Custom skull implants are the most effective method for a wide variety of head augmentations. Made from the patient’s 3D CT scan they are preoperatively contoured to the shape of the skull to allow for the amount of head shape increase that the overlying scalp will permit. One of the important components of their design is that the amount of surface area coverage needed is much greater than one would think. As the point of maximum projection increases so must the surface area around it to maintain a low convexity shape that looks natural.
When skull implants are placed they are done so with small scalp incisions through which a large subperiosteal pocket is created. Like implants placed in the body there are always concerns about their postoperative positional stability. Skull implants are unique in this regard because of the overlying naturally tight scalp cover and the usual large size of the implant. Once positioned the skull implant’s position is usually tight with seemingly little room for movement. Small fixation screws are typically used but this is just for secondary assurance that no postoperative movement will occur.
But one other unappreciated fixation technique that I use in custom skull implants that has multiple purposes is that of perfusion holes. There are 4 to 5mm full-thickness holes placed into the implant prior to placement. As many as 35 to 40 such holes may be placed in an implant. These are called perfusion holes because they will allow fibrovascular tissue ingrowth through them, re-establishing some autogenous connections between the scalp and the bone. This version of induced macroporosity also creates a firm fixation of the implant, each hole acting a bit like a screw. Such holes are easily seen in a 3D CT scan.
Dr. Barry Eppley