Autologous bone flap versus hydroxyapatite prosthesis in first intention in secondary cranioplasty after decompressive craniectomy: a French medico-economical study

Cryopreserved bone flaps from decompressive craniectomies: a microbiological analysis

PURPOSE

Surgical site infection (SSI) is a serious complication after cranioplasty. Due to the relatively frequent occurrence of post-cranioplasty SSI, the utility of autologous bone flap swab cultures surrounding cryopreservation as a reliable predictor has been the subject of an ongoing debate. This bicentric study aims to contribute to this topic by conducting an in-depth analysis of bone flaps obtained via decompressive craniectomies. This study had three major aims: assessments of 1) bacterial contamination of bone flaps after decompressive craniotomy, 2) impact of cryoconservation on contamination rates and 3) potential effectiveness of anti-infective treatment to reduce the germ load prior to cranioplasty.

METHODS

Cryopreserved bone flaps from two centers were used. Microbiological cultivations of swabs prior to and after cryopreservation were taken and assessed for aerobic and anaerobic growth over a 14-day incubation period. Additionally, in a subset of bone flaps, swab testing was repeated after thorough rinsing with an anti-infectant (octenidine-phenoxyethanol) followed by saline.

RESULTS

All 63 bone flaps (patients median age at surgery: 59 years) were obtained via decompressive craniectomies. Swabs done prior to cryopreservation revealed a 54% infection rate with Propionibacterium acnes being the most common microorganism in 65% of those cases. After thorough disinfection of the preserved bone flaps, all but one case showed no bacterial growth in swab testing. Furthermore, no relevant risk factors for bacterial contamination could be identified.

CONCLUSION

This retrospective study showed the common presence of bacterial growth in cryopreserved bone flaps before and after freezing. Rinsing with octenidine-phenoxyethanol and saline effectively prevented bacterial growth in a notable percentage of cases, suggesting a potential strategy to reduce contamination. However, persistent bacterial growth in some cases underscores the need for further research to optimize antiseptic measures during autologous cranioplasty.

Infection-related failure of autologous versus allogenic cranioplasty after decompressive hemicraniectomy - A systematic review and meta-analysis

Introduction

Cranioplasty is required after decompressive craniectomy (DC) to restore brain protection and cosmetic appearance, as well as to optimize rehabilitation potential from underlying disease. Although the procedure is straightforward, complications either caused by bone flap resorption (BFR) or graft infection (GI), contribute to relevant comorbidity and increasing health care cost. Synthetic calvarial implants (allogenic cranioplasty) are not susceptible to resorption and cumulative failure rates (BFR and GI) tend therefore to be lower in comparison with autologous bone. The aim of this review and meta-analysis is to pool existing evidence of infection-related cranioplasty failure in autologous versus allogenic cranioplasty, when bone resorption is removed from the equation.

Materials and methods

A systematic literature search in PubMed, EMBASE, and ISI Web of Science medical databases was performed on three time points (2018, 2020 and 2022). All clinical studies published between January 2010 and December 2022, in which autologous and allogenic cranioplasty was performed after DC, were considered for inclusion. Studies including non-DC cranioplasty and cranioplasty in children were excluded. The cranioplasty failure rate based on GI in both autologous and allogenic groups was noted. Data were extracted by means of standardized tables and all included studies were subjected to a risk of bias (RoB) assessment using the Newcastle-Ottawa assessment tool.

Results

A total of 411 articles were identified and screened. After duplicate removal, 106 full-texts were analyzed. Eventually, 14 studies fulfilled the defined inclusion criteria including one randomized controlled trial, one prospective and 12 retrospective cohort studies. All but one study were rated as of poor quality based on the RoB analysis, mainly due to lacking disclosure why which material (autologous vs. allogenic) was chosen and how GI was defined. The infection-related cranioplasty failure rate was 6.9% (125/1808) for autologous and 8.3% (63/761) for allogenic implants resulting in an OR 0.81, 95% CI 0.58 to 1.13 (Z ​= ​1.24; p ​= ​0.22).

Conclusion

In respect to infection-related cranioplasty failure, autologous cranioplasty after decompressive craniectomy does not underperform compared to synthetic implants. This result must be interpreted in light of limitations of existing studies. Risk of graft infection does not seem a valid argument to prefer one implant material over the other. Offering an economically superior, biocompatible and perfect fitting cranioplasty implant, autologous cranioplasty can still have a role as the first option in patients with low risk of developing osteolysis or for whom BFR might not be of major concern.

Trial registration

This systematic review was registered in the international prospective register of systematic reviews. PROSPERO: CRD42018081720.

Ultra-High-Molecular-Weight Polyethylene Merlon Shape: Novel Fixation of Artificial Bone for Cranioplasty

BACKGROUND

Cranioplasty is a surgical procedure widely performed for repairing cranial defects caused by external decompression surgery for cerebrovascular disease or traumatic brain injury. We devised a new cranioplasty method using artificial bone made up of ultra-high molecular-weight polyethylene, with serrated wings on the edge. We named this newly designed artificial bone as Merlon shape.

OBJECTIVE

To describe our initial experience with the Merlon shape and evaluate its usefulness and safety in cranioplasty.

METHODS

The serrated wings of the Merlon shape were preoperatively designed for solid fixation and improving cosmetic results by reducing the thickness of the artificial bone. We evaluated 25 patients who underwent cranioplasty with the Merlon shape between December 2018 and December 2021. The causes of bone defects in these patients (male: 9, female: 16; median age: 62 years) were subarachnoid hemorrhage (n = 14), cerebral infarction (n = 8), and traumatic brain injury (n = 3).

RESULTS

There were no postoperative adverse events such as infection, bone resorption, implant exposure, or graft sinking in 24 patients during an average follow-up period of 19 months. One patient experienced acute epidural hemorrhage and required reoperation.

CONCLUSION

This is the first report on the use of the ultra-high molecular-weight polyethylene Merlon shape. Our initial 4-year case series showed good outcomes with this method.

Materials Used in Cranial Reconstruction: A Systematic Review and Meta-Analysis

BACKGROUND

Cranioplasty is a common neurological procedure with complication rates ranging from 20% to 50%. It is hypothesized that the risks of various complications are impacted by which material is used for cranioplasty.

OBJECTIVE

To evaluate existing literature comparing rates of complications following cranioplasty using different materials including autologous bone, hydroxyapatite, methyl methacrylate (MMA), demineralized bone matrix, polyetheretherketone, titanium, or composite materials.

METHODS

PubMed/MEDLINE database was searched for relevant articles published between 2010 and 2020. After screening, 35 articles were included. Outcomes included infection, wound problems, poor cosmesis, overall complications, duration of surgery, and length of stay. For each outcome, a frequentist network meta-analysis was conducted to compare materials used.

RESULTS

The risk of infection was 1.62 times higher when MMA was used compared to autologous bone (RR 1.62, 95% CI 1.07 to 2.45). Length of stay following cranioplasty was on average 3.62 days shorter when titanium was used compared autologous bone (95% CI -6.26 to -0.98). The networks constructed for other outcomes demonstrated moderate to substantial between-study heterogeneity, wide confidence intervals, and no significant differences between materials.

CONCLUSIONS

The quality of existing literature on this topic is relatively poor, almost exclusively comprised of single-center retrospective studies. There is currently not strong enough evidence available to make comprehensive conclusions regarding the risk-profiles of various cranioplasty materials across multiple outcomes. Prospective randomized trials are necessary to confirm the significant results found in this analysis and to further elucidate the differential risks of various cranioplasty materials.

The Materials Utilized in Cranial Reconstruction: Past, Current, and Future

BACKGROUND

Cranioplasty (CP) is associated with high complication rates compared to other common neurosurgical procedures. Several graft materials are used for CP, which may contribute to the high complication rates, but data in the literature regarding the influence of graft material on post-CP outcomes are inconsistent making it difficult to determine if, when, and to what extent the graft material impacts the rate of perioperative complications. There is an increased demand to identify and develop superior graft materials.

OBJECTIVE

To review and compare the indications, risks, complications, and patient results associated with the use of different graft materials for cranial reconstructions.

DESIGN

A search through EBSCOhost was conducted using the keywords "craniectomy" or "decompressive craniectomy," "cranioplasty," and "materials." The search was limited to literature published in the English language from 2005 until the present. Ultimately, 69 articles were included in this review. Due to the heterogeneity of the study populations, results, statistical analyses, and collecting methods, no statistical analyses could be performed.

CONCLUSIONS

Several graft materials have been adapted for use in cranial reconstructions with inconsistent results making it unclear if or when one material may be indicated over others. Advances in computer-aided design have led to improved patient-specific implants, but the ideal graft material is still being sought after in ongoing research efforts. Reviewing materials currently available, as well as those in clinical trials, is important to identify the limitations associated with different implants and to guide future research.

Security and reliability of CUSTOMBONE cranioplasties: A prospective multicentric study

BACKGROUND

Repairing bone defects generated by craniectomy is a major therapeutic challenge in terms of bone consolidation as well as functional and cognitive recovery. Furthermore, these surgical procedures are often grafted with complications such as infections, breaches, displacements and rejections leading to failure and thus explantation of the prosthesis.

OBJECTIVE

To evaluate cumulative explantation and infection rates following the implantation of a tailored cranioplasty CUSTOMBONE prosthesis made of porous hydroxyapatite. One hundred and ten consecutive patients requiring cranial reconstruction for a bone defect were prospectively included in a multicenter study constituted of 21 centres between December 2012 and July 2014. Follow-up lasted 2 years.

RESULTS

Mean age of patients included in the study was 42±15 years old (y.o), composed mainly by men (57.27%). Explantations of the CUSTOMBONE prosthesis were performed in 13/110 (11.8%) patients, significantly due to infections: 9/13 (69.2%) (p<0.0001), with 2 (15.4%) implant fracture, 1 (7.7%) skin defect and 1 (7.7%) following the mobilization of the implant. Cumulative explantation rates were successively 4.6% (SD 2.0), 7.4% (SD 2.5), 9.4% (SD 2.8) and 11.8% (SD 2.9%) at 2, 6, 12 and 24 months. Infections were identified in 16/110 (14.5%): 8/16 (50%) superficial and 8/16 (50%) deep. None of the following elements, whether demographic characteristics, indications, size, location of the implant, redo surgery, co-morbidities or medical history, were statistically identified as risk factors for prosthesis explantation or infection.

CONCLUSION

Our study provides relevant clinical evidence on the performance and safety of CUSTOMBONE prosthesis in cranial procedures. Complications that are difficulty incompressible mainly occur during the first 6 months, but can appear at a later stage (>1 year). Thus assiduous, regular and long-term surveillances are necessary.

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.

3D-Printer-Assisted Patient-Specific Polymethyl Methacrylate Cranioplasty: A Case Series of 16 Consecutive Patients

BACKGROUND

To develop a novel 3D-printer-assisted method to fabricate patient-specific implants for cranioplasty and to demonstrate its feasibility and its use in 16 consecutive cases.

METHODS

We report on 16 consecutive patients who have undergone cranioplasty surgery for an extensive skull defect after decompressive surgery and in which the bone flap was not available. We present the workflow for the implant production using a 3D-printer-assisted molding technique. Preoperative, intraoperative, and postoperative data were analyzed/evaluated.

RESULTS

Eleven out of our 16 patients (68.7%) presented with extensive hemispheric bone defects. Indication for initial craniotomy were traumatic brain injury (4; 25%), acute subdural hematoma (4; 25%), ischemic stroke (3; 18.8%), tumor (3; 18.8%), and ruptured aneurysm (2; 12.5%). Median (range) operation time was 121 (89-206) minutes. Median (range) intraoperative blood loss was 300 (100-3300) mL. The mean (range) follow-up period is 6 (0-21) months. Complications occurred in 7 out of our 16 patients (43.8%), in 6 (37.5%) of which a reoperation was required to evacuate an extra-axial hematoma (3; 50%), for shunting of an epidural fluid collection (1; 16.7%), or for skin flap necrosis (1; 16.7%). One patient (16.7%) developed a chronic asymptomatic subdural fluid collection that was stable over the follow-up period.

CONCLUSIONS

Our workflow to intraoperatively produce patient-specific implants in a timely manner to cover cranial defects proved to be feasible. The results are cosmetically appealing, and postoperative CT scans show well-fitting implants. As implantable printable substrates are already available, we aim to advance and certify 3D-printed patient-specific implants in the near future.

Patient-Specific Three-Dimensional Printing Guide for Single-Stage Skull Bone Tumor Surgery: Novel Software Workflow with Manufacturing of Prefabricated Jigs for Bone Resection and Reconstruction

OBJECTIVE

To describe a novel system workflow to design and manufacture patient-specific three-dimensional (3D) printing jigs for single-stage skull bone tumor excision and reconstruction and to present surgical outcomes of 14 patients.

METHODS

A specific computer-aided design/computer-aided manufacturing software and hardware system was set up, including a virtual surgical planning subsystem and a 3D printing-associated manufacturing subsystem. Computed tomography data of the patient's skull were used for 3D rendering of the skull and tumor. The output of patient-specific designing included a 3D printing guide for tumor resection and a 3D printing model of the bone defect after tumor excision. A polymethyl methacrylate implant was fabricated preoperatively and used for repair.

RESULTS

The specific 3D printing guide was used to design intraoperative jigs and implants for 14 patients (age range, 1-72 years) with skull bone tumors. In all cases, the cutting jig allowed precise excision of tumor and bone, and implants were exact fits for the defects created. All operative results were successful, without intraoperative or postoperative complications. Postoperative computed tomography scans were obtained for analysis. Postoperative 3D measurement of the skull symmetry index (cranial vault asymmetry index) showed significant improvement of head contour after surgery.

CONCLUSIONS

The computer-aided design/computer-aided manufacturing system described allows definitive preoperative planning and fabrication for treatment of skull bone tumors. Apparent benefits of the method include more accurate determination of surgical margins and better oncological outcomes.

Retrospective Chronologic Computed Tomography Analysis of Bone Flap Fusion and Resorption After Craniotomy and Autologous Cryopreserved Cranioplasty

BACKGROUND

In open brain surgery, fixation of the bone flap is the final procedure. The bone flaps then fuse naturally. The objective of this study was to investigate the chronological process of bone fusion after craniotomy and autologous cranioplasty.

METHODS

Retrospective data were collected from patients who underwent craniotomy or cranioplasty after August 2004 and had at least 1 computed tomography (CT) scan at 3 months postsurgery. The patients were divided into a craniotomy group and a cranioplasty group. Head CT scans were analyzed to evaluate bone fusion and resorption.

RESULTS

Records from 978 patients who underwent craniotomy or cranioplasty between September 2004 and November 2015 were reviewed; 369 patients were eligible for the final analysis (craniotomy, n = 276; cranioplasty, n = 93). The mean cryopreservation period for the bone flap in the cranioplasty group was 49.3 days. The mean patient age was 51.4 ± 18.1 years in the craniotomy group and 51.6 ± 17.1 years in the cranioplasty group. Head CT scans showed bone fusion rates of 76.6% in the craniotomy group and 53.3% in the cranioplasty group at 6 months postsurgery (P = 0.015) and 78.6% and 78.1%, respectively, at 1 year postsurgery (P = 0.951). There was also a significant difference in the bone flap resorption rate between the 2 groups.

CONCLUSIONS

Bone flap fusion rates after craniotomy and cranioplasty were significantly different before 12 months, but not significantly different thereafter. Bone resorption occurred more frequently in the cranioplasty group over time.

Long-Term Follow-Up Comparative Study of Hydroxyapatite and Autologous Cranioplasties: Complications, Cosmetic Results, Osseointegration

OBJECTIVE

A three-dimensional reconstruction technique using the CustomBone (CB) prosthesis allows custom-made cranioplasty (CP) possessing osseointegration properties owing to its porous hydroxyapatite (HA) composition. This reconstruction technique has replaced less expensive techniques such as subcutaneously preserved autologous bone (SP). Our primary objective was to evaluate complications between CB and SP CP techniques. A secondary objective was to assess cosmetic results and osseointegration of CPs.

METHODS

This single-center study comprised patients undergoing delayed CB or SP CP after craniectomy between 2007 and 2014. A prospective interview was conducted to collect all data, including 2-year follow-up clinical and radiologic data. Cosmetic results were assessed by a qualitative score, and osseointegration was assessed by measuring relative fusion at the CP margins.

RESULTS

Of 100 patients undergoing CB or SP CP between 2007 and 2014, 92 (CB, n = 44; SP, n = 48) participated in the prospective interview. No significant difference in complication rates was observed between the 2 groups. The main complication specific to the CB group was fracture of the prosthesis observed in 20.8% patients. A higher rate of good cosmetic results was observed in the CB group (92.5% vs. 74.3%, P = 0.031). In the CB group, 51% of patients demonstrated no signs of bone fusion of the CP.

CONCLUSIONS

Although the CB prosthesis is associated with cosmetic advantages, the porous hydroxyapatite composition makes it fragile in the short-term and long-term, and effective osseointegration remains uncertain.

Problems of reconstructive cranioplasty after traumatic brain injury in children

Cranial repair after traumatic brain injury in children is still burdened by unsolved problems and controversial issues, mainly due to the high rate of resorption of autologous bone as well as the absence of valid alternative material to replace the autologous bone. Indeed, inert biomaterials are associated to satisfactory results in the short period but bear the continuous risk of complications related to the lack of osteointegration capacity. Biomimetic materials claiming osteoconductive properties that could balance their mechanical limits seem to allow good cranial bone reconstruction. However, these results should be confirmed in the long term and in larger series. Further complicating factors that may affect cranial reconstruction after head injury should be identified in the possible associated alterations of CSF dynamics and in difficulties to manage the traumatic skin lesion and the surgical wound, which also might impact on the cranioplasty outcome. All the abovementioned considerations should be taken into account when dealing with the cranial reconstruction after decompressive craniectomy in children.

Osteoblast and Bacterial Culture from Cryopreserved Skull Flap after Craniectomy: Laboratory Study

Objective

Cranioplasty using a cryopreserved skull flap is a wide spread practice. The most well-known complications of cranioplasty are postoperative surgical infections and bone flap resorption. In order to find biological evidence of cryopreserved cranioplasty, we investigated microorganism contamination of cryopreserved skulls and cultured osteoblasts from cryopreserved skulls.

Methods

Cryopreserved skull flaps of expired patients stored in a bone bank were used. Cryopreserved skulls were packaged in a plastic bag and wrapped with cotton cloth twice. After being crushed by a hammer, cancellous bone between the inner and outer table was obtained. The cancellous bone chips were thawed in a water bath of 30°C rapidly. After this, osteoblast culture and general microorganism culture were executed. Osteoblast cultures were done for 3 weeks. Microorganism cultures were done for 72 hours.

Results

A total of 47 cryopreserved skull flaps obtained from craniectomy was enrolled. Of the sample, 11 people were women, and the average age of patients was 55.8 years. Twenty four people had traumatic brain injuries, and 23 people had vascular diseases. Among the patients with traumatic brain injuries, two had fracture compound comminuted depressed. The duration of cryopreservation was, on average, 83.2 months (9 to 161 months). No cultured osteoblast was observed. No microorganisms were cultured.

Conclusion

In this study, neither microorganisms nor osteoblasts were cultured. The biological validity of cryopreserved skulls cranioplasty was considered low. However, the usage of cryopreserved skulls for cranioplasty is worthy of further investigation in the aspect of cost-effectiveness and risk-benefit of post-cranioplasty infection.

Review of Cranioplasty after Decompressive Craniectomy

Cranioplasty is an in evitable operation conducted after decompressive craniectomy (DC). The primary goals of cranioplasty after DC are to protect the brain, achieve a natural appearance and prevent sinking skin flap syndrome (or syndrome of the trephined). Furthermore, restoring patients' functional outcome and supplementing external defects helps patients improve their self-esteem. Although early cranioplasty is preferred in recent year, optimal timing for cranioplasty remains a controversial topic. Autologous bone flaps are the most ideal substitute for cranioplasty. Complications associated with cranioplasty are also variable, however, post-surgical infection is most common. Many new materials and techniques for cranioplasty are introduced. Cost-benefit analysis of these new materials and techniques can result in different outcomes from different healthcare systems.

Hydroxyapatite ceramic implants for cranioplasty in children: a single-center experience

PURPOSE

The use of hydroxyapatite ceramic (HAC) implants for the treatment of skull defects in pediatric patients started 2010 at our institution. Ceramic implants facilitate osteoblast migration and therefore optimize osteointegration with the host bone. The purpose of this study is to report a single-center experience with this treatment modality.

METHODS

A retrospective review of all patients from July 2010 through June 2014 undergoing a cranioplasty using hydroxyapatite ceramic implant and managed at a single institution was performed. Indication for cranioplasty, the hospital course, and follow-up were reviewed. Bone density was measured in Hounsfield Units (HU) and osteointegration was calculated using Mimics Software® (Mimics Innovation Suite v17.0 Medical, Materialize, Leuven, Belgium).

RESULTS

Over the 4-year period, six patients met criteria for the study. Five patients had an osteointegration of nearly 100%. One patient had an incomplete osteointegration with a total bone-implant contact area of 69%. The mean bone density was 2800 HU (2300-3000 HU). Bone density alone is estimated to have a Hounsfield value between 400 and 2000 HU depending on the body region and bone quality. There were no major complications, and the patients were highly satisfied with the esthetical result.

CONCLUSION

Hydroxyapatite ceramic implants for cranioplasty in pediatric patients are a good choice for different indications. The implants show excellent osteointegration and esthetical results.

Septic complication following porous hydroxyapatite cranioplasty: prosthesis retention management

After failing of autologous cranioplasty or when the bone flap is unavailable, the alloplastic (heterologous) materials are the choice for cranial reconstruction. No agreement has been reported about the material with a significant lower risk of septic complications. This is due to extremely heterogeneous prognostic factors related not only to the material used but also to the surgical procedures and/or to the timing of the procedure. More attention should be focused on the material whose characteristic could enable a delay in bacterial colonization, where an antibiotic therapy could be effective, without need of prosthesis removal. Four cases of severe septic complication following cranioplasty with porous hydroxyapatite (HA) prosthesis are presented. Patients were conservatively treated, without heterologous bone flap removal. All of our patients presented reasons for delaying HA cranioplasty removal: patients #1, 3, and 4 had an associated shunted hydrocephalus and the need for not removing the prosthesis was related to the predictable recurrence of overshunting and/or sinking skin flap syndrome. In patient #4, the revision surgery would have also damaged the microvascular flap with latissimus dorsi muscle used by plastic surgeon for skin reconstruction. In patient #2, the patient refused revision surgery. In all cases, systemic and/or radiological signs of infection were observed. In patient #2 the infective process surrounded completely the HA prosthesis, while it was located in the epidural region in patients #1 and 4. In patient #3, a surgical curettage of the infected wound was performed over the HA prosthesis. Following prosthesis retention management with antibiotic therapy, all patients revealed systemic and/or radiological signs of sepsis resolution at follow-up. The possibility to avoid a prosthesis removal with effective antibiotic treatment is mainly due to the combination of three factors: targeted antibiotic therapy, good anatomical area revascularization (resulting of an "in situ" intake of antibiotics), and the biomimetism of HA prosthesis. Further investigations in a larger number of cases need to confirm these observations.

The feasibility of producing patient-specific acrylic cranioplasty implants with a low-cost 3D printer

OBJECT Commercially available, preformed patient-specific cranioplasty implants are anatomically accurate but costly. Acrylic bone cement is a commonly used alternative. However, the manual shaping of the bone cement is difficult and may not lead to a satisfactory implant in some cases. The object of this study was to determine the feasibility of fabricating molds using a commercial low-cost 3D printer for the purpose of producing patient-specific acrylic cranioplasty implants. METHODS Using data from a high-resolution brain CT scan of a patient with a calvarial defect posthemicraniectomy, a skull phantom and a mold were generated with computer software and fabricated with the 3D printer using the fused deposition modeling method. The mold was used as a template to shape the acrylic implant, which was formed via a polymerization reaction. The resulting implant was fitted to the skull phantom and the cranial index of symmetry was determined. RESULTS The skull phantom and mold were successfully fabricated with the 3D printer. The application of acrylic bone cement to the mold was simple and straightforward. The resulting implant did not require further adjustment or drilling prior to being fitted to the skull phantom. The cranial index of symmetry was 96.2% (the cranial index of symmetry is 100% for a perfectly symmetrical skull). CONCLUSIONS This study showed that it is feasible to produce patient-specific acrylic cranioplasty implants with a low-cost 3D printer. Further studies are required to determine applicability in the clinical setting. This promising technique has the potential to bring personalized medicine to more patients around the world.

Evolution of cranioplasty techniques in neurosurgery: historical review, pediatric considerations, and current trends

Cranial bone repair is one of the oldest neurosurgical practices. Reconstructing the natural contours of the skull has challenged the ingenuity of surgeons from antiquity to the present day. Given the continuous improvement of neurosurgical and emergency care over the past century, more patients survive such head injuries, thus necessitating more than ever before a simple, safe, and durable means of correcting skull defects. In response, numerous techniques and materials have been devised as the art of cranioplasty has progressed. Although the goals of cranioplasty remain the same, the evolution of techniques and diversity of materials used serves as testimony to the complexity of this task. This paper highlights the evolution of these materials and techniques, with a particular focus on the implications for managing pediatric calvarial repair and emerging trends within the field.

Post-marketing surveillance of CustomBone Service implanted in children under 7 years old

BACKGROUND

The CustomBone Service is a bioceramic implant suitable for cranial repair in both adults and children, although there are no clinical data about its use in children under 7 years of age. This surveillance study investigates the outcome in this age group.

METHOD

Twenty-eight children under 7 years old (range, 2.5-6 years) received CustomBone Service from July 2006 to May 2013 in 16 international hospitals. Data of 23 children (12 males and 11 females), harboring 24 prosthesis, were available with a minimum follow-up of 1 year.

FINDINGS

Sites of the cranial defect were frontal or parietal (20.8 % each), parieto-temporal (16.7 %), fronto-parietal or occipital (12.5 % each), fronto-parieto-temporal or fronto-temporal (8.3 % each). Initial diseases were trauma (54.2 %), malformation (37.5 %), or tumor of the bone/skin (8.3 %). Rupture of the implant occurred in a single case during the implant (1/26 surgeries, 3.8 %) and the cranial repair was achieved by means of the back-up prosthesis. Five adverse events were registered during the follow-up period consisting of three cases of fracture and two of exposure/infection of the prosthesis. All cases required the removal of the device (20.8 %).

CONCLUSIONS

The failure rate of CustomBone Service under 7 years of age was higher than reported in adults and children over 7 years old (20.8 vs. 3.8 %), However, CustomBone Service may be considered a valid option under 7 years old since other materials are burdened by more significant rates of complications in the long-term period. Due to specific properties of this material, indication to CustomBone Service in toddlers should be carefully evaluated by the surgeon on a case-by-case basis.