Arterial anatomical basis of the dorsal digito-metacarpal flap for long fingers

Several flaps have been described to treat severe soft tissue defects of the finger dorsal side. Many authors studied vascular organization of the hand on its dorsal side; most of them insisted on deep vascularization into the intermetacarpal spaces, which is formed by the dorsal metacarpal arteries. Those dorsal metacarpal arteries are the anatomical support of many flaps, which do not preserve the dorsal interosseous muscles fascias. Only few authors described dorsal vascular organization at the level of the proximal phalanx; however, using a rotation point of a flap distally to the metacarpal head with a donor site on the dorsal aspect of the hand could cover all distal soft tissue defect of long finger. In order to determine the technical limitations of dorsal digito-metacarpal flap procedures, we studied number and location of arterial anastomoses between the reticular subcutaneous dorsal network and the rest of the vascularization at this level, which was formed by the deeper dorsal metacarpal arteries, common palmar digital arteries and proper palmar digital arteries, and between the dorsal digital arteries. Twenty-four long fingers from embalmed cadavers were studied after a reverse flow injection of colored latex and dissected layer-by-layer preserving the digital-metacarpal arterial network. At the level of the hand, the dorsal metacarpal arteries of the third and fourth intermetacarpal spaces were inconstant. When present, two or three arteries anastomosed in star shape with the reticular network. No such arterial anastomosis was observed proximally to the level of the intertendinous connections (junctura tendinorum) that bridge the extensor digitorum communis tendons. When no dorsal metacarpal artery was present, some communicant arteries arose from the common palmar digital arteries. Moreover, all the nutrient branches were more numerous distally to the intertendinous connections (junctura tendinorum). At the level of the metacarpophalangeal joints, the hand cutaneous network was always anastomosed with the dorsal cutaneous network. At the level of fingers, the dorsal cutaneous network was always supplied by four branches arising from the proper digital artery. Our study supported the reliability of dorsal digitometacarpal flaps, supplied by numerous palmodorsal digital anastomoses and by a rich plexiforme network joining the hand skin supply and that of the dorsal finger skin. During the procedure, we recommend limiting the surgical dissection of the flap at the level of the middle phalanx.