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Reversed venous flow in the distally pedicled radial forearm flap: surgical implications.

In recent years the distally pedicled radial forearm flap has proved to be a versatile technique for resurfacing the hand. The venous drainage of this flap, however, has remained a puzzle. Various explanations have been suggested, including bypass of the valves by collateral veins and by crossover between the venae comitantes. However, venous drainage must be against the direction of the valves in at least one segment of the veins. The question of reversed venous flow and how it may be achieved reliably is addressed in this study. Timmons has postulated three criteria which all must be satisfied for reversal of venous flow. These criteria, namely higher proximal venous pressure, denervation of the valves, and the filling of the venous segments may be achieved satisfactorily if a few precautions are taken and certain technical manoeuvres performed. The criteria were re-examined in the light of known physiological phenomena. In addition, certain pertinent anatomical facts which arose from our cadaveric studies and which may be exploited to advantage are discussed. Our studies have led to greater understanding of reversed venous flow and to greater success with this flap in our clinical practice.