Page 45 - Clinical relevance of current materials for cranial implants

Autologous bone is inferior to alloplastic cranioplasties
DISCUSSION
This systematic review shows that cranioplasties are associated with a high 2 complication rate, particularly when using autologous bone, mainly because of the
high infection and resorption rates and subsequent graft removal.
Resorption occurred most frequently in autologous bone, which is inherent to the tissue and may compromise the structural integrity. Resorption in allografts is limited to the interface between implant and surrounding bone and may therefore be less likely to occur. Other complication rates in autologous bone cranioplasties are more similar to, for example, HA, which is the main mineral constituent of bone. PEEK is custom made preoperatively, requires less surgical time, and has no burrs that require removal.
To date, 228 studies on the safety of cranioplasties are available, published during a 65- year span. However, a large variety exists in reported primary and secondary outcomes, and their definitions, as well as the protocols applied for cranioplasties, which makes meta-analysis futile. Meta-analyses in some reviews were conducted with heterogeneous studies70, whereas other reviews largely focused on a subjective analysis of the most commonly used materials10. Corliss et al.4 included 48 studies (n=5346 patients) and related the way of storage (abdominal pocket or cryopreservation) of autologous bone flaps for cranioplasties to survival rates. They found a total infection rate of 7.32% (n=2937) in the cryopreservation group versus 7.08% (n=527) in the abdominal pocket group. Resorption rate in 19 studies was 9.66% (n=1826) in the cryopreservation group and 7.69% (n=341) in the abdominal pocket group. Malcolm et al.5 reported similar infection rates, but the materials used for cranioplasty were not reported. Punchak et al.71 found an infection rate of 6% in a meta-analysis of 15 studies applying 183 PEEK cranioplasties. These reviews had a limited scope, disregarding putative confounders such as patient population, comorbidities, defect location and size, time between decompressive craniectomy and cranioplasty, material, antibiotics usage, frontal sinus involvement, or drain placement.
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