Page 152 - Clinical relevance of current materials for cranial implants

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Chapter 7
Reported infection and exposure rates reported range from 0% by Lipa et al., up to 14,6% by Chao et al., 25% by Sosin et al., and 38% by Afifi et al.15,40,41,43. Among these studies cranioplasty materials differed. If risk factors, such as radiotherapy or infection are present, some authors advise against the use a one stage free flap reconstruction with alloplastic material because of potentially higher recipient site complications41. Chao et al., did not find preoperative or post-operative radiation to be associated with development of recipient site complications. However, in patients with a history of infected cranial bone or alloplastic cranioplasty, they did recommend a staged approach with direct free tissue transfer alone and subsequent delayed calvarial reconstruction. The average interval between soft tissue and bone reconstruction was 6.0 ± 1.8 months. Atrophy of the LD flap did not limit the ability to perform a delayed cranioplasty, and no difficulty was experienced in flap elevation from the underlying dura40.
Nowadays, with the use of CAD-CAM techniques, preoperatively the resection outline can be marked keeping a safe margin to the tumor and a resection template can be manufactured. During the operation the resection template can be positioned and fixed accurately to the skull guided by navigation. This helps the surgeon to follow the planned resection outline and results in a highly accurate and predictable resection of the tumor which may potentially minimize future recurrences. The PEEK cranioplasty implant can be designed accordingly to the shape of the predicted defect and allow a perfect fit56. Because of the non-bioactive nature of PEEK it will not securely adhere to the surrounding bone. To improve the stability of the cranial implant a good edge contact is necessary. A sawing edge of 45 degrees during the craniectomy would allow the eventual implant (also with a 45 degrees edge) to be supported across the entire bone-implant contact surface. Such design features could easily be incorporated in the preoperative design phase.