The fabrication of custom skull implants offers a major advance in the treatment of many aesthetic skull deformities. Historically skull augmentation had to be done using a long and complete coronal scalp incision and resultant scar for access and intraoperatively shaped bone cement materials. But today’s custom skull implants allow for the shaping of the implant to be done beforehand and the surgical incision needed to place it less in length.
But whether the surgical incision is small or long, the need to precisely place the implant remains the same. While custom skull implants have an exact fit due to their design, the surface of the skull most of the time is fairly convex and smooth. So even a custom skull implant can slide around and its exact fit may be uncertain.
One method to lessen the risk of a custom skull implant is to have a marking method placed into it. I have found that a simple vertical and horizontal line etched into the implant at its most central location helps provide orientation. The vertical or sagittal line makes sure that it’s anteroposterior placement is correct. The horizontal or coronal lines provides another method to check on the implant’s orientation. Both the horizontal and vertical line together, like a compass, help get the implant placed correctly as it slides around on the skull’s surface.
Once the custom skull implant is satisfactorily placed, it is secured with two small self-tapping 1.5mm titanium screws. They are placed on each side of the implant to prevent rotation. While I always place perfusion holes through any skull implants, which ultimately provides solid implant fixation, that is a process that takes weeks. The screws maintain implant position until then.
Even custom skull implants can create uncertainty as to their exact placement due to their being a long curved shaped implant on a smooth surface. Preoperative etched markings on the implant provide a simple but effective method of replicating on the patient the preoperatively designed skull implant placement.
Dr. Barry Eppley
Indianapolis, Indiana