Significant brow bone reduction requires more than a burring technique. The thickness of the bone over the frontal sinus is too thin to permit more than a few millimeters of brow bone reduction. A bone flap setback technique is the definitive brow bone reduction method. By removing the entire bone cover over the frontal sinus it can be shaped and set back in after the perimeter has been similarly reduced. Reductions of 5 to 7mms or more are then obtainable.
To fully visualize the brow bones for the surgery the traditional access required is a full coronal scalp incision. This allows all the soft tissues of the forehead to be lifted off and the bottom side of the brow bones directly visualized. In this manner the bone cuts around the perimeter of the brow bone can be clearly seen and made.
The coronal scalp incision, however, can be aesthetically unappealing in certain patients such as in men and some women where hair camouflage may be more limited. For those patients I have used the ‘window’ technique for brow bone reduction which avoids the need for a superior incision that has to extend down into the low temporal region. This can be done using an incision at the edge of the frontal hairline (pretichial) or one or two centimeters behind the frontal hairline. The forehead flap is then lifted up to allow full subperiosteal release over the central and lateral brow bones down to the frontozygomatic suture line.
Looking down from above the right and left supraorbital neurovascular bundles can be isolated and protected.
Through this superior exposure a reciprocating saw is used to make a full thickness bone cut into the frontal sinus around the top and sides of the brow bone. The inferior cut is then made by passing osteotomes through the superior bone cut down to inferior internal edge of the brow bone which is used to complete the circumferential osteotomies. The bone flap is then removed. Many times the sinus mucosa is largely intact…even though it is not critically important than it is.
The bone flap is taken and then reduced on its inner and outer surface until it is as flat as possible. Often there will be areas that you can almost see through. A small plate is applied centrally for fixation.
While many believe the reshaping of the bone flap is what creates much of the setback effect, it only makes a partial contribution to the final contour reduction. Once the bone flap is removed the perimeter of the surrounding frontal bone is reduced including the high radix of the nose. To get the bone flap to setback into the reduced perimeter the septum between the paired frontal sinuses must also be reduced.
The bone flap is replaced and inset and secured with a screw through the plate into the intact bone. Usually this is done superiorly by occasionally may be done inferiorly where any risk of plate visibility is zero due to the thicker glabellar soft tissues. All edges of the brow bone flap are covered with a dissolvable collagen mesh before forehead flap closure.
The window technique in brow bone reduction allows for a smaller superior scalp incision to be used and avoids placing it in the temporal region where widening of it almost always occurs. With careful technique the same brow bone and more complete forehead reshaping can be done as with a turndown forehead flap.
Dr. Barry Eppley