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.

Effect of microorganisms isolated by preoperative osseous sampling on surgical site infection after autologous cranioplasty: A single-center experience

PURPOSE

The most frequent postoperative complication in autologous cranioplasty (AC) is infection. European recommendations include osseous sampling before cryogenic storage of a bone flap. We evaluated the clinical impact of this sampling.

METHODS

All patients who underwent decompressive craniectomy (DC) and AC in our center between November 2010 and September 2021 were reviewed. The main outcome was the rate of reoperation for infection of the cranioplasty. We evaluated risk factors for bone flap infection, rate of reoperation for any reason (hematoma, skin erosion, cosmetic request, or bone resorption), and radiological evidence of bone flap resorption.

RESULTS

A total of 195 patients with a median age of 50 (interquartile range: 38.0-57.0) years underwent DC and AC between 2010 and 2021. Of the 195 bone flaps, 54 (27.7%) had a positive culture, including 48 (88.9%) with Cutibacterium acnes. Of the 14 patients who underwent reoperation for bone flap re-removal for infection, 5 and 9 had positive and negative bacteriological cultures, respectively. Of patients who did not have bone flap infection, 49 and 132 had positive and negative bacteriological cultures, respectively. There were no significant differences between patients with and without positive bacteriological culture of bone flaps in the rates of late bone necrosis and reoperation for bone flap infection.

CONCLUSIONS

A positive culture of intraoperative osseous sampling during DC is not associated with a higher risk of re-intervention after AC.

Post-traumatic hydrocephalus may be associated with autologous cranioplasty failure, independent of ventriculoperitoneal shunt placement: a retrospective analysis

PURPOSE

Decompressive craniectomy (DC) is a common procedure used for the treatment of intracranial hypertension. Once brain swelling has subsided, a cranioplasty is performed to restore cosmesis and protection to the brain. While using the patient's autologous bone flap is often the first choice in cranioplasty, this procedure is frequently complicated by bone flap resorption and infection. This study seeks to identify predictors of autologous cranioplasty failure.

METHODS

A retrospective analysis was conducted on patients who underwent decompressive craniectomy and autologous cranioplasty. Patient demographics and factors related to both surgeries and failure rates were recorded from patient records. Logistic regressions were conducted to determine which factors were implicated in autologous cranioplasty failure.

RESULTS

In our cohort, 127 patients underwent autologous cranioplasty. Overall, 18 (14.2%) patients experienced autologous cranioplasty failure. Regression analysis identified development of post-traumatic hydrocephalus (PTH) following DC (OR: 3.26, p = 0.043), presence of neurological deficits following DC (OR: 4.88, p = 0.025), and reoperation prior to CP (OR 3.0, p = 0.049) as significant predictors of autologous cranioplasty failure. Of the 16 patients who developed PTH following DC, 9 received a VP shunt. The rate of flap failure was similar across the 9 PTH patients who received a shunt and the 7 PTH patients who did not receive a shunt (33% vs. 57% failure rate, respectively, p = 0.341).

CONCLUSION

Autologous cranioplasty is a reasonably successful procedure with a flap failure rate of 14.2%. We identified PTH, persistent neurological deficits, and reoperation prior to cranioplasty as significant predictors of autologous cranioplasty failure. Interestingly, the presence of VP shunt did not impact the odds of flap failure.

Protocol for the multicentre prospective paediatric craniectomy and cranioplasty registry (pedCCR) under the auspices of the European Society for Paediatric Neurosurgery (ESPN)

PURPOSE

In the paediatric age group, the overall degree of evidence regarding decompressive craniectomy (DC) and cranioplasty is low, whereas in adults, randomised controlled trials and prospective multicentre registries are available. To improve the evidence-based treatment of children, a consensus was reached to establish a prospective registry under the auspices of the European Society for Pediatric Neurosurgery (ESPN).

METHODS

This international multicentre prospective registry is aimed at collecting information on the indication, timing, technique and outcome of DC and cranioplasty in children. The registry will enrol patients ≤ 16 years of age at the time of surgery, irrespective of the underlying medical condition. The study design comprises four obligatory entry points as a core dataset, with an unlimited number of further follow-up entry points to allow documentation until adolescence or adulthood. Study centres should commit to complete data entry and long-term follow-up.

RESULTS

Data collection will be performed via a web-based portal (homepage: www.pedccr.com ) in a central anonymised database after local ethics board approval. An ESPN steering committee will monitor the project's progress, coordinate analyses of data and presentation of results at conferences and in publications on behalf of the study group.

CONCLUSION

The registry aims to define predictors for optimal medical care and patient-centred treatment outcomes. The ultimate goal of the registry is to generate results that are so relevant to be directly transferred into clinical practice to enhance treatment protocols.

Long-term complications and implant survival rates after cranioplastic surgery: a single-center study of 392 patients

Cranioplasty (CP) is a standard procedure in neurosurgical practice for patients after (decompressive) craniectomy. However, CP surgery is not standardized, is carried out in different ways, and is associated with considerable complication rates. Here, we report our experiences with the use of different CP materials and analyze long-term complications and implant survival rates. We retrospectively studied patients who underwent CP surgery at our institution between 2004 and 2014. Binary logistic regression analysis was performed in order to identify risk factors for the development of complications. Kaplan-Meier analysis was used to estimate implant survival rates. A total of 392 patients (182 females, 210 males) with a mean age of 48 years were included. These patients underwent a total of 508 CP surgeries. The overall complication rate of primary CP was 33.2%, due to bone resorption/loosening (14.6%) and graft infection (7.9%) with a mean implant survival of 120 ± 5 months. Binary logistic regression analysis showed that young age (< 30 years) (p = 0.026, OR 3.150), the presence of multidrug-resistant bacteria (p = 0.045, OR 2.273), and cerebrospinal fluid (CSF) shunt (p = 0.001, OR 3.137) were risk factors for postoperative complications. The use of titanium miniplates for CP fixation was associated with reduced complication rates and bone flap osteolysis as well as longer implant survival rates. The present study highlights the risk profile of CP surgery. Young age (< 30 years) and shunt-dependent hydrocephalus are associated with postoperative complications especially due to bone flap autolysis. Furthermore, a rigid CP fixation seems to play a crucial role in reducing complication rates.

Autologous Calvarial Bone Remodeling Technique for Small to Medium-Sized Cranial Defects in Young Children: The "Switch-Cranioplasty" Technique

INTRODUCTION

Reconstruction of cranial defects in children less than 2 years of age, particularly when there is an associated dural defect, is challenging due to the need to accommodate active skull growth, limited options for autologous bone graft and thin calvarial bones. We use a simple remodeling technique that exploits the normal dura's inherent potential for new bone growth while covering the dural defect with adjacent skull.

CASE PRESENTATION

We describe an alternating, two-piece craniotomy or "switch-cranioplasty technique" to repair an occipital meningocele. The two pieces of craniotomy bone flap created around the existing skull and dural defect are switched in the horizontal plane in order to cover the site of the defect and the abnormal dura of the meningocele closure. The area of the original skull defect is transposed laterally over the normal dura. The healing of the lateral skull defects is facilitated with autologous bone chips and dust and covered by periosteal flaps that stimulate spontaneous re-ossification.

DISCUSSION

The advantages of this technique are the use of autologous bone adjacent to the skull defect, incorporation of the autologous bone into the growing skull, an acceptable cosmetic and functional outcome in a simple manner. The indications can be extended to include small to medium-sized calvarial defects secondary to leptomeningeal cyst and trauma.

A randomised controlled trial comparing autologous cranioplasty with custom-made titanium cranioplasty: long-term follow-up

OBJECTIVE

To compare the long-term outcomes of patients who had been randomly allocated to receive primary titanium cranioplasty or autologous bone graft following decompressive craniectomy.

METHODS

Sixty-four patients had been previously enrolled and randomised to receive either their own bone graft or a primary titanium cranioplasty. Functional and cosmetic outcomes had previously been assessed at 1-year following the cranioplasty procedure. Hospital records and the Picture Archiving communication system were reviewed to determine how many patients had cranioplasty failure or associated complications such as seizures beyond 1 year-with a minimum of 24-month follow-up.

RESULTS

Amongst the 31 patients in the titanium group (one patient had died), no patients had a partial or complete cranioplasty failure at 12 months follow-up and there had been no failures beyond 12 months. Amongst the 31 patients who had an autologous cranioplasty (one patient had died), 7 patients had complete resorption of the autologous bone such that it was adjudged a complete failure at 12-month follow-up. Five of these patients had had titanium augmentation and two patients declined further surgery. Both of these patients requested cranial augmentation for functional and cosmetic reasons subsequent to the 12-month follow-up. Another patient who had previously been noted to have moderate resorption at 12 months presented 1 year later with progressive bone flap resorption and also required subsequent augmentation for functional and cosmetic reasons. When follow-up was extended to a minimum of 24 months, use of titanium instead of autologous bone for primary cranioplasty resulted in a significant reduction in the number of patients who required rescue cranioplasty (0 vs 25%, 95% confidence interval [CI] 9.1-42.1%; p = 0.001). In addition, there were significantly less total hospital healthcare costs in those patients randomised to the titanium arm of the trial (difference = A$9999, 95%CI 2231-17,768; p = 0.015).

CONCLUSIONS

Bone resorption continued to occur beyond 12 months after autologous cranioplasty; use of primary titanium cranioplasty after decompressive craniectomy reduced the number of reoperations needed and the associated long-term total hospital costs.

Cranioplasty

Cranioplasty following craniectomy for trauma is a common, safe neurosurgical procedure that restores the natural cosmesis and protective barrier of the skull and may be instrumental in normalizing cerebrospinal fluid dynamics after decompressive surgery. Understanding the factors influencing patient selection and timing of cranioplasty, the available materials and methods of skull reconstruction, and the technical nuances is critical for a successful outcome. Neurosurgeons must be prepared to manage the complications specific to this operation. This article reviews the indications, preoperative assessment and timing, most commonly used materials, operative technique, postoperative care, and complication management for cranioplasty.

Bone formation in subcutaneous pocket after bone flap preservation

Residual periosteum developed periosteal bone formation in the pocket 10 years after cranioplasty, lumpectomy was conducted on the left lower abdomen under local anesthesia. Pathological sections revealed abundant osteocytes and mature bone matrix, and confirmed the bone formation on the residual periosteum.

Fenestration of bone flap during interval autologous cranioplasty

Background:

Symptomatic extra-axial fluid may complicate cranioplasty and require urgent evacuation. Fenestration (F) of the bone flap may encourage extra-axial fluid absorption; however, literature has not explored this technique.

Methods:

Thirty-two consecutive patients who underwent interval autologous cranioplasty were divided into two groups: Fenestration, n = 24, and no fenestration (NF), n = 8. Fenestration involves placement of twist-drill holes 1–2 cm apart throughout the bone flap. Clinical data (age, sex, underlying pathology for cranioplasty, history of antiplatelet/anticoagulation [A/A], presence of drains, and length of Intensive Care Unit [ICU] stay) were collected. Postoperative volume and midline shift (MLS) were measured. Univariate analysis was performed for continuous variables; Fisher's exact test was performed for categorical variables.

Results:

For postoperative volume, NF group exhibited 33.745 ± 48.701 cm³; F group exhibited 20.832 ± 26.103 cm³ (P = 0.351). For MLS, NF group exhibited 3.055 ± 0.472 mm; F group exhibited 0.75 ± 0.677 mm (P = 0.009). MLS for the NF group subset with drains was 1.235 ± 0.566 mm, (P = 0.587 when compared to F group). For ICU length of stay, NF group exhibited 1.958 ± 1.732 days; F group exhibited 2.290 ± 0.835 days (P = 0.720). In NF group, for patients with no A/A, no drain exhibited MLS 4.00 ± 0.677 mm while a drain exhibited 1.845 ± 0.605 mm (P = 0.025); with A/A, no drain exhibited 5.75 ± 1.353 mm while a drain exhibited 0.625 ± 0.957 (P = 0.005). Four NF patients required reoperation compared to zero F patients (P = 0.550).

Conclusion:

Presumably, fenestrations augment surface area for extra-axial fluid absorption through the bone flap. Our results, regarding MLS and postoperative volume, provide support for this concept. Accordingly, bone flap fenestration has the potential to reduce extra-axial fluid accumulation.

Cryopreservation versus subcutaneous preservation of autologous bone flaps for cranioplasty: comparison of the surgical site infection and bone resorption rates

OBJECTIVE

Decompressive craniectomy is performed to treat malignant brain hypertension. Surgical site infection (SSI) and bone resorption are common complications following cranioplasty, and the storage method that minimizes such complication has yet to be identified.

METHODS

Over a 10-year period, the details of 290 decompressive craniectomy procedures performed at our trauma and stroke center were recorded. Bone flaps from 110 patients were preserved in subcutaneous pockets (SPs), and 180 were preserved via cryopreservation (CP).

RESULTS

SSIs occurred in 20 cases (18.2%) in the SP group and 20 cases (11.1%) in the CP group (P=0.129). After dividing each group according to the traumatic brain injury (TBI) etiologies, we found that in the SP group, the SSI rates in the TBI and non-TBI patients were 17.3% and. 20.7% (P=0.899), respectively, and in the TBI- and non-TBI CP-group patients, the SSI rates were 11.9% and. 9.7% (P=0.864), respectively. The average decrease in bone flap thicknesses were 1.14 mm in the SP group (n=34) and 1.89 mm in the CP group (n=57), and this difference was significant (P=0.039).

CONCLUSIONS

In this series, the SSI rates were similar in the SP and CP groups. There was no significant difference when the patients were grouped by TBI etiology. The incidence of bone flap resorption in the CP group was higher than that in the SP group. However, identifying of the method that yields superior results might depend on the individual surgeon's preference and the available equipment.