an anatomical mismatch of the flexor pollicis longus (FPL) tendon in the tendon sheath and fibrous tissue proliferation of the A1 pulley.
The child often presents with a thumb locked in flexion at the IP joint. Notta’s nodule, a palpable nodule on the volar aspect of MCP joint flexion crease may be present. Often pain free unless the thumb is forcibly extended. Ultrasound scan may show abnormality of FPL or A1 pulley.
Differential diagnosis should be considered and includes: Congenital clasped thumb and thumb in palm deformity resulting from Cerebral palsy or arthrogryposis, fracture, or dislocation of thumb, and Notta’s nodule can be mistaken for a bony mass.
Conservative management has been shown to be a successful method of management particularly for grade 1 and 2 trigger thumbs. Treatment includes splinting, passive stretches and tendon gliding exercises. A referral for surgical review may be warranted for those that do not respond to conservative management or those with a grade 3 trigger thumb on diagnosis.
References on request