Page 212 - Clinical relevance of current materials for cranial implants
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                                Chapter 11
Part II: Current evidence
Chapter 2 provides a systematic review of the literature addressing post- operative complications after cranioplasty. All patients in the 228 included studies underwent decompression craniectomy and received an autologous or alloplastic cranioplasty in a later stage. All reported complications were extracted and analyzed. Interpreting the results of this meta-analysis was difficult due to low methodological quality of the included studies and heterogeneity of the outcome measures, in terms of a large variation in surgical procedures, patient characteristics, and outcome definitions. For this reason no ‘superior’ material for cranioplasties could be identified. Infection and resorption were the most frequently reported complications. Autologous cranioplasties were found to have an infection rate of 6.9%, versus 5.0% in alloplastic cranioplasties. Resorption was reported only after autologous cranioplasties (11.3%). Consequently, autologous cranioplasties had to be removed more frequently than alloplastic cranioplasties (10.4% versus 5.1%). It was concluded that the use of autologous cranioplasties should not be encouraged in any circumstance.
Part III: Current challenges
For the development of a new material for cranioplasty, it is important to understand the reasons for failure of the existing materials for cranioplasties. Thus, the advantages and disadvantages of the various materials need to be weighed.
In order to identify the risks of failure of autologous bone flaps, a two-center retrospective study was performed (chapter 3). The included patients (n=254) underwent unilateral decompressive craniectomy. The autologous bone was reinserted in a subsequent surgical procedure. In 52 (20.5%) patients the autologous bone failed; in 24 (9.4%) due to infection and in 23 (9.1%) due to resorption. The associated factors for removal of the autologous bone were 1) the hospitalization time after decompressive craniectomy, the time between decompressive craniectomy and cranioplasty, and the follow-up duration after the cranioplasty. Removal of the cranioplasty due to an infection was associated with having a neoplasm as reason for decompression (29.2% versus 7.8%) and a longer hospital stay after decompressive craniectomy (54 days versus 28 days). Cranioplasty removal because of bone resorption was associated with a younger age (35 years versus 43 years), a larger circumference of the cranial defect (39 cm versus 37 cm) and a longer follow-up after the cranioplasty.

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