Cadaveric Study of a Z-Plasty Modification to the Moberg Flap for Increased Advancement and Decreased Morbidity.

Abstract

The Moberg advancement flap is a well-established tool to provide sensate, vascularized tissue for thumb reconstruction. Modifications providing additional length have been described, but no studies have examined how much additional advancement can be achieved consistently, and at what cost. The authors hypothesized that Z-plasty modification at the base of the Moberg flap would allow additional advancement compared with the traditional technique, and maintain primary closure of the donor-site and avoid additional morbidity. Standard Moberg flaps were performed and advancement was measured on 20 cadaver specimens. Ten flaps were then modified with the O'Brien technique of incising proximally and skeletonizing the neurovascular bundles. The other 10 flaps were modified with Z-plasties at the base of the thumb. Differences in distance of advancement were compared, as was the ability to primarily close donor sites. Average advancement for Moberg flaps was 7.3 ± 1.2 mm, compared with 15.0 ± 2.5 mm for the O'Brien modification (p < 0.01) and 11.3 ± 1.7 mm for the Z-plasty modification (p < 0.01). Although the O'Brien modification allows approximately 50 percent further advancement than the Z-plasty modification compared with the standard Moberg flaps, the increase correlates to a large area of exposed neurovascular bundles at the volar base of the thumb, which requires secondary coverage. However, all Z-plasty donor-sites could be closed primarily. Primary closure of all donor sites will decrease healing time, wound complications, digital nerve sensitivity, and cosmetic appearance. This study is the first to show a significant increase in Moberg flap advancement using Z-plasty lengthening at the thumb base while avoiding any increased morbidity.