Functional and Cosmetic Reconstruction of Floating Thumb: A Thumb-preserving Technique

For the severely hypoplastic thumb, including floating thumb, it is difficult to acquire function while preserving the thumb. Pollicization using the index finger after removing the hypoplastic thumb is usually indicated for such cases. However, most parents of children undergoing surgery for deformed hands desire retaining the digit number, 1 thumb and 4 fingers. A floating thumb has a neurovascular band in its pedicle, and we can identify and divide the band with precision for preservation, although it seems impossible to retain it. For acquiring function while retaining the thumb, we developed carpometacarpal arthroplasty of the floating thumb. For the first stage, the fourth metatarsal head was transferred to the first metacarpal base, followed by third metatarsal half-slip transfer to the space of the excised fourth metatarsal head with the first web plasty using a dorsal sliding flap. Second stage surgery was performed ∼6 months after the first stage. For creating stable opponensplasty, the abductor digiti minimi tendon was anchored to the ulnar side of the metacarpophalangeal joint; for extension, extensor indicis proprius transfer to the hypoplastic extensor pollicis longus tendon was performed; for flexion, ring finger flexor digitorum superficialis transfer to the hypoplastic flexor pollicis longus tendon was performed. In general, the functional results were acceptable with a high degree of family satisfaction, although in some cases function was limited to simple object holding. We explain the surgical procedures to preserve the thumb while gaining function as well as appearance using high-quality illustrations, figures, and videos. This should be helpful for surgeons who want children with hypoplastic thumbs to have both 5 digits and reasonable functional ability.