Evaluation and Management of Preaxial Polydactyly

Abstract

Purpose of review: To provide a current review of the embryology, classification, evaluation, surgical management, and clinical outcomes related to preaxial polydactyly.

Recent findings: Recent studies include a proposed embryologic link between preaxial polydactyly and other congenital abnormalities, an evaluation of long-term postsurgical outcomes, and an examination of important predictors for postsurgical outcomes. Preaxial polydactyly, while relatively uncommon, is a complex congenital hand abnormality that requires careful preoperative classification and proper surgical intervention timing to yield optimal outcomes.

Keywords: Congenital hand anomaly; Polydactyly; Preaxial; Radial; Split thumb; Thumb duplication.

Fig. 1

a Photograph demonstrating Wassel-Flatt type IV preaxial polydactyly in the left hand of a 16-month-old male. Note the divergence of the radial and ulnar thumbs at the metacarpophalangeal joint and the convergence at the interphalangeal joints. The radial thumb is notably smaller with poorly formed creases along the dorsal aspect of the interphalangeal joint suggesting more limited motion in comparison with the ulnar thumb. Observation of the child demonstrated preferential use of the ulnar thumb. b Photograph demonstrating postaxial polydactyly in the right hand of an 18-month-old female. In this case, the extra digit is well-formed, and there is a bony connection between the ulnar and radial small fingers. In the majority of postaxial polydactyly cases, the supernumerary digit contains primarily soft-tissue elements and is connected to the hand by a thin cutaneous bridge

Fig. 2

Illustration demonstrating the Wassel-Flatt classification system for preaxial polydactyly. Note that the Wassel-Flatt type VII thumb duplication is characterized by the presence of a triphalangeal thumb. (Used with permission from the Children’s Hospital of Philadelphia, copyright CHOP)

Fig. 3

Photograph illustrating Wassel-Flatt type VII preaxial polydactyly in the right hand of an 18-month-old male. Note the abnormally long appearance of the thumb along with the presence of distinct proximal and distal interphalangeal joint creases suggestive of the extra middle phalanx

Fig. 4

Photographs demonstrating the reconstruction of a Wassel-Flatt type IV preaxial polydactyly in the left hand of a 16-month-old male pictured in Fig. 1a. a Zigzag surgical incision along the radial border of the ulnar thumb is used to optimize visualization during surgery while minimizing postoperative scarring. b The radial collateral ligament is detached from the proximal phalanx of the radial thumb (held in this photograph with tissue forceps at the nine o’clock position) with a strip of periosteum and is preserved for reattachment to the proximal phalanx of the ulnar thumb. c The metacarpal head is shaved down with #15 blade to reduce the abnormal breadth of the metacarpal head while preserving the origin of the radial collateral ligament. d A Kirschner wire is used to stabilize the metacarpophalangeal joint for 4 weeks, and the skin flaps are closed with absorbable suture

Fig. 5

Photograph demonstrating a custom forearm-based thumb spica splint with the interphalangeal joint included to ensure proper alignment of the joints and to maintain the web space depth