Treatment of thumb soft-tissue defects using a bipedicle island flap of the index finger: anatomical basis and clinical application

Abstract

Reconstruction of the thumb with exposure of bone and tendon is challenging. We designed a bipedicle island flap from the dorsum of the index finger to repair thumb defects. One pedicle includes the radial proper palmar digital artery (PDA) of the index finger, another pedicle includes the first dorsal metacarpal artery (FDMA). The aim of the study was to investigate the anatomical basis and clinical application of this flap. Eleven fresh cadaver hands were dissected, the FDMA and the radial proper PDA were exposed. Their origin, distribution and diameter in different locations, especially in the dorsum of the proximal phalanx of the index finger, were examined. Ten patients (11 hands) underwent thumb reconstruction using this flap. During follow-up, the flap survival and hand function were evaluated. The origin of the FDMA in three cadaver hands was abnormal. The FDMA was mainly distributed in the proximal area of the dorsum of the proximal phalanx. The radial proper PDA of the index finger formed one constant dorsal branch, mainly distributing in the middle and distal area of the dorsum of the proximal phalanx. All flaps survived. At follow-up, the span of the first web and the range of motion of the thumbs and index fingers reached more than 94% of the contralateral finger. All patients were satisfied with the hand function according to the Michigan Hand Outcomes Questionnaire (MHQ). The bipedicle island flap has two arterial systems to provide sufficient blood supply. This technique provides another option for thumb reconstruction when a large supercharged FDMA island flap needs to be designed, or when there is an additional injury to the radial side of the dorsum of the hand or if there are anatomical variations of the FDMA, or if damage to the FDMA occurs during surgery.