A patient with lower extremity reconstruction is presented with a radial forearm free flap designed using the cluster analysis method of cutaneous perforators. The cutaneous vascular anatomy of fasciocutaneous flaps is discussed as well as the application of the mathematical model of analysis of the vascular territories within specific flaps to assist in "custom" flap design. The ultimate goal of this technique is the creation of flaps that provide a more precise and anatomical reconstruction of the proposed defect.