Background: There are many procedures that can be done to rebuild the skull including bone replacement and external bone reshaping. (cranioplasty) With today’s computer technology large segments of the skull can be replaced by a variety of materials including HTR, PEEK and PEKK materials. While there are surgeon advocates for all of these materials, I have used all of them and they all offer excellent clinical outcomes. Their handing properties do differ and that must be considered in each patient for their particular skull reconstruction needs.
A computer-generated skull implant is intended for full-thickness bone defects. Whether it be a small or very large full-thickness skull defect, there is no better alternative for skull replacement in adults than the use of a computer-designed implant. The larger the skull defect the more relevant the use of a premade implant becomes.
There are very few cases of the need for a prothetic total skull implant. This would necessitate the loss or removal of the entire skull. Such is the following case and it illustrates that, while the entire skull can be replaced, that does not end the need for further reconstruction efforts. The perimeter of the skull has various tissue attachments which likewise need to be rebuild to complete a total skull reconstruction result.
Case Study: This 44 year-old male came with a history of having undergone a total skull removal with subsequent total skull prosthesis placed. (PEEK material) The exact reason his total skull removal came from failed attempts at reconstruction of a congenital sagittal craniosynostosis condition. While his entire skull was replaced by a computer-designed prosthesis, the shape of the implant and the accuracy of its fitting into the remaining skull base its base was less than ideal. He had a very narrow and long head shape and he has complete temporal hollowing and ears that stuck out due to loss of soft attachments.
Under general anesthesia his first operation consisted of removal of his existing skull implant. This was quite challenging due to the hardness of the PEEK material and the tissue ingrowth through its perfusion holes. A new computer-designed total skull implant made of PEEK material was design and placed that had a better shape. Its anterior-posterior length was reduced and shape across the top of the head was more natural.
While his revised total skull implant surgery was successful with a much improved head shape, he required three subsequent surgeries to create a more appearance. These procedures included fat injection temporal grafting, further only cranioplasties using PMMA material on top of his skull implant, revision of his T-shaped scars and ear setback surgery. (otoplasty) In the end her was able to achieve a much more natural looking head shape.
When the total skull is removed, there is loss of all the muscular attachments in the temporal region. This results in severe temporal hollowing, thinning at the sides of the head above the ears and ears that will stick out. Surprisingly injection fat grafting worked to correct the severe temporal hollowing. This was unexpected given that there was only skin stuck down to the skull prosthesis. Cranioplasties adding additional material on top of the implant was used to help create any deficiencies that the implant did not achieve. Correcting the ears became necessary as the postauricular muscle attachments had been lost allowing the ears to fold forward.
Highlights:
1) Total skull reshaping or reconstruction is a rare procedure that requires several stages to optimize the head shape.
2) The entire skull above the level of the ears can be safely (and only) replaced with a implant made from a 3D CT scan.
3) While the skull can be replaced, the surrounding soft tissue attachments must be considered in the overall skull reconstruction effort.
Dr. Barry Eppley
Indianapolis, Indiana