Cryopreservation of autologous bone flaps following decompressive craniectomy: A new method reduced positive cultures without increase in post-cranioplasty infection rate

Abstract

Introduction: Cranioplasty (CP) after decompressive craniectomy (DC) is a common neurosurgical procedure. Implementation of European Union (EU) directives recommending bacterial cultures before cryopreservation, lead to increased number of autologous bone flaps being discarded due to positive cultures. A new method for handling bone flaps prior to cryopreservation, including the use of pulsed lavage, was developed.

Research question: The aim was to evaluate the effect of a new method on proportion of positive bacterial cultures and surgical site infection (SSI) following CP surgery.

Material and methods: Sixty-one bone flaps from 53 consecutive DC surgery patients were retrospectively included and the study period was divided into before and after method implementation. Patient demographics, laboratory and culture results, type of CP and occurrence of SSI were analyzed.

Results: Twenty-six and 18 bone flaps were available for analysis during the first and second period, respectively. The proportion of positive bacterial cultures was higher in the first period compared to the second (n ​= ​9(35%) vs 0(0%); p ​= ​0.001), and thus the use of custom made implants was considerably higher in the first study period (p ​= ​0.001). There was no difference in the frequency of post-cranioplasty SSI between the first and second study period (n ​= ​3 (11.5%) vs 1 (4.8%), p ​= ​0.408).

Discussion and conclusion: The new method for handling bone flaps resulted in a lower frequency of positive bacterial cultures, without increased frequency of post-cranioplasty SSI, thus demonstrating it is safe to use, allows compliance with the EU-directives, and may reduce unnecessary discarding of bone flaps.

Keywords: BFR, bone flap resorption; Bacterial culture; CP, cranioplasty; Cranioplasty; Cryopreservation; DC, decompressive craniectomy; Decompressive craniectomy; GCS-m, Glasgow coma scale motor score; ICP, intracranial pressure; Pulsed lavage; SAH, subarachnoid hemorrhage; SSI, surgical site infection; TBI, traumatic brain injury.

Fig. 1

Flow chart of included patients. Sixty-one bone flaps from 53 consecutive patients were included in the study in total, with 34 and 27 bone flaps in the first and second study period, respectively. In the first study period eight bone flaps were lost to follow-up in the first period due to death prior to cranioplasty (CP; n ​= ​3), no access to records of CP (n ​= ​3) or deliberate choice not to have CP surgery (n ​= ​2). In the second period five bone flaps were lost to follow-up due to patient death prior to cranioplasty (n ​= ​4), or patients deliberate choice not to have CP surgery (n ​= ​1). This resulted in 26 bone flaps included in the first study period and 21 bone flaps in the second study period.

Fig. 2

Illustration of the new method of bone flap handling A) A decompressive craniectomy is performed and the bone flap is removed from the patient. B) The bone flap is cleansed from any soft tissue and rinsed with saline solution. C) The bone flap is rinsed using pulsed lavage with saline solution. Plastic covers are arranged around a bowl in order to avoid the rinse water splashing back and re-contaminating the bone flap. D) A culture swab is taken from the surface of the bone flap and sent to the laboratory. The bone flap is packaged in surgical swabs, a sterile surgical glove, and a sterile bag. The bag is then tagged with identification data and delivered to the bone freezer for cryopreservation.