Revista de informes de casos clínicos

Thumb Hypoplasia Type IIIA: A Case Report

Abstract

Phan Duc Minh Man, Nguyen Duong Phi, Mai Trong Tuong, Nguyen Vo Dang Khoa and Truong Quang Dinh

Thumb hypoplasia occurs in a variety of forms, which are often categorized using Blauth classification and its modifications. In 1991, Manske et al. suggested a type IIIA variation characterized by first web space narrowing, underdeveloped or absence of thenar muscles, thumb extrinsic and metacarpophalangeal joint instability. Here we present a 5-year-old female patient who visited our clinic due to a small thumb and inability to flex the interphalangeal joint since birth. Her medical history showed an esophageal atresia surgery which was performed when she was a neonate. She then underwent a first web space release using four-flap Z-plasty and exploration of the flexor pollicis longus tendon. We found that the extensor pollicis longus and flexor pollicis longus tendon were interconnected along the radial border of the thumb, traction on either tendon tends to abduct the thumb at the metacarpophalangeal joint. Tenolysis was performed and the patient showed significant improvements in opposition movements and precision grip post-operation. We proposed that ultrasound is as reliable as magnetic resonance imaging to examine the flexor tendon and performing a wrist incision to confirm the recovery of the thumb opposition motion can save unnecessary tendon transfer.