C1333185 -

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If a 5-month-old girl cannot bend her ring finger, possible causes include:

1. Congenital Trigger Finger (Pediatric Trigger Finger)

• Also called congenital tenosynovitis.

• Most common in the thumb but can affect other fingers.

• Caused by a mismatch between the size of the flexor tendon and the surrounding sheath at the A1 pulley.

• The finger may be locked in extension or flexion, and you may feel a nodule along the flexor tendon.

2. Congenital Flexor Tendon Abnormality

• Absence or malformation of the flexor digitorum superficialis (FDS) or flexor digitorum profundus (FDP) tendon.

• Leads to limited or no active flexion of the affected finger.

3. Arthrogryposis Multiplex Congenita

• A condition involving joint contractures from birth.

• Often affects multiple joints, not just a single finger.

• Look for stiffness or contracture in other joints.

4. Amniotic Band Syndrome

• Caused by constriction in utero.

• May result in deformity, hypoplasia, or absent movement of digits.

5. Trauma (including birth trauma)

• Though less common, injury to tendons or nerves during birth or shortly after might result in reduced movement.

6. Neuromuscular Disorders

• Rare at this age for isolated finger involvement, but conditions like brachial plexus injury may contribute.

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Evaluation:

• History: Was the problem noticed at birth? Any trauma?

• Physical Exam: Is the finger stiff, locked, swollen, or hypoplastic? Any palpable nodules?

• Imaging: Ultrasound or MRI may help assess tendon integrity.

• Referral: Pediatric orthopedic or hand specialist is typically involved.

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