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Congenital Trigger Thumb

Congenital Trigger Thumb

Congenital Trigger Thumb is a condition seen in infants and young children where the thumb becomes locked in a bent (flexed) position and has difficulty straightening. Unlike in adults, where trigger finger or thumb usually develops due to tendon irritation from overuse, congenital trigger thumb appears during early childhood, often within the first few years of life. It is sometimes also referred to as pediatric trigger thumb.

Although termed “congenital,” meaning present at birth, the condition is not always visible in newborns. In many cases, it becomes noticeable only after the child begins to use their hands more actively, usually between the ages of 1 and 3 years.

Anatomy and Mechanism

The thumb moves smoothly due to the coordinated action of muscles, tendons, and pulleys. The flexor pollicis longus (FPL) tendon is responsible for bending the thumb. This tendon passes through a sheath reinforced by pulley-like structures that keep it close to the bone.

In congenital trigger thumb, the A1 pulley at the base of the thumb becomes tight or thickened, or a small nodule (called a Notta’s node) forms on the tendon. As a result, the tendon cannot glide smoothly through the pulley system. This leads to catching, clicking, or locking of the thumb in a bent position.

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Causes and Risk Factors

The exact cause of congenital trigger thumb is not fully understood. Unlike in adults, it is not associated with repetitive strain or systemic diseases. Possible contributing factors include:

  • Developmental anomaly in the tendon or pulley system.
  • Genetic predisposition, as the condition can sometimes run in families.
  • Intrauterine positioning or minor trauma during early development may contribute, though not proven.

It affects boys and girls equally and usually appears in one thumb, though in 25–30% of cases, both thumbs may be affected.

Clinical Features

Parents often notice signs of congenital trigger thumb during routine activities. The main features include:

  • Thumb locked in a bent position – The child is unable to fully straighten the thumb at the interphalangeal (IP) joint.
  • Triggering or clicking – In some cases, the thumb catches or pops when moving from bent to straight.
  • Presence of Notta’s node – A small, palpable lump may be felt at the base of the thumb along the flexor tendon.
  • Pain or discomfort – Usually mild, but some children may complain of pain during thumb movement.
  • Functional limitation – Difficulty grasping large objects or using the thumb for pinching activities.

In severe or untreated cases, the thumb may remain permanently bent, leading to joint stiffness.

Diagnosis

  • The physician observes the child’s thumb position and range of motion.
  • A small nodule at the base of the thumb is often detectable.
  • The thumb may snap or lock when attempts are made to straighten it.
  • X-rays are usually not necessary unless other conditions need to be ruled out.

Treatment

1. Non-Surgical Management

  • Observation: In infants under 1–2 years, if the thumb can still be passively straightened, doctors may recommend watchful waiting, as spontaneous recovery is common.
  • Splinting or stretching exercises: A thumb splint may be used to keep the thumb extended, combined with gentle stretching exercises taught to parents.
  • Massage and physiotherapy: Some specialists suggest soft tissue massage around the tendon sheath to encourage smooth gliding.

2. Surgical Management

  • Trigger thumb release (A1 pulley release): This is a minor procedure performed under anesthesia. The surgeon makes a small incision at the base of the thumb and releases the tight A1 pulley, allowing the tendon to glide freely.
  • The surgery has a high success rate (over 95%), with low risk of complications.
  • Recovery is usually quick, with children resuming normal thumb use within a few weeks.

Complications

  • Permanent flexion deformity at the thumb joint.
  • Joint stiffness and reduced range of motion.
  • Functional impairment in activities requiring thumb extension.
  • Psychological or cosmetic concerns for parents and child.

Surgical treatment is generally safe, but possible risks include infection, scarring, and very rarely, injury to nearby nerves or blood vessels.

Prognosis

The prognosis for congenital trigger thumb is excellent. Many children recover fully either through spontaneous resolution or after surgical release. Once treated, recurrence is rare, and long-term hand function is normal.

Prevention

There are no specific preventive measures since congenital trigger thumb is a developmental condition rather than one caused by external factors. Early recognition by parents and prompt medical evaluation ensure the best outcomes.

Conclusion

Congenital trigger thumb is a relatively common condition in young children characterized by locking or inability to straighten the thumb due to tendon entrapment at the A1 pulley. While some cases resolve naturally in the first two years of life, persistent cases often require surgical treatment, which has an excellent success rate. Early diagnosis and management are important to prevent long-term deformity and functional limitations. With timely care, children with congenital trigger thumb can achieve full recovery and normal hand use.

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