Neurovascular Island Flap for Pulp and Nail Augmentation in Hypoplastic Thumb Duplication Reconstruction

Abstract

Objective: Pulp and nail asymmetry is commonly seen in thumb duplication condition, particularly when both digits are significantly hypoplastic. Conventional or modified Bilhaut-Cloquet procedure can help to restore the symmetry but very often results in a major dorsal scar leading to cosmetic imperfection. The authors introduced a neurovascular island flap for pulp and nail augmentation, and combined with a dorsally based skin flap approach, to improve the aesthetic result in thumb duplication reconstruction. Materials and Methods: Eight patients, including 1 Wassel type II, 1 Wassel type III, and 6 Wassel type IV, were operated on between 2002 and 2010. The contralateral thumbs are all normal. All patients had significant hypoplasia and asymmetry of the pulp and nail of the planned retained digit. The average age of operation was 12 months (range, 8-15 months). A dorsally based skin flap centered on the site of bifurcation was raised for exposure and dissection of the abnormal structures. A neurovascular island flap, including part of the pulp tissue, nail bed, with or without the associated phalangeal bone, was raised from the planned ablated digit based on its single neurovascular bundle. After the standard procedure of ablation, ligament, and musculature reconstruction, with or without realignment osteotomy, the island flap was transferred to the proper digit with meticulous repair of the nail bed, nail fold, and pulp tissue using fine sutures under magnification with operating microscope. All patients were followed up with to monitor the aesthetic, functional, and radiological outcome. The average follow-up was 80 months (range, 25-120 months). An aesthetic scoring system was proposed to assess the cosmetic results of the thumb duplication reconstruction. Results: All flaps survived, with transient intraoperative ischemia of the transferred pulp in 1 case. The major portion of the surgical scar lied toward the volar aspect of the thumb, leaving the cosmetic dorsal aspect relatively intact. Pulp and nail fold symmetry was improved in all cases. The nail width discrepancy reduced from 25.2% preoperatively to 4.6% at final follow-up. The hypoplastic appearance of the pulp was improved in all cases. The pulp circumference was comparable with the contralateral normal thumb, with average pulp circumference discrepancy of 6.8% (range, 1.7%-13.0%) at final follow-up. Nail ridges were moderate in 2 early cases, minimal in 3 cases, and inconspicuous in 3 cases. Surgical scar was not obvious in all but 1 case. The proposed aesthetic scoring system was able to assess and highlight the cosmetic aspect of the outcome and correlated well with the parents’ satisfaction. Conclusions: In selected cases of thumb duplication with significant pulp hypoplasia and nail asymmetry, the neurovascular pulp and nail island flap is a safe and effective mean to restore symmetry for better aesthetic improvement.