How Is The Material Fixed To The Skull In Cranioplasty?
Q: Dr. Eppley, I am looking at building up the back of my head. In reading your blogs you say that you usually add about 60 grams of material. But I don’t know how that would look and whether that is enough. I went on with my experiments, but rather than water I used plasticine which conveniently has a density close to PMMA, to check the volume. I adapted it to the back of my head like an implant would be, and as you said the change is bigger than one would expect (I tried 60g and 80g). So if the trade-off for a bigger volume is ‘longer or more full coronal incision’, could you tell me what would be its size and location for 60g and 80g? (I’m not sure I’ve read around 10 centimeters for 60g on your blog) As a side question, how would you attach the implant to my skull?
A: That is a clever way to see how much volume 60 grams of cranioplasty material is. Remember that it will also look bigger than you think when placed under the scalp skin. To get this amount of material on the back of the skull, an incision of 14 to 16cms long is usually needed. Onlay cranioplasty materials are fixed to the skull by first applying small screws to the skull bone allowing them to set up about 3 or 4mms above the bone. When the material is then applied this gives it something to hang onto to like rebar used in concrete. While screw fixation may not be absolutely necessary for augmentative skull reshaping, I prefer it since it is simple to do and adds a bit of security for prevention of implant mobility.
Dr. Barry Eppley