Background: The forehead occupies a full third of the face in both frontal and side views. With such a large surface area there are numerous topographic features which create its shape and appearance. One major aesthetic feature of the forehead is its inclination (FI) often called the slope. As classically described it is the angle of the forehead slope in relation to the Frankfort horizontal line. The forehead slope is obtained by drawing a line from the glabella to the trichion if using external skin measurements. If using bone the forehead inclination line runs between the brow bone projection and the slope of the bony forehead.
The forehead inclination angle or slope differs between the genders with men having a slighter greater backward slope (10 to 12 degrees) than women. (5 to 7 degrees) One factor that affects the angle in men is their brow bone projection. The greater the brow bone projection the greater the slope. Conversely the less brow bone projection the less forehead inclination that is present. It is one but not the only reason women have less of a forehead slope.
In severe male forehead slopes the brow bone can look overly projected. (pseudo brow bone protrusion) Patients and some surgeons may think that brow bone reduction would be the correct treatment choice but this may just be a reflection of what they know how to do. It is important in preoperative assessment to look at both options (brow bone reduction vs forehead augmentation) by prediction imaging in profile to see what looks best to the patient. But as a general rule when the forehead slope is greater than 15 to 20 degrees its correction provides far greater improvement than any amount of decreased brow bone projection. This is simply a matter of the amount of bony surface area change.
Case Study: This male had apparent overly projected brow bones but that only appeared so due to the severe forehead inclination that he had. His forehead inclination angle was 25 degrees with an additional forehead-skull angle of 10 degrees. Even though it was obvious having a very sunken looking forehead prediction imaging showed that forehead augmentation was the most effective forehead reshaping procedure.
A custom forehead implant was designed to decrease his forehead inclination. A very important part of the design is that it must extend further back onto the top of the skull to blend in naturally. Like many forehead implants the design can not stop just at the top of the visible forehead otherwise there would be a profound step off. Also as a male in the front view its shape must be flatter and not round which is best appreciated by color mapping the implant thicknesses.
Under general anesthesia the forehead implant was placed through a small incision behind the frontal hairline.
The immediate intraoperative result showed an impressive change from just a 5mm thick implant of 45cc volume.
When seen after he was well healed the decrease in the forehead inclination change was signifincant and any evidence of brow bone protrusion eliminated.
Forehead slope correction is slaways best done by a custom forehead implant design. It is a large facial surface area and getting it to blend into the top and sides of the head as well as provide control of the change in the slope requires preoperative design control. Its other benefits over the historic use of bone cements is the ability to use a smaller scalp incision for placement as well as have assured smooth contours and edging.
Key Points
1) A severely retroclined forehead can create the impression that the brow bones are overly projected.
2) Male forehead inclinations would be considered aesthetically undesired at greater than 15 to 20 degrees.
3) A custom forehead implant can dramatically change the slope and does in a smooth and manner to the top of the skull as well.
Dr. Barry Eppley
World-Renowned Plastic Surgeon