Microbiological profile and infection potential of different cryopreserved skull flaps after decompressive hemicraniectomy. Is cryopreservation at − 80 ℃ better?

OBJECTIVE: Patterns of cryopreservation of explanted skull bone flaps have long been a matter of debate, in particular the appropriate temperature of storage. To the best of our knowledge no study to date has compared the microbiological profile and the infection potential of skull bone flaps cryostored at the same institution at disparate degrees for neurosurgical purposes. In the context of our clinical trial DRKS00023283, we performed a bacterial culture of explanted skull bone flaps, which were cryopreserved lege artis at a temperature of either − 23 °C or − 80 °C after a decompressive hemicraniectomy. In a further step, we contaminated the bone fragments in a s uspension with specific pathogens (S. aureus, S. epidermidis and C. acnes, Colony forming unit CFU 10(3)/ml) over 24 h and conducted a second culture. RESULTS: A total of 17 cryopreserved skull flaps (8: − 23 °C; 9: − 80 °C) explanted during decompressive hemicraniectomies performed between 2019 and 2020 as well as 2 computer-aided-designed skulls (1 vancomycin-soaked) were analyzed. Median duration of cryopreservation was 10.5 months (2–17 months). No microorganisms were detected at the normal bacterial culture. After active contamination of our skull flaps, all samples showed similar bacterial growth of above-mentioned pathogens; thus, our study did not reveal an influence of the storage temperature upon infectious dynamic of the skulls.