Safety of untreated autologous cranioplasty after extracorporeal storage at − 26 degree celsius

Autologous Cranioplasty with Bone Flap Preserved in Conventional Freezers: An Adequate Option in Low Resource Settings

BACKGROUND

Autologous cranioplasty has been used for decades and is the gold standard treatment in patients who underwent decompressive craniectomy (DC). One of the most common methods to store the cranial bone flap is cryopreservation at very low temperatures (-70 to -80°). The only way to achieve these low temperatures is by using special freezers which are not always available in all medical facilities, especially in low-resource centers. This paper describes our experience with the storage of cranial bone flaps in freezers of conventional refrigerators.

METHODS

This retrospective study included patients treated with autologous cranioplasty, operated between 2015 and 2020. The cranial bone flap was stored at -18°C in the freezer of conventional refrigerators. Complications and outcomes were analyzed and compared with reports of patients in whom ultra-low temperature freezers were used for bone flap preservation.

RESULTS

Twenty-five patients were included. The average follow-up period was 33 months. Trauma was the most common cause of DC, followed by stroke. The mean age was 36.7. Aseptic bone flap resorption was observed in 4 cases (16%). No cases of infection were observed.

CONCLUSIONS

The use of freezers from conventional refrigerators may be an acceptable alternative for the preservation of the cranial bone flap in facilities where special freezers are not available. The rate of aseptic bone necrosis and infections observed in this paper was similar to the incidence of these complications reported in studies where ultra-low temperatures were used.

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 103/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.

The storage of skull bone flaps for autologous cranioplasty: literature review

The use of autologous bone flap for cranioplasty after decompressive craniectomy is a widely used strategy that allows alleviating health expenses. When the patient has recovered from the primary insult, the cranioplasty restores protection and cosmesis, recovering fluid dynamics and improving neurological status. During this time, the bone flap must be stored, but there is a lack of standardization of tissue banking practices for this aim. In this work, we have reviewed the literature on tissue processing and storage practices. Most of the published articles are focused from a strictly clinical and surgical point of view, paying less attention to issues related to tissue manipulation. When bone resorption is avoided and the risk of infection is controlled, the autograft represents the most efficient choice, with the lowest risk of complication. Otherwise, depending on the degree of involvement, the patient may have to undergo new surgery, assuming further risks and higher healthcare costs. Therefore, tissue banks must implement protocols to provide products with the highest possible clinical effectiveness, without compromising safety. With a centralised management of tissue banking practices there may be a more uniform approach, thus facilitating the standardization of procedures and guidelines.

Establishment and Characteristic Analysis of a Dog Model for Autologous Homologous Cranioplasty

Objective

The aim of this study is to establish a large animal (dog) model that can be referred clinically for autologous homologous cranioplasty.

Methods

Our large skull defect dog model was established by emulating the decompressive craniectomy with 22 adult beagle dogs. The autologous bones were taken out from the dogs and divided into two groups, the freeze-drying (FD) group and the single freezing (SF) group. They were then stored in the bone bank at -20°C after being irradiated with 25 KGy. Three months later, the bones were reimplanted. After operation, we closely watch the experimental objects for four more months examining the infection and survival of the bone graft.

Results

Through macroscopic observation, it was found that, among 44 cranial flaps (bilateral) from the rest of the 22 dogs, grade A cranial flaps accounted for 86.4% (19/22) in the SF group and only 31.8% (7/22) in the FD group. Although osteogenic osteoclast, Harvard tube, neovascularization, and angiogenic factors were found through the pathological results, including an electron microscope and calmodulin tracer, it could be verified by using X-CT and micro-CT that early bone resorption could be still found even in grade A bone flap.

Conclusion

By using the common clinical method to preserve the cranial flaps, we established an experimental dog model of autologous cranioplasty for a large area of cranial defect. It was proved that this model could reproduce the infections and bone resorption which typically happened in clinical autologous homologous cranioplasty. As a conclusion, the established model can be used as an effective experimental tool for further research to improve the success rate of autologous homologous cranioplasty.

Is Three-Dimensional Virtual Planning in Cranial Reconstruction for Advanced Cutaneous Squamous Cell Carcinoma of the Skull a Feasible Option?

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) is a common type of malignant skin disorder. An uncommon feature is local bony invasion, as can rarely be seen in lesions on the scalp. The optimal treatment strategy in these rare cases is still under debate.

OBJECTIVE

The aim of this case report is to present a 1-stage three-dimensional planned surgical resection and reconstruction of a cSCC with bony invasion into the scalp and to discuss the alternative options and potential pitfalls.

MATERIALS AND METHODS

A patient diagnosed with rT4N0M0 cSCC of the scalp underwent a cranial resection and reconstruction in 1 stage. With the use of computer-assisted design and computer-assisted manufacturing a patient-specific implant (PSI) of poly (ether ether ketone) was manufactured. After the PSI was inserted, it was covered with a latissimus dorsi muscle and a split-thickness skin graft.

RESULTS

Intraoperatively the resection template generated an accurate resection and accurate and fast placement of the PSI. The reconstruction had a clinical satisfactory esthetic result, but was hampered by the development of a small wound dehiscence was observed over the postoperative course.

CONCLUSION

Three-dimensional planned resection and reconstruction for composite defects of the skull after resection of a cSCC of the scalp with bony invasion may lead to an accurate and predictable resection and accurate and fast placement of the PSI. However, patient specific characteristics should be considered to assess potential risks and benefits before opting for this one-stage treatment strategy.

Factors related to failure of autologous cranial reconstructions after decompressive craniectomy

PURPOSE

Cranioplasty is customary after decompressive craniectomy. Many different materials have been developed and used for this procedure. The ideal material does not yet exist, while complication rates in cranioplasties remain high. This study aimed to determine factors related to autologous bone flap failure.

MATERIALS AND METHODS

In this two-center retrospective cohort study, 276 patients underwent autologous bone cranioplasty after initial decompressive craniectomy between 2004 and 2014. Medical records were reviewed regarding patient characteristics and factors potentially related to bone flap failure. Data were analyzed using univariable and multivariable regression analysis.

RESULTS

Independent factors related to overall bone flap failure were: duration of hospitalization after decompressive craniectomy [OR: 1.012 (95%CI: 1.003-1.022); p = 0.012], time interval between decompressive craniectomy and cranioplasty [OR: 1.018 (95%CI: 1.004-1.032); p = 0.013], and follow-up duration [OR: 1.034 (95%CI: 1.020-1.047); p < 0.001]. In patients with bone flap infection, neoplasm as initial diagnosis occurred significantly more often (29.2% vs. 7.8%; RD 21.3%; 95%CI 8.4 -38.3%; NNH 5; 95%CI 3 -12) and duration of hospitalization after decompressive craniectomy tended to be longer (means 54 vs. 28 days, MD 26.2 days, 95%CI -8.6 to 60.9 days). Patients with bone flap resorption were significantly younger (35 vs. 43 years, MD 7.7 years, 95%CI 0.8-14.6 years) and their cranial defect size tended to be wider than in patients without bone flap resorption (mean circumference 39 vs. 37 cm; MD 2.4 cm, 95% CI -0.43-5.2 cm) and follow-up duration was significantly longer (44 vs. 14 months, MD 29 months, 95%CI 17-42 months).

CONCLUSION

A neoplasm as initial diagnosis, longer hospitalization after decompressive craniectomy, larger time interval between decompressive craniectomy and cranioplasty, and longer follow-up duration are associated with a higher risk of failure of autologous bone flaps for cranioplasty. Patients with these risk factors may be better served with an early recovery program after decompressive surgery or an alloplastic material for cranioplasty.

Cryostored autologous skull bone for cranioplasty? A study on cranial bone flaps' viability and microbial contamination after deep-frozen storage at -80°C

Craniectomy is a life-saving procedure. Subsequent cranioplasty with autologous skull bone has a bone resorption rate from 4% to 22.8% and an infection rate from 3.3% to 26%. There are concerns with their viability and the potential microbial contamination as they were explanted for a long period of time. Eighteen cranial bone flaps stored at Prince of Wales Hospital Skull Bone Bank during the period from June 2011 to March 2016 were identified. Ethics approval was obtained. Bone chips and deep bone swabs were collected for osteoblast culture and microbial culture. Skull Bone Bank was kept at -80°C under strict aseptic technique during the study period. The storage period ranged from 4months to 55months. For the osteoblast culture, all eighteen bone flaps had no viable osteoblast growth. For the bacterial culture, five had positive bacteria growth (27.8%). Three were Pasteurella multocida and two were Methicillin-resistant Staphylococcus aureus. The mean duration of storage of the infected bone flap was 32.9months (±15.1months) versus 19.9months (±17.9months) of those bone flaps with no bacterial growth (p=0.1716). The mean size of the infected versus non-infected bone flaps was 117.7cm² (±44.96cm²) versus 76.8cm² (±50.24cm²) respectively (p=0.1318). Although in this study statistical significance was not reached, it was postulated that infected bone flaps tended to be larger in size and had a longer duration of storage. In conclusion, cryostored skull bone flaps beyond four months showed no viable osteoblasts. Bacterial contamination rate of bone flaps was 27.8% in this study.

Cranioplasty Outcomes and Analysis of the Factors Influencing Surgical Site Infection: A Retrospective Review of More than 10 Years of Institutional Experience

BACKGROUND

As a large amount of clinical evidence supports the use of craniectomy, the frequency of subsequent cranioplasty is increasing. Conflicting complication rates and risk factors of cranioplasty have been reported. We reviewed >10 years of institutional experience to identify risk factors of surgical site infection (SSI) after cranioplasty.

METHODS

A retrospective review was conducted of patients who underwent primary cranioplasty. Patients <16 years old, patients with a history of cranial infection, and patients who underwent ventricular shunt surgery were excluded. There were 155 patients eligible for analysis. Complication rate and the risk factors associated with SSI were determined.

RESULTS

The overall complication rate was 12.3%. There were 13 cases of SSI (8.4%), 4 cases of postoperative epidural hemorrhage (2.6%), and 2 cases of postoperative wound dehiscence (1.3%). There was a significant relationship between operative time and SSI (P < 0.001). The optimal cutoff value of operative time for predicting SSI was 98 minutes, and the relative risk ratio was 7.4 in patients with an operative time of >98 minutes.

CONCLUSIONS

A high number of complications can occur after cranioplasty. Close attention should be paid to SSI development in patients who require a long operative time.

Early cranioplasty vs. late cranioplasty for the treatment of cranial defect: A systematic review

BACKGROUND

Cranioplasty is considered as a routine procedure in everyday neurosurgical practice for the patient with cranial defect, however, there is no established consensus on optimal surgical timing.

OBJECTIVE

To compare the effect of early cranioplasty (1-3 months after DC) and late cranioplasty (3-6 months after DC) on the complications and recovery of neurological function in the management of patients who received decompressive craniotomy.

METHODS

In this paper, the authors report a systematic review and meta-analysis of operative time, complications and neurological function outcomes on different timing of cranioplasty. Randomized or non-randomized controlled trials of early cranioplasty and late cranioplasty surgery were considered for inclusion.

RESULTS

Nine published reports of eligible studies involving 1209 participants meet the inclusion criteria. Compared with late cranioplasty, early cranioplasty had no significant difference in overall complications [RR=1.14, 95%CI (0.83, 1.55), p>0.05], infection rates [RR=0.87, 95%CI (0.47, 1.61), p>0.05], intracranial hematoma [RR=1.09, 95%CI (0.53, 2.25), p>0.05]; subdural fluid collection [RR=0.47, 95%CI (0.15, 1.41), p>0.05]. However, early CP significantly reduced the duration of cranioplasty [mean difference=-13.46, 95%CI (-21.26, 5.67), p<0.05]. The postoperative hydrocephalus rates were significant higher in the early cranioplasty group [RR=2.67, 95%CI (1.24, 5.73), p<0.05].

CONCLUSION

Early CP can only reduce the duration of operation, but cannot reduce the complications of patients and even increase the risk of hydrocephalus. More evidence from advanced multi-center studies is needed to provide illumination for the timing selection of CP surgery.

Autologous cranioplasty following decompressive craniectomy in the trauma setting

BACKGROUND

Decompressive craniectomy (DC) is an option for the treatment of increased intracranial pressure resulting from an acute neurological insult, including insults caused by trauma. When the brain swelling has receded, the skull is reconstructed with a wide choice of materials, each with its own advantages and disadvantages in terms of cost, cosmetic appearance, biocompatibility, implant strength and complication rate. Autologous cranioplasty (AC), where the patient's own bone flap is stored and reutilised, is common in many countries. No outcome studies have, however, been published on this technique for traumatic injuries.

METHODS

A retrospective study was conducted including all AC operations performed following DC due to traumatic brain injury. All operations were performed in one institution during a 4-year time period. Results were analysed for complication rates.

RESULTS

44 cases were included. The mean time from craniotomy to cranioplasty was 86 (95% CI: 63-109) days. Complications severe enough to warrant readmission or further surgery were found in 13 cases (30%). No statistically significant predictor of complication from cranioplasty was detected. The complication rate was similar to published data on cranioplasty using artificial prosthetic materials.

CONCLUSIONS

AC in the trauma setting is a valid treatment option with a complication rate that seems no worse than other alternatives.