Comparison of complications in cranioplasty with various materials: a systematic review and meta-analysis

High-Density Porous Polyethylene Implant Cranioplasty: A Systematic Review of Outcomes

Porous polyethylene has been widely used in craniofacial reconstruction due to its biomechanical properties and ease of handling. The objective of this study was to perform a systematic review of the literature to summarize outcomes utilizing high-density porous polyethylene (HDPP) implants in cranioplasty. A literature search of PubMed, Cochrane Library, and Scopus databases was conducted to identify original studies with HDPP cranioplasty from inception to March 2023. Non-English articles, commentaries, absent indications or outcomes, and nonclinical studies were excluded. Data on patient demographics, indications, defect size and location, outcomes, and patient satisfaction were extracted. Summary statistics were calculated using weighted averages based on the available reported data. A total of 1089 patients involving 1104 cranioplasty procedures with HDPP were identified. Patients' mean age was 44.0 years (range 2 to 83 y). The mean follow-up duration was 32.0 months (range 2 wk to 8 y). Two studies comprising 17 patients (1.6%) included only pediatric patients. Alloplastic cranioplasty was required after treatment of cerebrovascular diseases (50.9%), tumor excision (32.0%), trauma (11.4%), trigeminal neuralgia/epilepsy (3.4%), and others such as abscesses/cysts (1.4%). The size of the defect ranged from 3 to 340 cm 2 . An overall postoperative complication rate of 2.3% was identified, especially in patients who had previously undergone surgery at the same site. When data were available, contour improvement and high patient satisfaction were reported in 98.8% and 98.3% of the patients. HDPP implants exhibit favorable outcomes for reconstruction of skull defects. Higher complication rates may be anticipated in secondary cranioplasty cases.

Comprehensive functional outcome analysis and importance of bone remodelling on personalized cranioplasty treatment using Poly(methyl methacrylate) bone flaps

Cranioplasty involves the surgical reconstruction of cranial defects arising as a result of various factors, including decompressive craniectomy, cranial malformations, and brain injury due to road traffic accidents. Most of the modern decompressive craniectomies (DC) warrant a future cranioplasty surgery within 6-36 months. The conventional process of capturing the defect impression and polymethyl methacrylate (PMMA) flap fabrication results in a misfit or misalignment at the site of implantation. Equally, the intra-operative graft preparation is arduous and can result in a longer surgical time, which may compromise the functional and aesthetic outcomes. As part of a multicentric pilot clinical study, we recently conducted a cohort study on ten human subjects during 2019-2022, following the human ethics committee approvals from the participating institutes. In the current study, an important aspect of measuring the extent of bone remodelling during the time gap between decompressive craniectomy and cranioplasty was successfully evaluated. The sterilised PMMA bone flaps were implanted at the defect area during the cranioplasty surgery using titanium mini plates and screws. The mean surgery time was 90 ± 20 min, comparable to the other clinical studies on cranioplasty. No signs of intra-operative and post-operative complications, such as cerebrospinal fluid leakage, hematoma, or local and systemic infection, were clinically recorded. Importantly, aesthetic outcomes were excellent for all the patients, except in a few clinical cases, wherein the PMMA bone flap was to be carefully customized due to the remodelling of the native skull bone. The extent of physiological remodelling was evaluated by superimposing the pre-operative and post-operative CT scan data after converting the defect morphology into a 3D model. This study further establishes the safety and efficacy of a technologically better approach to fabricate patient-specific acrylic bone flaps with improved surgical outcomes. More importantly, the study outcome further demonstrates the strategy to address bone remodelling during the patient-specific implant design.

Cranioplasty Outcomes from a Tertiary Hospital in a Developing Country

BACKGROUND

Decompressive craniectomy (DC) is a surgical procedure to treat refractory increase in intracranial pressure. DC is frequently succeeded by cranioplasty (CP), a reconstructive procedure to protect the underlying brain and maintain cerebrospinal fluid flow dynamics. However, complications such as seizures, fluid collections, infections, and hydrocephalus can arise from CP. Our aim is to investigate these complications and their possible risk factors and to discuss whether early or late CP has any effect on the outcome.

MATERIALS AND METHODS

A single-center retrospective cohort study was performed, including patients who underwent CP after DC between January 2014 and January 2022. Relevant information was collected such as demographics, type of brain injury, materials used in CP, timing between DC and CP, and postoperative complications. Ultimately, 63 patients were included in our study. We also compared the complication rate between patients who underwent late CP after DC (>90 days) against patients who underwent early CP (<90 days).

RESULTS

Most patients were male (78%). The sample median age was 29 years, with pediatric patients, accounting for 36% of the samples. Overall complication rate was 57% and they were seizure/epilepsy in 50% of the patients, fluid collection (28%), infections (25%), posttraumatic hydrocephalus (17%), and bone defect/resorption (3%). Twenty-two percent of patients with complications required reoperation and underwent a second CP. The median (interquartile range) duration between the craniotomy and the CP was 56 (27-102) days, with an early (≤3 months) percentage of 68%. We found no significant difference between early (≤3 months) and late (>3 months) CP regarding complication rates.

CONCLUSION

Despite CP being a simple procedure, it has a considerable rate of complications. Therefore, it is important that surgeons possess adequate knowledge about such complications to navigate these challenges more effectively.

Skull and Scalp En-Bloc Harvest Protects Calvarial Perfusion: A Cadaveric Study

BACKGROUND

 Calvarial defects are severe injuries that can result from a wide array of etiologies. Reconstructive modalities for these clinical challenges include autologous bone grafting or cranioplasty with biocompatible alloplastic materials. Unfortunately, both approaches are limited by factors such as donor site morbidly, tissue availability, and infection. Calvarial transplantation offers the potential opportunity to address skull defect form and functional needs by replacing "like-with-like" tissue but remains poorly investigated.

METHODS

 Three adult human cadavers underwent circumferential dissection and osteotomy to raise the entire scalp and skull en-bloc. The vascular pedicles of the scalp were assessed for patency and perfused with color dye, iohexol contrast agent for computed tomography (CT) angiography, and indocyanine green for SPY-Portable Handheld Imager assessment of perfusion to the skull.

RESULTS

 Gross changes were appreciated to the scalp with color dye, but not to bone. CT angiography and SPY-Portable Handheld Imager assessment confirmed perfusion from the vessels of the scalp to the skull beyond midline.

CONCLUSION

 Calvarial transplantation may be a technically viable option for skull defect reconstruction that requires vascularized composite tissues (bone and soft tissue) for optimal outcomes.

Comparison of Perioperative and Long-term Outcomes Following PEEK and Autologous Cranioplasty: A Single Institution Experience and Review of the Literature

OBJECTIVE

Three-dimensionally (3D) printed polyether-ether-ketone (PEEK) implants are a relatively novel option for cranioplasty that have recently gained popularity. However, there is ongoing debate with respect to material efficacy and safety compared to autologous bone grafts. The purpose of this study was to offer our institution's experience and add to the growing body of literature.

METHODS

A single-institution retrospective analysis of patients undergoing cranioplasties between 2016 and 2021. Patients were divided into PEEK and autologous cranioplasty cohorts. Parameters of interest included patient demographics as well as perioperative (<3 months postoperative) and long-term outcomes (>3 months postoperative). A P value < 0.05 was considered statistically significant.

RESULTS

A total of 31 patients met inclusion criteria (PEEK: 15, Autologous: 16). Mean age of total cohort was 48.9 years (range 19-82 years). Modified Frailty Index (mFI) revealed greater rate of comorbidities among the Autologous group (P = 0.073), which was accounted for in statistical analyses. Multiple logistic regression model revealed significantly higher rate of surgical site infection in the Autologous cohort (31.3% vs. 0%, P = 0.011). Minor complications were similar between groups, while the Autologous group experienced significantly more major postoperative complications (50%) versus PEEK (13.3%) (P = 0.0291). Otherwise perioperative and long term complication profiles were similar between groups. Additionally, generalized linear model demonstrated both cohorts had similar mean hospital length of stay (LoS) (Autologous: 16.1 vs. PEEK: 10.7 days).

CONCLUSIONS

PEEK cranioplasty implants may offer more favorable perioperative complication profiles with similar long-term complication rates and hospital LoS compared to autologous bone implants. Future studies are warranted to confirm our findings in larger series, and further examine the utility of PEEK in cranioplasty.

Evaluation of Vitamin D-enriched Bone Graft in Surgically-induced Critical-sized Bone Defects: An Experimental Study

BACKGROUND

Restoration of bone defects in the craniac vault may require the use of autografts, allografts, xenografts, or synthetic grafts. There are promising data that vitamin D may play a positive role in graft incorporation. The purpose of the present study is the evaluation of the impact of vitamin D addition to human-derived bone grafts in the healing of critical-sized bone defects in porcine skulls.

MATERIALS AND METHODS

Four identical critical-sized defects were created in the calvaria of 8 adult Landrace Large White pigs. The first defect was left blank as control, the second defect was filled with human-derived bone graft, the third defect was filled with human-derived bone graft enriched with a low concentration of vitamin D (2 mg/mL), and the fourth defect was filled with human-derived bone graft enriched with a high concentration of vitamin D (10 mg/mL). The animals were sacrificed after 12 weeks. Harvested tissue specimens were qualitatively evaluated by histology. New bone formation (bone volume/tissue volume) was quantitatively measured by histomorphometry.

RESULTS

Signs of bone formation were evident in all bone sockets. Mean values of the bone volume/tissue volume of the 4 defects were 10.91%, 11.05%, 10.40% and 10.87% respectively, at 12 weeks. In 5 animals, high concentration of vitamin D caused a significant improvement in bone formation in relation to controls. In 3 animals, a high concentration of vitamin D was associated with decreased bone formation compared with controls. No statistical difference was observed in the graft healing among the 4 graft sites ( P > 0.05).

CONCLUSIONS

The results of this study have shown that the addition of vitamin D to human-derived bone grafts does not have a significant effect on bone formation and graft incorporation in critical-sized bone defects of the porcine calvaria. Further high-quality studies are needed to fully elucidate the role of vitamin D in bone formation and bone graft union.

Unveiling the "Kebab" technique: A case report on a two-stage reconstruction method for repeated complex cranioplasty

RATIONALE

Cranioplasty after decompressive craniectomy provides brain protection and improves cerebral hemodynamics. However, recurrent infection and sinking skin flap syndrome after cranioplasty remain cumbersome complications that require a well-planned reconstruction strategy.

PATIENT CONCERNS

A 74-year-old man presented with traumatic subdural hematoma and underwent decompressive craniectomy. Cranioplasty using an original bone flap, bone cement with wires, and a titanium mesh were complicated and resulted in recalcitrant infection and sinking skin flap syndrome.

DIAGNOSES

Recurrent infection and sinking skin flap syndrome post-cranioplasty.

INTERVENTIONS

We designed a two-stage "kebab" reconstruction technique using a combination of free latissimus dorsi myocutaneous flap and delayed non-vascularized free rib graft. A well-vascularized musculocutaneous flap can obliterate dead space in skull defects and reduce bacterial inoculation in deep infections. Subsequently, delayed rib grafts act as the scaffold to expand the sunken scalp flap.

OUTCOMES

At the 3-year follow-up, the patient showed improvement in headache, without evidence of surgical site infection.

LESSONS

The novel "kebab" technique using a combination of a free myocutaneous flap and delayed rib graft can eliminate bacterial growth in infected calvarial defects, reverse sinking skin flap syndrome, and minimize potential donor-site morbidity, and is therefore suitable for patients who require multiple cranioplasties and are unable to withstand major reconstructions.

Perioperative management and prevention of postoperative complications in patients undergoing cranioplasty with polyetheretherketone

OBJECTIVE

This study aimed to compare the incidence of postoperative complications in patients undergoing cranioplasty with polyetheretherketone (PEEK) materials under different perioperative management schemes and summarize and describe a perioperative bundle to reduce patients' postoperative complications and improve patient outcomes.

METHOD

We retrospectively analyzed the clinical data of 69 patients who had undergone craniotomy with PEEK materials in the neurosurgery department of our hospital between June 2017 and June 2021. Patients who had received conventional treatment were defined as the conventional group (29 cases), and those who had received the improved scheme were defined as the improved group (40 cases). The early complications of the two groups were compared, and the long-term effects were observed.

RESULTS

The early total complication rates of the conventional and the improved groups were 55.2% and 32.5%, respectively, without any significant difference (P = 0.06), and the long-term complication rates were 24.1% and 7.5%, respectively, with no significant difference (P = 0.112). The incidence of epidural effusion in the improved group was significantly lower than that in the conventional group, with no significant difference in the incidence of complications, such as intracranial pneumatosis, epidural hemorrhage, new seizures and intracerebral hemorrhage. There was no difference in long-term complications, such as seizures, incision infections, and implant exposure.

CONCLUSION

Epidural effusion after cranioplasty with PEEK materials is common. This study's improved perioperative bundle can effectively reduce the occurrence of epidural effusion after skull repair.

Skull and Scalp En-Bloc Harvest Protects Calvarial Perfusion: A Cadaveric Study

BACKGROUND

 Calvarial defects are severe injuries that can result from a wide array of etiologies. Reconstructive modalities for these clinical challenges include autologous bone grafting or cranioplasty with biocompatible alloplastic materials. Unfortunately, both approaches are limited by factors such as donor site morbidly, tissue availability, and infection. Calvarial transplantation offers the potential opportunity to address skull defect form and functional needs by replacing "like-with-like" tissue but remains poorly investigated.

METHODS

 Three adult human cadavers underwent circumferential dissection and osteotomy to raise the entire scalp and skull en-bloc. The vascular pedicles of the scalp were assessed for patency and perfused with color dye, iohexol contrast agent for computed tomography (CT) angiography, and indocyanine green for SPY-Portable Handheld Imager assessment of perfusion to the skull.

RESULTS

 Gross changes were appreciated to the scalp with color dye, but not to bone. CT angiography and SPY-Portable Handheld Imager assessment confirmed perfusion from the vessels of the scalp to the skull beyond midline.

DISCUSSION/CONCLUSION

 Calvarial transplantation may be a technically viable option for skull defect reconstruction that requires vascularized composite tissues (bone and soft tissue) for optimal outcomes.

Scalp and Calvarium Reconstruction

Defects of the scalp and calvarium pose unique reconstructive challenges due to the importance of this area in protecting the brain and its distance from larger donor vessels for free flap transfer. The wide range and complexity of reconstructive options make this a broad topic because the simplest defects are often closed or managed in the outpatient setting and the most complex require multilayer closure in the operating room with a multidisciplinary team and intensive postoperative care. In hair-bearing individuals, the scalp is an esthetically important area due to the importance of hair to self-esteem and sexual attraction.

Complications and cosmetic outcomes of materials used in cranioplasty following decompressive craniectomy-a systematic review, pairwise meta-analysis, and network meta-analysis

BACKGROUND

Optimal reconstruction materials for cranioplasty following decompressive craniectomy (DC) remain unclear. This systematic review, pairwise meta-analysis, and network meta-analysis compares cosmetic outcomes and complications of autologous bone grafts and alloplasts used for cranioplasty following DC.

METHOD

PubMed, Embase, and Cochrane were searched from inception until April 2021. A random-effects pairwise meta-analysis was used to compare pooled outcomes and 95% confidence intervals (CIs) of autologous bone to combined alloplasts. A frequentist network meta-analysis was subsequently conducted to compare multiple individual materials.

RESULTS

Of 2033 articles screened, 30 studies were included, consisting of 29 observational studies and one randomized control trial. Overall complications were statistically significantly higher for autologous bone compared to combined alloplasts (RR = 1.56, 95%CI = 1.14-2.13), hydroxyapatite (RR = 2.60, 95%CI = 1.17-5.78), polymethylmethacrylate (RR = 1.50 95%CI = 1.08-2.08), and titanium (Ti) (RR = 1.56 95%CI = 1.03-2.37). Resorption occurred only in autologous bone (15.1%) and not in alloplasts (0.0%). When resorption was not considered, there was no difference in overall complications between autologous bone and combined alloplasts (RR = 1.00, 95%CI = 0.75-1.34), nor between any individual materials. Dehiscence was lower for autologous bone compared to combined alloplasts (RR = 0.39, 95%CI = 0.19-0.79) and Ti (RR = 0.34, 95%CI = 0.15-0.76). There was no difference between autologous bone and combined alloplasts with respect to infection (RR = 0.85, 95%CI = 0.56-1.30), migration (RR = 1.36, 95%CI = 0.63-2.93), hematoma (RR = 0.98, 95%CI = 0.53-1.79), seizures (RR = 0.83, 95%CI = 0.29-2.35), satisfactory cosmesis (RR = 0.88, 95%CI = 0.71-1.08), and reoperation (RR = 1.66, 95%CI = 0.90-3.08).

CONCLUSIONS

Bone resorption is only a consideration in autologous cranioplasty compared to bone substitutes explaining higher complications for autologous bone. Dehiscence is higher in alloplasts, particularly in Ti, compared to autologous bone.

Clinical Applications of Poly-Methyl-Methacrylate in Neurosurgery: The In Vivo Cranial Bone Reconstruction

Background: Biomaterials and biotechnology are becoming increasingly important fields in modern medicine. For cranial bone defects of various aetiologies, artificial materials, such as poly-methyl-methacrylate, are often used. We report our clinical experience with poly-methyl-methacrylate for a novel in vivo bone defect closure and artificial bone flap development in various neurosurgical operations. Methods: The experimental study included 12 patients at a single centre in 2018. They presented with cranial bone defects after various neurosurgical procedures, including tumour, traumatic brain injury and vascular pathologies. The patients underwent an in vivo bone reconstruction from poly-methyl-methacrylate, which was performed immediately after the tumour removal in the tumour group, whereas the trauma and vascular patients required a second surgery for cranial bone reconstruction due to the bone decompression. The artificial bone flap was modelled in vivo just before the skin closure. Clinical and surgical data were reviewed. Results: All patients had significant bony destruction or unusable bone flap. The tumour group included five patients with meningiomas destruction and the trauma group comprised four patients, all with severe traumatic brain injury. In the vascular group, there were three patients. The average modelling time for the artificial flap modelling was approximately 10 min. The convenient location of the bone defect enabled a relatively straightforward and fast reconstruction procedure. No deformations of flaps or other complications were encountered, except in one patient, who suffered a postoperative infection. Conclusions: Poly-methyl-methacrylate can be used as a suitable material to deliver good cranioplasty cosmesis. It offers an optimal dural covering and brain protection and allows fast intraoperative reconstruction with excellent cosmetic effect during the one-stage procedure. The observations of our study support the use of poly-methyl-methacrylate for the ad hoc reconstruction of cranial bone defects.

Comparison of autograft and implant cranioplasty in pediatrics: A meta-analysis

Background:

Cranioplasty in pediatrics is quite challenging and intricated. The ideal material for it is still debatable until now due to the limited study comparing autologous and implant grafts. This meta-analytic study was conducted to evaluate the risk of infection and revision in pediatric patients after autograft and implant cranioplasty.

Methods:

A systematic review and meta-analysis were performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. A thorough literature search was conducted on PubMed, Cochrane, Scopus, and ScienceDirect database. Articles published from 2000 to 2021 were selected systematically using PRISMA based on the predetermined eligibility criteria. The relevant data were, then, analyzed and discussed.

Results:

A total of four publications investigating the outcome of autograft and implant cranioplasty were included and reviewed. Postoperative infection and revision rate after 126 cranioplasty procedures (both autograft or implant) from 119 patients below 21 years during time frame of study were analyzed. This meta-analysis study showed that the rate of infection and revision after cranioplasty were not different between the autograft and implant groups.

Conclusion:

Autograft and implant cranioplasty have no significant difference in postoperatively infection and revision rate. This study showed that cranioplasty using implant is a plausible option in pediatric patients with cranial defects, depending on the patients’ condition due to similar outcome with autograft cranioplasty. Further studies with larger population and more specific details are necessary to determine the comparison of autograft and implant material in cranioplasty procedure.

Outcomes and Associated Complications of Cranioplasty following Craniectomy in Brunei Darussalam

Objective Cranioplasty, commonly performed after decompressive craniectomy, is associated with significant complications. We aim to characterize the outcomes and complications post cranioplasty performed in Brunei Darussalam.

Methods and Materials We conducted a nationwide retrospective study of the patients who underwent cranioplasty. Patients who underwent cranioplasty by the Neurosurgical Department from January 2014 to June 2019 were included. Patients were excluded if they did not have a minimum of 30-days follow-up or the initial cranioplasty was performed elsewhere. Outcomes including complications post cranioplasty and 30-day and 1-year failure rates were assessed. All statistical analyses were performed with SPSS version 20 (IBM Corporation, Armonk, New York, USA). The χ2 test, Student's t-test, and the Mann–Whitney U test were performed for nominal, normally, and non-normally distributed variables, respectively. Multivariate logistic regression was used to assess predictors for complications and cranioplasty failure.

Results Seventy-seven patients with a median age of 48 (interquartile range, 37–61) years were included. Most cranioplasties used autologous bone (70/77, 90.9%). Infection and overall complication rates were 3.9% and 15.6%, respectively. Cranioplasty failure (defined as removal or revision of cranioplasty) rate was 9.1%. Previous cranial site infection post craniectomy was associated with cranioplasty failure (odds ratio: 12.2, 95% confidence interval [1.3, 114.0], p=0.028).

Conclusions Cranioplasty is generally associated with significant complications, including reoperation for implant failure. We highlighted that autologous bone cranioplasties can be performed with an acceptable low rate of infection, making it a viable first option for implant material.

Subgaleal Effusion and Brain Midline Shift After Cranioplasty: A Retrospective Study Between Polyetheretherketone Cranioplasty and Titanium Cranioplasty After Decompressive Craniectomy

Cranioplasty with polyetheretherketone (PEEK) has recently shown better cerebral protection performance, improved brain function, and aesthetic contour compared with titanium mesh. However, whether patients undergoing PEEK cranioplasty tend to develop subgaleal effusions remains elusive. This retrospective study included patients who underwent cranioplasty with PEEK implants or titanium mesh after decompressive craniectomy between July 2017 and July 2020. Patient information, including general information, location, size of the defect, subgaleal depth, and brain midline shift was collected and statistically analyzed. There were 130 cases of cranioplasty, including 35 with PEEK implants and 95 with a titanium mesh. Patients who underwent cranioplasty with a PEEK implant had a higher subgaleal effusion rate than those who underwent cranioplasty with titanium mesh (85.71% vs. 53.68%, P < 0.001), while a midline shift >5 mm was more frequently observed in the PEEK group than in the titanium group (20% vs. 6.3%, P = 0.021). The PEEK material was the only factor associated with subgaleal effusion after cranioplasty (OR 5.589, P = 0.002). Logistic regression analysis further showed that age was a protective factor against midline shift in the PEEK cranioplasty group (OR 0.837, P = 0.029). Patients who underwent cranioplasty with PEEK implants were more likely to develop severe subgaleal effusion and significant brain midline shifts than those with titanium mesh implants.

Decompressive hemicraniectomy and cranioplasty using subcutaneously preserved autologous bone flaps versus synthetic implants: perioperative outcomes and cost analysis

OBJECTIVE

It has not been well-elucidated whether there are advantages to preserving bone flaps in abdominal subcutaneous (SQ) tissue after decompressive hemicraniectomy (DHC), compared to discarding bone flaps. The authors aimed to compare perioperative outcomes and costs for patients undergoing autologous cranioplasty (AC) after DHC with the bone flap preserved in abdominal SQ tissue, and for patients undergoing synthetic cranioplasty (SC).

METHODS

A retrospective review was performed of all patients undergoing DHC procedures between January 2017 and July 2021 at two tertiary care institutions. Patients were divided into two groups: those with flaps preserved in SQ tissue (SQ group), and those with the flap discarded (discarded group). Additional analysis was performed between patients undergoing AC versus SC. Primary end points included postoperative and surgical site complications. Secondary endpoints included operative costs, length of stay, and blood loss.

RESULTS

A total of 248 patients who underwent DHC were included in the study, with 155 patients (62.5%) in the SQ group and 93 (37.5%) in the discarded group. Patients in the discarded group were more likely to have a diagnosis of severe TBI (57.0%), while the most prevalent diagnosis in the SQ group was malignant stroke (35.5%, p < 0.05). There were 8 (5.2%) abdominal surgical site infections and 9 (5.8%) abdominal hematomas. The AC group had a significantly higher reoperation rate (23.2% vs 12.9%, p = 0.046), with 11% attributable to abdominal reoperations. The average cost of a reoperation for an abdominal complication was $40,408.75 ± $2273. When comparing the AC group to the SC group after cranioplasty, there were no significant differences in complications or surgical site infections. There were 6 cases of significant bone resorption requiring cement supplementation or discarding of the bone flap. Increased mean operative charges were found for the SC group compared to the AC group ($72,362 vs $59,726, p < 0.001).

CONCLUSIONS

Autologous bone flaps may offer a cost-effective option compared to synthetic flaps. However, when preserved in abdominal SQ tissue, they pose the risk of resorption over time as well as abdominal surgical site complications with increased reoperation rates. Further studies and methodologies such as cryopreservation of the bone flap may be beneficial to reduce costs and eliminate complications associated with abdominal SQ storage.

A Perioperative Paradigm of Cranioplasty With Polyetheretherketone: Comprehensive Management for Preventing Postoperative Complications

Introduction

At present, lots of studies have discussed the effects and outcomes of cranioplasty using polyetheretherketone (PEEK). However, interventions or management for PEEK cranioplasty got less attention. This article presented a perioperative paradigm for preventing postoperative complications.

Materials and Methods

Modified PEEK plates with certified safety were implanted in patients who received evolving perioperative paradigm. Serial perioperative managements were developed as a comprehensive paradigm to prevent correlated risk factors of postoperative complications, which mainly included managements of epidural collections and wound healing. The preparation of the surgical area and systemic state were essential before surgery. During the operation, the blood supply of the incision and the handling of dura and temporalis were highlighted in our paradigm. After cranioplasty, management of subcutaneous drainage and wound healing were stressed. Patients received conventional management from February 2017 to August 2018 in our center. After the evolving paradigm developed, patients received comprehensive perioperative management from September 2018 to August 2020.

Results

A total of 104 patients who underwent PEEK cranioplasty were consecutively enrolled; 38 (36.5%) received conventional perioperative management, and 66 (63.5%) received evolving perioperative paradigm. The general information of the two groups was comparable. Notably, patients who received the evolving paradigm presented a significantly decreased incidence of postoperative complications from 47.4 to 18.2% (P < 0.01), among which the incidences of subcutaneous effusion, epidural hematoma, and subcutaneous infection decreased significantly.

Conclusion

The evolving perioperative paradigm could effectively prevent risk factors and reduce related complications. It was valuable to promote these comprehensive managements and inspire more clinical practice on improving patients' outcomes after PEEK cranioplasty.

A Narrative Review of Cell-Based Approaches for Cranial Bone Regeneration

Current cranial repair techniques combine the use of autologous bone grafts and biomaterials. In addition to their association with harvesting morbidity, autografts are often limited by insufficient quantity of bone stock. Biomaterials lead to better outcomes, but their effectiveness is often compromised by the unpredictable lack of integration and structural failure. Bone tissue engineering offers the promising alternative of generating constructs composed of instructive biomaterials including cells or cell-secreted products, which could enhance the outcome of reconstructive treatments. This review focuses on cell-based approaches with potential to regenerate calvarial bone defects, including human studies and preclinical research. Further, we discuss strategies to deliver extracellular matrix, conditioned media and extracellular vesicles derived from cell cultures. Recent advances in 3D printing and bioprinting techniques that appear to be promising for cranial reconstruction are also discussed. Finally, we review cell-based gene therapy approaches, covering both unregulated and regulated gene switches that can create spatiotemporal patterns of transgenic therapeutic molecules. In summary, this review provides an overview of the current developments in cell-based strategies with potential to enhance the surgical armamentarium for regenerating cranial vault defects.

Extended Scalp Expansion for Larger Defects During Staged Cranioplasty

BACKGROUND

Secondary cranioplasty is often required following trauma, infection, radiation, or oncologic care, but is complicated by soft-tissue deficits with limited regional options. Scalp tissue expanders can provide hair-bearing, vascularized tissue for tension-free closure yielding optimal aesthetic results. However, the upper limit of safe scalp expansion has not been explored. This study sought to evaluate the efficacy of extended scalp tissue expansion for challenging cranioplasties in a consecutive series.

METHODS

Patients who underwent scalp tissue expansion before cranioplasty were retrospectively identified from a single institution between the years 2017 and 2020. Patient demographics, tissue expansion characteristics, and complications during expansion and after cranioplasty were collected.

RESULTS

Six patients were identified who underwent staged scalp expansion for cranioplasty; 5 were male (83.3%) with a mean age of 43.8 ± 12.5 years. Indications for cranioplasty included 2 epilepsy-related procedures, 1 oligodendroglioma, 2 infectious processes, and 1 traumatic incident. A single expander was used in 5 cases, whereas 2 were used in the remaining case. The average expander fill volume was 434.3 ± 115 ccs with a mean expansion time of 3.3 ± 1.4 months. Expander infection occurred in 1 case and expander exposure in another, but adequate scalp expansion was still achieved in both. Successful closure over cranioplasty was obtained in 5 cases (83.3%); 1 patient ultimately required free flap reconstruction for soft-tissue coverage.

CONCLUSIONS

In cases of extended scalp defects, scalp tissue expansion remains the preferred method for recruiting large quantities of like tissue before implant cranioplasty.

Quantitative assessment and localization of the hollowing of the temple after craniectomy and cranioplasty-The frontozygomatic shadow

Background

After cranioplasty, in many cases a not negligible soft tissue defect remains in the temporozygomatical area, also referred to as a hollowing defect of the temple.

Objective

To assess the precise localization and volume of the hollowing defect, to optimize future cranioplasties.

Methods

CT data of patients who received craniectomy and conventional CAD cranioplasty in our institution between 2012 and 2018 were analyzed. CT datasets prior to craniectomy and after cranioplasty were subtracted to quantify the volume and localization of the defect.

Results

Out of 91 patients, 21 had suitable datasets. Five cases had good cosmetic results with no defect visible, 16 patients had an apparent hollowing defect. Their average defect volume was 5.0 cm³ ± 4.5 cm³. The defect localizations were in the area behind the zygomatic process and just below the superior temporal line, covering an area of app. 3x3 cm². Surgical attempts of temporal muscle restoration were more often found in reports of good results (p<0.01), but also in 50% of reports, whose surgeries resulted in hollowing of the temple. Mean time between the two surgeries was 112 ± 43 days. No significant differences between patients with and without hollowing defect were detected regarding time between the two surgeries, age or performing surgeon.

Conclusion

This work supplies evidence for the indication of a surgical corrective during cranioplasty in the small but cosmetically relevant area of the “frontozygomatic shadow”. Based on our 3D data analysis, future focused surgical strategies may obtain better aesthetical results here.

Characterizing Adverse Events of Cranioplasty Implants After Craniectomy: A Retrospective Review of the Federal Manufacturer and User Facility Device Experience Database

Introduction

Cranioplasty is performed by placing an artificial plate in place of a patient's native skull bones to repair post-craniectomy defects after trauma. Implanted materials can range from titanium to synthetic polyether derivatives and are produced by multiple manufacturers. There are few studies characterizing complications associated with these cranioplasty plates to date. We aimed to quantify and categorize complications of these devices using a national federal database.

Methods

The Manufacturer and User Facility Device Experience (MAUDE) database was queried for all entries reported under the category "plate, cranioplasty, preformed, non-alterable" with the additional product code GXN between the time range from September 1, 2010, to September 1, 2020. After data extraction, each of the entries was screened for duplicates and tabulated into different categories of complications. Additionally, product information such as the plate manufacturer was extracted from each entry.

Results

The search yielded 329 unique event reports. The most frequent complications were infection (39%), followed by incorrectly fitting implants (30%) and implant breaks (6%). Other major complications included cerebrospinal fluid leakage and cerebral edema (5%), wound dehiscence (5%), and migration of hardware (3%). The brands associated with the most entries in the database were the Synthes (DePuy Synthes Companies, Massachusetts, United States) polyetheretherketone (PEEK) patient-specific implants (PSI) (57%), the Biomet (Zimmer Biome, Indiana, United States) hard tissue replacement-polyetherketoneketone (HTR-PEKK) patient-matched implant (PMI) (23%), and the AccuShape PEEK PSI (MedCAD, Dallas, USA) (5%).

Conclusions

Infection and improperly fitting implants appear to be the two most frequent complications of cranioplasty plates. The goals of future research should include the prevention of plate infections as well as improving techniques to custom-fit implantable devices.

First Report of a Multicenter Prospective Registry of Cranioplasty in the United Kingdom and Ireland

BACKGROUND

There are many questions that remain unanswered regarding outcomes following cranioplasty including the timing of cranioplasty following craniectomy as well as the material used.

OBJECTIVE

To establish and evaluate 30-d outcomes for all cranial reconstruction procedures in the United Kingdom (UK) and Ireland through a prospective multicenter cohort study.

METHODS

Patients undergoing cranioplasty insertion or revision between June 1, 2019 and November 30, 2019 in 25 neurosurgical units were included. Data collected include demographics, craniectomy date and indication, cranioplasty material and date, and 30-d outcome.

RESULTS

In total, 313 operations were included, consisting of 255 new cranioplasty insertions and 58 revisions. Of the new insertions, the most common indications for craniectomy were traumatic brain injury (n = 110, 43%), cerebral infarct (n = 38, 15%), and aneurysmal subarachnoid hemorrhage (n = 30, 12%). The most common material was titanium (n = 163, 64%). Median time to cranioplasty was 244 d (interquartile range 144-385), with 37 new insertions (15%) within or equal to 90 d. In 30-d follow-up, there were no mortalities. There were 14 readmissions, with 10 patients sustaining a wound infection within 30 d (4%). Of the 58 revisions, the most common reason was due to infection (n = 33, 59%) and skin breakdown (n = 13, 23%). In 41 (71%) cases, the plate was removed during the revision surgery.

CONCLUSION

This study is the largest prospective study of cranioplasty representing the first results from the UK Cranial Reconstruction Registry, a first national registry focused on cranioplasty with the potential to address outstanding research questions for this procedure.

Complications of Cranioplasty in Relation to Material: Systematic Review, Network Meta-Analysis and Meta-Regression

BACKGROUND

Cranioplasty is a ubiquitous neurosurgical procedure consisting of reconstruction of a pre-existing calvarial defect. Many materials are available, including polymethylmethacrylate in hand-moulded (hPMMA) and prefabricated (pPMMA) form, hydroxyapatite (HA), polyetheretherketone (PEEK) and titanium (Ti).

OBJECTIVE

To perform a network meta-analysis (NMA) to assess the relationship between materials and complications of cranioplasty.

METHODS

PubMed/MEDLINE, Google Scholar, EMBASE, Scopus, and The Cochrane Library were searched from January 1, 1990 to February 14, 2021. Studies detailing rates of any of infections, implant exposure, or revision surgery were included. A frequentist NMA was performed for each complication. Risk ratios (RRs) with 95% CIs were calculated for each material pair.

RESULTS

A total of 3620 abstracts were screened and 31 full papers were included. Surgical revision was reported in 18 studies and occurred in 316/2032 cases (14%; 95% CI 11-17). PEEK had the lowest risk of re-operation with a rate of 8/157 (5%; 95% CI 0-11) in 5 studies, superior to autografts (RR 0.20; 95% CI 0.07-0.57), hPMMA (RR 0.20; 95% CI 0.07-0.60), Ti (RR 0.39; 95% CI 0.17-0.92), and pPMMA (RR 0.14; 95% CI 0.04-0.51). Revision rate was 131/684 (19%; 95% CI 13-25; 10 studies) in autografts, 61/317 (18%; 95%CI 9-28; 7 studies) in hPMMA, 84/599 (13%; 95% CI 7-19; 11 studies) in Ti, 7/59 (9%; 95% CI 1-23; 3 studies) in pPMMA, and 25/216 (12%; 95% CI 4-24; 4 studies) in HA. Infection occurred in 463/4667 (8%; 95% CI 6-11) and implant exposure in 120/1651 (6%; 95% CI 4-9).

CONCLUSION

PEEK appears to have the lowest risk of cranioplasty revision, but further research is required to determine the optimal material.

The Influence of Hyaluronic Acid Biofunctionalization of a Bovine Bone Substitute on Osteoblast Activity In Vitro

Bovine bone substitute materials (BSMs) are used for oral bone regeneration. The objective was to analyze the influence of BSM biofunctionalization via hyaluronic acid (HA) on human osteoblasts (HOBs). BSMs with ± HA were incubated with HOBs including HOBs alone as a negative control. On days 3, 7 and 10, cell viability, migration and proliferation were analyzed by fluorescence staining, scratch wound assay and MTT assay. On days 3, 7 and 10, an increased cell viability was demonstrated for BSM+ compared with BSM− and the control (each p ≤ 0.05). The cell migration was enhanced for BSM+ compared with BSM− and the control after day 3 and day 7 (each p ≤ 0.05). At day 10, an accelerated wound closure was found for the control compared with BSM+/− (each p < 0.05). The highest proliferation rate was observed for BSM+ on day 3 (p ≤ 0.05) followed by BSM− and the control (each p ≤ 0.05). At day 7, a non-significantly increased proliferation was shown for BSM+ while the control was higher than BSM− (each p < 0.05). The least proliferation activity was observed for BSM− (p < 0.05) at day 10. HA biofunctionalization of the BSMs caused an increased HOB activity and might represent a promising alternative to BSM− in oral bone regeneration.

Complications of cranioplasty following decompressive craniectomy for traumatic brain injury: systematic review and meta-analysis

BACKGROUND

Decompressive craniectomy (DC) is a common neurosurgical intervention for severe traumatic brain injury (TBI), as well as malignant stroke, malignancy and infection. DC necessitates subsequent cranioplasty. There are significant demographic differences between TBI and non-TBI patients undergoing cranioplasty, which may influence their relative risk profiles for infection, aseptic bone flap resorption (aBFR) and re-operation.

OBJECTIVE

Perform a meta-analysis to determine the relative infection, aBFR and re-operation risk profiles of TBI patients as compared to other indications for DC.

METHODS

A systematic review and meta-analysis was performed in accordance with the PRISMA guidelines. PubMed, MEDLINE, EMBASE and Google Scholar were searched until 26/11/2020. Studies detailing rates of infection, re-operation and/or aBFR in specific materials and the post-TBI population were included, while studies in paediatrics or craniosynostosis repair were excluded.

RESULTS

Twenty-six studies were included. There was no difference in relative risk of infection between TBI and non-TBI cohorts (RR 0.81, 95% CI 0.57-1.17), with insignificant heterogeneity (I² = 33%). TBI was a risk factor for aBFR (RR 1.54, 95% CI 1.25-1.89), with no significant heterogeneity (I² = 13%). TBI was a risk factor for re-operation in the autologous sub-group (RR 1.49, 95% CI 1.05-2.11) but not in the alloplastic sub-group (RR = 0.86, 95% CI 0.34-2.18). Heterogeneity was insignificant (I² = 11%).

CONCLUSION

TBI is a risk factor for aBFR and re-operation following cranioplasty. Use of an alloplastic graft for primary cranioplasty in these patients may partially mitigate this increased risk.