Congenital anomaly of the thumb: aplasia of the flexor pollicis longus.

A five-year-old boy, with congenital aplasia of the flexor pollicis longus, without other associated anomalies is reported. A two-stage procedure was done using a silicone rubber rod and pulley reconstruction, followed by transfer of the flexor digitorum superficialis tendon from the ring finger to the distal phalanx of the thumb. This resulted in 0/55 degrees active flexion at the interphalangeal joint.