Trigger thumb is a condition related to the flexor tendons and pulleys of the thumb where a person has difficulty bending or straightening the thumb. There are two types of trigger thumb. Paediatric trigger thumb occurs in the first weeks or months of life. Acquired adult trigger thumb occurs in adulthood. Another medical term for trigger thumb is stenosing tenosynovitis.
Acquired trigger thumb is the same as trigger finger. For further information on acquired trigger thumb please see our article on trigger finger. The remainder of this article is about paediatric trigger thumb.
Definition
Paediatric trigger thumb used to be known as congenital trigger thumb, however it is now understood that it is a condition that develops after birth and therefore is not congenital. It usually occurs in the first 12 months of life, however can occur up to 5 years of age.
Causes
The reason that trigger thumb occurs in children is not fully understood. There are no known risk factors, there is no genetic predisposition and it is not known to be related to any other conditions. We know that it happens in about 3 out of every 1,000 children and in about 25-30% of cases it occurs in both hands.
The tendon that allows us to bend our thumbs runs down the front side of our thumb. In order to keep it running alongside the bones of our thumb, it passes through a series of pulleys which are tight tunnels of tissue. The tendon has to slide back and forth through these pulleys whenever we bend or straighten our thumbs. In paediatric trigger thumb, the tendon sometimes grows quicker than the pulley can expand and so the oversized tendon has trouble sliding through the pulleys. The pulley that is most often affected is the A1 pulley at the base of the thumb.
Signs & Symptoms
Paediatric trigger thumb can be diagnosed from a physical exam, further imaging is not necessary. In most cases of paediatric trigger thumb, the tip joint of your child’s thumb will be stuck in a bent (flexed) position. Sometimes it can straighten under pressure or after a good stretch.
Unlike adult trigger thumb, paediatric trigger thumb is not usually painful and there is not usually locking and catching.
Treatment
The majority of paediatric trigger thumb cases will resolve with stretches and custom splinting, as these help to get the tendon gliding through the pulley again. Sometimes your child may need some help re-learning how to bend and straighten the joint in eating and play, as they may have adapted to using the hand with a bent thumb. Normally, play therapy is enough to achieve this but sometimes special splints are required.
If your child’s trigger thumb doesn’t improve after a period of the above treatment, then a review with a surgeon may be necessary. The surgeon may recommend a minor surgical procedure to release the A1 pulley and allow the tendon to slide freely. This surgery is quick to recover from and does not lead to any weakness or dysfunction later in life.
Prevention Of Trigger Thumb
Paediatric trigger thumb cannot be prevented but it can be managed safely and easily.
Melbourne Hand Therapy Can Help You
Our therapists will be able to assess your child’s thumb and determine an appropriate treatment plan. In the majority of cases your child’s condition can be managed by our experienced therapists with custom made splints, stretches and play therapy. If required, we can help to organise an opinion from one of our hand surgeons.
