 The middle line of the Z-shaped incision (the central element) is made along the line of greatest tension or contraction, and triangular flaps are raised on opposite sides of the two ends and then transposed.The length and angle of each flap are usually the same to avoid mismatched flaps that may be difficult to close.Some possible complications of Z-plasty include flap necrosis, haematoma (blood clot) formation under the flaps, wound infection, trapdoor effect and sloughing (necrosis) of the flap caused by wound tension and inadequate blood supply.