The use of custom skull implants has made a wide range of aesthetic head shape changes possible. Using 3D scans and design software implants can be designed for any skull surface(s) to create the desired effect. Such skull implants are far larger than any type of facial implants and their introduction through scalp incisions must be carefully planned.
While the use of large coronal scalp incisions may be how much of reconstructive craniofacial surgery is performed, such an approach is not really acceptable in an aesthetic surgery. This is particularly pertinent if the patients are males with thinning hair, short hair or shaved heads. Thus the scalp incisions for the placement of custom skull implants must be done as small as possible but yet large enough to still get the implant through it. To keep the scalp incision limited one has to sometimes consider modifying the implant to do so.
The most common method to insert a skull implant is to use its elastic deformation property which is inherent in silicone materials. By folding a skull implant they can be inserted through incisional lengths that are less than half of their base diameter. But this does not work for all skull implants once they reach a certain size and/or thickness.
An alternative strategy is to section the implant into two pieces which makes each piece easier to insert. The implant is then effectively halved which can allow the elastic deformation of it to be used. How the split is done in terms of exact geometry does not matter. Any interlocking pattern is far superior to a midline split where how they may come back together is not assured.
Once both pieces are inside the scalp pocket they are reassembled into a single implant again. The key to successfully doing so is to create a non-linear split in an irregular geometry at either one or two places through the implant. The interesting aspect of the geometric split is that it comes back together in a near snap fit manner. It does so because the overlying scalp is tight and once the two pieces get close pushing on the scalp externally will make them pop back together again.
One of the important aesthetic skull reshaping principles, beyond just that of implants, is to limit the tradeoff of the scalp scar to do so. Sectioning the implant into smaller pieces is one approach accomplishing that goal.
Dr. Barry Eppley