Page 89 - Clinical relevance of current materials for cranial implants

In the years following the initial cranioplasty the patient had multiple epileptic
seizures; with the use of lamotrigine these did not recur. The patient lived by himself,
was eventually permitted to drive a car, and did not have any complaints. In 2016,
15 years after the initial cranioplasty, he complained about progressive headaches,
memory impairment, poor vision, inability to operate motor vehicles, and unstable
gait. The patient could not recall any trauma involving the cranioplasty. On physical
examination, the cranioplasty was palpable and seemed loose. A computed
tomography scan with 3D reconstruction revealed that the cranioplasty had fractured
into four pieces, which were dislocated (Figure 2A). 4
Removal of the fractured PMMA cranioplasty was indicated, and during the same operation a PEEK PSI was inserted (Figure 2B and 2C). The shards of the fractured implant were sealed in separate plastic bags, and stored at 4 °C in the dark. The PSI operation was complicated by a postoperative epidural hematoma which was surgically evacuated. After two months the patient visited the outpatient clinic and reported an improvement of his symptoms.
ABC
Figure 2: A) 3D reconstruction (left) of the fractured cranioplasty and the remaining dislocated shards. B) PEEK cranioplasty in situ. C) Fractured CMW-3 cranioplasty in situ.
Three analytical techniques, gel permeation chromatography (GPC), micro-computed tomography (μCT) and flexural strength, were used to determine whether the chemical, structural, and mechanical properties of CMW-3 had changed during 15 years in vivo. With the use of finite element analysis (FEA), the mechanical behavior of the fractured implant was analyzed to better understand the underlying reasons for failure.
In vivo fractured PMMA cranioplasty
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