How Much Material Is Needed For My Predicted Skull Augmentation Result?

Q: Dr. Eppley, I am interested in surgery to improve my skull shape, I would just like to clarify some things first. You mentioned 60 grams of PMMA to obtain the predictive image results which would indeed be quite good for me. However I’m wondering if this quantity would be enough to make this aesthetic difference. Indeed I’ve read that PMMA has a density around 1.2 g/cm3, thus 60g of PMMA would have a volume around 50cm3, which seems to be quite small (I checked with 50g of water).As you’re quite experienced with skull aesthetics, do you think this would be enough in my case, and are you positive that the predictive image is obtainable? Maybe it would be preferable for me to have a first stage to stretch the skin, then have a bigger implant inserted? Please excuse my uncertainty, I’m trying to find the best option I have. I have seen one of your skull reshaping surgeries on your blog of a 42y old man with a flat spot much like mine. Do you remember what kind of surgery he had? Thank you for your help and advice.

A: I can certainly appreciate your volumetric computations of the biomaterial mass. But one aspect of that assessment that is missing is how any implanted volume of material translates into a change in external appearance. One thing I have learned over the years is that small volumes can usually make a much bigger change that one would think in many cases. In other words, one can easily be fooled in seeing how something looks in your hand than when it is implanted in the human body. The use of 60grams of PMMA in skull augmentation is usually the upper limit of how much the scalp can stretch over a skull augmentation without undue tension.  With longer or more full coronal incisions, one may be able to get up to 90 grams of material implanted as the scalp flaps are more fully mobilized. In your case, I would much rather take this approach as I do think that somewhere in the 60 to 90 gram material range should be more than adequate to achieve the predicted result. The patient to which you refer in the blog had 25 grams of PMMA implanted for that unilateral occipital skull augmentation result.

Dr. Barry Eppley