Page 112 - Clinical relevance of current materials for cranial implants

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Chapter 5
Time to cranioplasty
Figure 2 gives a schematic overview of the management until final PEEK cranioplasty.
Twenty-two (55%) out of 40 autologous bone grafts were replaced, 6 of them at the time of craniectomy and 16 of them in a delayed fashion after preservation at -80°. These bone grafts failed due to infection (n = 11) or resorption (n = 11). Ten of the 11 infected bone grafts were treated with debridement and delayed cranioplasty. Ten out of 11 bone graft failures due to resorption were treated with immediate cranioplasty.
Eighteen (45%) of the 40 autologous bone grafts could not be replaced due to damage caused by trauma (n = 11), the presence of intra-osseous tumor tissue (n = 4), brain swelling or hemorrhage (n = 3). In two of these 18 cases, PMMA was used for reconstruction of the defect at the time of craniectomy. These implants failed due to a subcutaneous CSF collection. Two PSIs were placed at the time of craniectomy with removal of an intra-osseous tumor (meningioma) and 14 PEEK cranioplasties occurred in a delayed fashion.
The median interval between previous surgery and PEEK cranioplasty was 4.7 months (IQR 0-7.7). The mean number of surgeries prior to PEEK was 1.9 ± 1.1 (median 2.0, range 0-4). In 25 cases (63%) the implant sites were considered complex because more than one surgery was performed prior to PEEK cranioplasty.
Surgery-specific characteristics
The average cranial defect measured 106.3 ± 46.1 cm2 (range 11-181). The largest craniectomy defects were found in stroke patients and after severe brain trauma. The operative field was shaved in 63% of surgeries. The previous scar was fully reused in 88%. An additional incision was made in 13% with a new incision in 8% and a partial reuse of the scar in 5%. In 50% of cases the temporal muscle was suspended to the PSI. A subgaleal drain was placed in 55% of the surgical procedures. The mean operation time was 126 ± 60.4 minutes (median 111, range 40-337).