This is a condition where an abnormal bend in the thumb is observed by the parents. The cause is an abnormal swelling called ‘Notta’s nodule’ which is present at the base of the thumb in the flexor pollicis longus tendon. This swelling gets stuck in another ligament called A1 Pulley in the flexed position as shown.

When the fingers are small this nodule easily slips through the A1 pulley but as the age becomes one year this symptoms start to appear. The treatment is stretching and splintage to start with, but as the symptoms get stuck surgical release of A1 pulley is done.