Presentation
Mother said that right thumb of her infant stuck in flexion and the infant couldn't extend it without mother's help. Passive extension is painful. Examination revealed trigger finger of infant's right thumb.
Patient Data
Transverse ultrasound scan of infant's right thumb (in comparison to left one) revealed focal thickening of flexor pollicis longus (FPL) tendon opposite head of metacarpal bone.
A. Transverse scan of left FPL tendon opposite head of metacarpal bone.
B. Transverse scan of right FPL tendon opposite head of metacarpal bone.
The right FPL tendon is thickened in comparison to the left (circumference of 1.06 cm compared to 0.85 cm).
Case Discussion
Congenital trigger thumb is thought to occur due to thickening of the flexor pollicis longus tendon. In severe cases, such as this one, it can cause a fixed flexion deformity of the thumb.
Treatment can be conservative with finger stretching exercises, or surgical.