Geometric considerations in the design of rotation flaps in the scalp and forehead region.

The classical transposition and rotation flaps are well known. Cosmetic considerations in the scalp and forehead region limit the use of a flap design that requires a skin graft for a donor defect. On sound geometric principles, the classical flap designs are suitably modified here to have a somewhat equal proportion of transposition and rotation. This "modified rotation flap" design works to a maximum advantage in the inextensible region of the scalp and forehead by providing single-stage primary closure of moderate to large defects. No backcuts are ever necessary with this flap design. Use of this principle to modify the rotation flap design for closure of an extended midline forehead defect following rhinoplasty allows a still wider (up to 6.5 cm) midline forehead flap to be available for rhinoplasty with primary closure of the donor defect.