The therapeutic effect of patient-specific implants in cranioplasty

Is Polyetheretherketone an Effective Alloplastic Material in Comparison to Titanium in Calvarial Reconstruction

INTRODUCTION AND AIM

Polyetheretherketone (PEEK) and titanium (Ti) cranioplasty implants ideal outcomes are good esthetics, long-term stability, and protection of the fragile brain tissue. However, it is unclear whether PEEK implants can offer an equal alternative to Ti implants. This work aimed to critically review papers and case series published on both Ti and PEEK Cranioplasty regarding complications, clinical outcomes, ease of use, esthetics, manufacture and availability, cost and time-saving factors, postoperative quality of life (QOL), as well as their suitability for the fronto-orbito region reconstruction.

METHODS

PubMed database was sourced for published literature in the period 2007 to the end of 2023; a further manual search for articles was carried out on the reference lists of each paper.

RESULTS

A total of 48980 papers were found during the initial search, but only 33 articles met the inclusion criteria. A total of 6023 cranial implants, with 3879 being Ti and 1205 PEEK. Titanium was the material of choice in over 64.4% of cases; however, Ti has been in application for many years compared to PEEK. Out of the 33 papers, there was 27 retrospective cohort/analysis/case series and reviews: 1 meta-analysis, 2 systematic reviews and 3 randomized control trials. Four articles commented on the QOL, 15 on esthetics, 7 discussed cost and time-saving without measurable variables, and 7 articles looked explicitly at the complex fronto-orbito region, of which 49% were primary 1-stage surgical reconstructions, 54% were reconstructed with PEEK and 7% Ti (CAD/CAM).

CONCLUSION

There is no absolute consensus for the preference of either material, however, in the fronto-orbito region, PEEK is the material of choice for ease of use, esthetics, and time-saving. However, there are no long-term studies on PEEK cranioplasty, and fewer in comparison with Ti implants. Further research is required in this field. No reliable or measurable data was found to determine the QOL, esthetics, cost, or time-saving elements.

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.

Can we do better at measuring patient-reported outcomes after cranioplasty? A systematic review

Measuring quality of life (QOL) after cranioplasty is increasingly evident as a necessary component of patient-centered care. For data to be useful in clinical decision-making and approval of new therapies, studies must utilize valid and reliable instruments. Our objective was to critically appraise studies evaluating QOL in adult cranioplasty patients and determine validity and relevance of the patient-reported outcome measures (PROMs) used. Electronic databases of PubMed, Embase, CINAHL, and PsychINFO were used to identify PROMs measuring QOL in adult patients with cranioplasty. The methodological approach, cranioplasty outcomes, and domains measured by the PROMs were extracted and summarized descriptively. A content analysis of the identified PROMs was completed to identify the concepts measured. From 2236 articles identified, 17 articles containing eight QOL PROMs met the inclusion criteria. None of the PROMs was specifically validated or developed for adults undergoing cranioplasty. The QOL domains included physical health, psychological health, social health, and general QOL. These four domains encompassed 216 total items among the PROMs. Appearance was only assessed in two PROMs. To our knowledge, there are currently no validated PROMs that comprehensively measure appearance, facial function, and adverse effects in adults undergoing cranioplasty. There is an urgent need to develop PROMs to measure QOL outcomes rigorously and comprehensively in this patient population to inform clinical care, research, and quality improvement initiatives. Findings from this systematic review will be used to derive an outcome instrument containing important concepts related to QOL in patients who undergo cranioplasty.

Outcomes of Cranioplasty Strategies for High-Risk Complex Cranial Defects: A 10-Year Experience

INTRODUCTION

Although the literature contains reports of the risks and complications of calvarial vault reconstruction for acquired defects, there are few publications addressing the specific patient population who require such reconstructions in cases preceded by prior infection, radiation, massive associated soft tissue trauma, and so on. We define such clinical presentations as a hostile environment for large surface area reconstruction. Our objective is to compare the safety and efficacy of autologous bone and alloplastic reconstruction in hostile cranial defects.

METHODS

An institutional review board-approved retrospective review of patients who underwent cranioplasty of a hostile site at the University of Alabama at Birmingham between January 2008 and December 2018 was performed. The patients were stratified into 3 groups based on the type of implant used: autogenous (bone), alloplastic (polyetheretherketone [PEEK], titanium, polymethyl methacrylate), or mixed (combination of bone and prosthetic). The primary outcome metric was a complication in the year after cranioplasty, identified by implant failure, necrosis, or infection. Statistical analysis included t tests and χ2 tests where appropriate using SPSS.

RESULTS

There were 55 total cases in this period: 27 autogenous, 23 alloplastic, and 5 mixed. The purely autogenous group had the highest complication rate (44%), and the alloplastic group had the lowest complication rate (38%), which was not statistically different between the 3 groups (P = 0.121). When stratified by specific material used for reconstruction (27 bone, 14 PEEK, 10 titanium, and 5 polymethyl methacrylate), overall complication rate was statistically significant (P = 0.009, χ2 test), with PEEK implants having the lowest complication rate (21%).

CONCLUSIONS

This analysis interestingly found that in the setting of hostile cranial defects, cranioplasties would benefit from the use of prosthetic implants instead of autologous bone grafts, not only for avoidance of donor site morbidity but also for a decrease in overall complications.

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.

Evaluation of the Fitting Accuracy of CAD/CAM-Manufactured Patient-Specific Implants for the Reconstruction of Cranial Defects-A Retrospective Study

Cranioplasties show overall high complication rates of up to 45.3%. Risk factors potentially associated with the occurrence of postoperative complications are frequently discussed in existing research. The present study examines the positioning of 39 patient-specific implants (PSI) made from polyetheretherketone (PEEK) and retrospectively investigates the relationship between the fitting accuracy and incidence of postoperative complications. To analyze the fitting accuracy of the implants pre- and post-operatively, STL files were created and superimposed in a 3D coordinate system, and the deviations were graphically displayed and evaluated along with the postoperative complications. On average, 95.17% (SD = 9.42) of the measurements between planned and surgically achieved implant position were within the defined tolerance range. In cases with lower accordance, an increased occurrence of complications could not be demonstrated. The overall postoperative complication rate was 64.1%. The fitting of the PEEK-PSI was highly satisfactory. There were predominantly minor deviations of the achieved compared to the planned implant positions; however, estimations were within the defined tolerance range. Despite the overall high accuracy of fitting, a considerable complication rate was found. To optimize the surgical outcome, the focus should instead be directed towards the investigation of other risk factors.

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.

Trends and Outcomes of Cranioplasty Alone Versus Single-Stage Composite Scalp and Calvarial Reconstruction

BACKGROUND

Cranioplasty is a critical intervention to restore the calvarium using autologous or alloplastic materials with single-stage composite scalp and calvarial reconstruction reserved for complex cases. This study aims to identify 30-day outcomes in scalp and calvarial reconstruction using the American College of Surgeons National Surgical Quality Improvement Program database.

METHODS

The authors conducted a retrospective analysis of the 2010 to 2018 American College of Surgeons National Surgical Quality Improvement Program database. Adult patients who underwent cranioplasty were identified using current procedural terminology coding and included by exposure type (autologous, alloplastic, composite, or other). Subjects with missing exposure or outcome data were excluded. Primary outcome was 30-day reoperation, whereas secondary outcomes were 30-day unplanned readmission and transfusion. Univariate analysis was completed to assess differences in demographics, comorbidities, and postoperative complications. Multivariable logistic regression was used to control for confounders.

RESULTS

In total, 1719 patients underwent cranioplasty (mean age 54.7 ± 15.3 years, 43.5% male), including 169(9.8%) autologous, 1303(75.8%) alloplastic, 32(1.9%) composite, and 215(12.5%) other procedures. Cranioplasty procedures were associated with 30-day complication and mortality rate of 16.5% and 2.4%, respectively. Composite cranioplasty was associated with decreased 30-day reoperation (adjusted odds ratios 0.11, 95% confidence interval 0.014-0.94, P = 0.044). There was no statistically significant difference in readmission between cranioplasty groups. Alloplastic cranioplasty was associated with decreased odds of postoperative transfusion (adjusted odds ratios 0.47, 95% confidence interval 0.27-0.84, P = 0.01).

CONCLUSIONS

Cranioplasty is an increasingly common procedure. Alloplastic cranioplasty is associated with decreased 30-day transfusion requirement, whereas single-stage composite reconstruction is a viable option and associated with decreased 30-day reoperation with no difference in readmission.

Evaluation of a self-fitting, shape memory polymer scaffold in a rabbit calvarial defect model

Self-fitting scaffolds prepared from biodegradable poly(ε-caprolactone)-diacrylate (PCL-DA) have been developed for the treatment of craniomaxillofacial (CMF) bone defects. As a thermoresponsive shape memory polymer (SMP), with the mere exposure to warm saline, these porous scaffolds achieve a conformal fit in defects. This behavior was expected to be advantageous to osseointegration and thus bone healing. Herein, for an initial assessment of their regenerative potential, a pilot in vivo study was performed using a rabbit calvarial defect model. Exogenous growth factors and cells were excluded from the scaffolds. Key scaffold material properties were confirmed to be maintained following gamma sterilization. To assess scaffold integration and neotissue infiltration along the defect perimeter, non-critically sized (d = 8 mm) bilateral calvarial defects were created in 12 New Zealand white rabbits. Bone formation was assessed at 4 and 16 weeks using histological analysis and micro-CT, comparing defects treated with an SMP scaffold (d = 9 mm x t = 1 or 2 mm) to untreated defects (i.e. defects able to heal without intervention). To further assess osseointegration, push-out tests were performed at 16 weeks and compared to defects treated with poly(ether ether ketone) (PEEK) discs (d = 8.5 mm x t = 2 mm). The results of this study confirmed that the SMP scaffolds were biocompatible and highly conducive to bone formation and ingrowth at the perimeter. Ultimately, this resulted in similar bone volume and surface area versus untreated defects and superior performance in push-out testing versus defects treated with PEEK discs. STATEMENT OF SIGNIFICANCE: Current treatments of craniomaxillofacial (CMF) bone defects include biologic and synthetic grafts but they are limited in their ability to form good contact with adjacent tissue. A regenerative engineering approach using a biologic-free scaffold able to achieve conformal fitting represents a potential "off-the-shelf" surgical product to heal CMF bone defects. Having not yet been evaluated in vivo, this study provided the preliminary assessment of the bone healing potential of self-fitting PCL scaffolds using a rabbit calvarial defect model. The study was designed to assess scaffold biocompatibility as well as bone formation and ingrowth using histology, micro-CT, and biomechanical push-out tests. The favorable results provide a basis to pursue establishing self-fitting scaffolds as a treatment option for CMF defects.

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.

Digitally designed, personalized bone cement spacer for staged TMJ and mandibular reconstruction - Introduction of a new technique

The aim of this paper is to introduce an innovative workflow for staged reconstruction of the mandible, including the temporomandibular joint (TMJ), using a temporary, patient-specific spacer. In cases of partial mandibular resection including disarticulation, sometimes needed to treat inflammatory bone disease, the spacer is intended to retain symmetry of the hard tissues, to preserve the soft tissues, and to act as a bactericidal agent. When complete healing of the affected surrounding tissues has occurred, final reconstruction using a patient-matched total TMJ endoprosthesis, in combination with an autogenous free bone flap, can be performed as a second-stage procedure. The crucial steps of the workflow are virtual surgical planning, manufacturing of a two-part silicone mold, and chairside manufacturing of the spacer using an established bone cement with gentamycin. The method was first introduced in two patients suffering from therapy-resistant chronic osteomyelitis. The presented protocol of staged surgery allows a much safer and predictable reconstruction compared with immediate reconstruction. The workflow also minimizes the potential risk of endoprosthesis infection - one of the major risks of implant failure.

Biomechanical evaluation of a customized 3D-printed polyetheretherketone condylar prosthesis

The present study aimed to evaluate the biomechanical behavior of a custom 3D-printed polyetheretherketone (PEEK) condylar prosthesis using finite element analysis and mechanical testing. The Mimics software was used to create a 3D model of the mandible, which was then imported into Geomagic Studio software to perform osteotomy of the lesion area. A customized PEEK condyle prosthesis was then designed and the finite element model of the PEEK condyle prosthesis, mandible and fixation screw was established. The maximum stress of the prosthesis and screws, as well as stress and strain of the cortical and cancellous bones in the intercuspal position, incisal clench, left unilateral molar clench and right unilateral molar clench was analyzed. The biomechanical properties of the prosthesis were studied using two models with different lesion ranges. To simulate the actual clinical situation, a special fixture was designed. The compression performance was tested at 1 mm/min for the condyle prosthesis, prepared by fused deposition modeling (FDM). The results of a finite element analysis suggested that the maximum stress of the condyle was 10.733 MPa and the maximum stress of the screw was 9.7075 MPa; both were far less than the yield strength of the material. The maximum force that the two designed prostheses were able to withstand was 3,814.7±442.6 N (Model A) and 4,245.7±348.3 N (Model B). Overall, the customized PEEK condyle prostheses prepared by FDM exhibited a uniform stress distribution and good mechanical properties, providing a theoretical basis for PEEK as a reconstruction material for repairing the temporomandibular joint.

Implicit and explicit finite element models predict the mechanical response of calcium phosphate-titanium cranial implants

The structural integrity of cranial implants is of great clinical importance, as they aim to provide cerebral protection after neurosurgery or trauma. With the increased use of patient-specific implants, the mechanical response of each implant cannot be characterized experimentally in a practical way. However, computational models provide an excellent possibility for efficiently predicting the mechanical response of patient-specific implants. This study developed finite element models (FEMs) of titanium-reinforced calcium phosphate (CaP-Ti) implants. The models were validated with previously obtained experimental data for two different CaP-Ti implant designs (D1 and D2), in which generically shaped implant specimens were loaded in compression at either quasi-static (1 mm/min) or impact (5 kg, 1.52 m/s) loading rates. The FEMs showed agreement with experimental data in the force-displacement response for both implant designs. The implicit FEMs predicted the peak load with an underestimation for D1 (9%) and an overestimation for D2 (11%). Furthermore, the shape of the force-displacement curves were well predicted. In the explicit FEMs, the first part of the force-displacement response showed 5% difference for D1 and 2% difference for D2, with respect to the experimentally derived peak loads. The explicit FEMs efficiently predicted the maximum displacements with 1% and 4% difference for D1 and D2, respectively. Compared to the CaP-Ti implant, an average parietal cranial bone FEM showed a stiffer response, greater energy absorption and less deformation under the same impact conditions. The framework developed for modelling the CaP-Ti implants has a potential for modelling CaP materials in other composite implants in future studies since it only used literature based input and matched boundary conditions. Furthermore, the developed FEMs make an important contribution to future evaluations of patient-specific CaP-Ti cranial implant designs in various loading scenarios.

Alloplastic Cranioplasty Reconstruction: A Systematic Review Comparing Outcomes With Titanium Mesh, Polymethyl Methacrylate, Polyether Ether Ketone, and Norian Implants in 3591 Adult Patients

BACKGROUND

Acquired defects of the cranium represent a reconstructive challenge in patients with calvarial bone loss due to trauma, infection, neoplasia, congenital malformations, or other etiologies. The objective of this study was to compare postoperative rates of infection, local complications, and allograft failures following cranioplasty reconstruction using titanium mesh (Ti), polymethyl methacrylate (PMMA), polyether ether ketone (PEEK), and Norian implants in adult patients.

METHODS

This constitutes the first systematic review of available literature on 4 different methods of alloplastic cranioplasty reconstruction, including Ti, PMMA, PEEK, and Norian implants, using the Newcastle-Ottawa Quality Assessment Scale guidelines for article identification, screening, eligibility, and inclusion. Electronic literature search included Ovid MEDLINE/PubMed, EMBASE, Scopus, Google Scholar, and Cochrane Database. Pearson exact test was utilized at P < 0.05 level of significance (J.M.P. v11 Statistical Software).

RESULTS

A total of 53 studies and 3591 patients (mean age, 40.1 years) were included (Ti = 1429, PMMA = 1459, PEEK = 221, Norian = 482). Polymethyl methacrylate implants were associated with a significantly higher infection rate (7.95%, P = 0.0266) compared with all other implant types (6.05%). Polyether ether ketone implants were associated with a significantly higher local complication rate (17.19%, P = 0.0307, compared with 12.23% in all others) and the highest ultimate graft failure rate (8.60%, P = 0.0450) compared with all other implant types (5.52%).

CONCLUSIONS

This study qualifies as a preliminary analysis addressing the knowledge gap in rates of infection, local surgical complication, and graft failure in alloplastic cranioplasty reconstruction with different implant types in the adult population. Longer-term randomized trials are warranted to validate associations found in this study.

Biofunctional Glycol-Modified Polyethylene Terephthalate and Thermoplastic Polyurethane Implants by Extrusion-Based Additive Manufacturing for Medical 3D Maxillofacial Defect Reconstruction

This work addresses the topic of extrusion-based additive manufacturing (filament-based material extrusion) of patient-specific biofunctional maxillofacial implants. The technical approach was chosen to overcome the shortcomings of medically established fabrication processes such as a limited availability of materials or long manufacturing times. The goal of the work was a successful fabrication of basic implants for defect reconstruction. The underlying vision is the implants' clinic-internal and operation-accompanying application. Following a literature search, a material selection was conducted. Digitally prepared three-dimensional (3D) models dealing with two representative mandible bone defects were printed based on the material selection. An ex-vivo model of the implant environment evaluated dimensional and fitting traits of the implants. Glycol-modified PET (PETG) and thermoplastic polyurethane (TPU) were finally selected. These plastics had high cell acceptance, good mechanical properties, and optimal printability. The subsequent fabrication process yielded two different implant strategies: the standard implant made of PETG with a build-up rate of approximately 10 g/h, and the biofunctional performance implant with a TPU shell and a PETG core with a build-up rate of approximately 4 g/h. The standard implant is meant to be intraoperatively applied, as the print time is below three hours even for larger skull defects. Standard implants proved to be well fitting, mechanically stable and cleanly printed. In addition, the hybrid implant showed particularly cell-friendly behavior due to the chemical constitution of the TPU shell and great impact stability because of the crack-absorbing TPU/PETG combination. This biofunctional constellation could be used in specific reconstructive patient cases and is suitable for pre-operative manufacturing based on radiological image scans of the defect. In summary, filament-based material extrusion has been identified as a suitable manufacturing method for personalized implants in the maxillofacial area. A further clinical and mechanical study is recommended.

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

Objective: Meta-analysis to evaluate complications in the use of autogenous bone and bone substitutes and to compare bone substitutes, specifically HA, polyetheretherketone (PEEK) and titanium materials.Methods: Search of PubMed, Cochrane, Embase and Google scholar to identify all citations from 2010 to 2019 reporting complications regarding materials used in cranioplasty.Results: 20 of 2266 articles met the inclusion criteria, including a total of 2913 patients. The odds of overall complication were significantly higher in the autogenous bone group (n = 214/644 procedures, 33.2%) than the bone substitute groups (n = 116/436 procedures, 26.7%, CI 1.29-2.35, p < 0.05). In bone substitutes groups, there was no significant difference in overall complication rate between HA and Ti (OR, 1.2; 95% CI, 0.47-3.14, p = 0.69). PEEK has lower overall complication rates (OR, 0.51; 95% CI, 0.30-0.87, p = 0.01) and lower implant exposure rates (OR, 0.17; 95% CI, 0.06-0.53, p = 0.002) than Ti, but there was no significant difference in infection rates and postoperative hematoma rates.Conclusions: Cranioplasty is associated with high overall complication rates with the use of autologous bone grafts compared with bone substitutes. PEEK has a relatively low overall complication rates in substitutes groups, but still high infection rates and postoperative hematoma rates. Thus, autologous bone grafts should only be used selectively, and prospective long-term studies are needed to further refine a better material in cranioplasty.

Craneoplastía con implante de polimetilmetacrilato (PMMA) para corregir secuela de trauma. Reporte de caso

Introducción: los defectos del cráneo y las anomalías del hueso craneofacial que requieren reconstrucción son comunes en una variedad de procedimientos neuroquirúrgicos. Después de una craniectomía o de fracturas craneofaciales posteriores a traumatismos cráneoencefálicos, los pacientes pueden desarrollar defectos cosméticos importantes. Algunos de estos son la depresión de la piel y un defecto de hundimiento que lleva a una apariencia asimétrica de la cabeza, sin dejar de lado las repercusiones físicas, neurológicas y psicológicas que estas lesiones conllevan. La reconstrucción craneofacial y la craneoplastía tienen una larga historia, pero las nuevas técnicas quirúrgicas y una multitud de opciones de materiales han impulsado recientemente el avance en esta área. Los implantes de polimetilmetacrilato (PMMA) han demostrado ser estables, biocompatibles, no conductores, radiotransparentes y de bajo costo. Es así que se pueden colocar y modificar fácilmente, con lo que se elimina la morbilidad del sitio donante. Presentación del caso: en este artículo presentamos un caso de craneoplastía de defecto frontal, posterior a traumatismo, cuya reconstrucción fue realizada mediante una prótesis de polimetilmetacrilato (PMMA) en el Hospital General Xoco de la Cuidad de México. Conclusión: se reporta la reducción del tiempo quirúrgico, además de un costo de la prótesis accesible para el paciente; de esta manera, se obtuvieron resultados satisfactorios y mejoras en el contorno estético facial, en tanto se permitió cobertura y protección para el tejido encefálico.La reconstrucción craneofacial y la craneoplastía tienen una larga historia, pero las nuevas técnicas quirúrgicas y una multitud de opciones de materiales han impulsado recientemente el avance en esta área.1 Los implantes de polimetilmetacrilato (PMMA) han demostrado ser estables, biocompatibles, no conductores, radiotransparentes y de bajo costo.6 Se pueden colocar y modificar fácilmente y se elimina la morbilidad del sitio donante. En este artículo presentamos un caso de craneoplastía de defecto frontal posterior a traumatismo realizada mediante una prótesis de polimetilmetacrilato (PMMA) en el Hospital General Xoco de la Cuidad de México, con la cual se logró reducir el tiempo quirúrgico, además el costo de la prótesis fue accesible para el paciente y se obtuvieron resultados satisfactorios.

Computer-Aided-Design/Computer-Aided-Manufacturing Titanium Cranioplasty in a Child: Critical Appraisal

Large skull bone defects of the cranial vault can result from various reasons. Reconstruction of these defects is performed for protective and aesthetic reasons but is also required for adequate intracranial homeostasis. Computer-aided-design/computer-aided-manufacturing (CAD/CAM) patient-specific skull implants have become the most valuable alternative to the traditional methods of reconstruction and a growing number of publications is dealing with this topic in adults. Literature related to the application of these implants in pediatric cranioplasty is, however, still scarce.The authors present a case of a 9-year-old boy, where cranioplasty using a CAD/CAM additive manufactured titanium implant led to improvement of symptoms attributed to cerebrospinal fluid circulation problems and intracranial homeostasis disbalance. The authors further reflect on what the role of cranioplasty should be in the therapeutic treatment plan.

Polymethylmethacrylate patient-matched implants (PMMA-PMI) for complex and revision cranioplasty: analysis of long-term complication rates and patient outcomes

Objective: Cranioplasty (CP) is associated with high complication rates and patient-matched implants (PMI) are frequently used for CP. However, only limited data are available regarding complication rates of PMI-based CP after complex or failed primary CP. Here we report our experience with the use of polymethylmethacrylate (PMMA) PMI for this purpose.Method: We analyzed all patients with complex or failed primary CP and subsequent implantation of PMMA-PMI between 2010 and 2015 at our institution.Results: A total of 67 patients (29 females, 38 males) with a mean age of 43 years (range: 13-74 years) were included in the study. Primary PMI-CP was performed in 18 patients with destructive or osteolytic bone tumors. Secondary PMI-CP was performed in 49 patients. Complications occurred in 14 patients with an overall complication rate of 21.7% during a mean follow-up of 39.7 ± 23.4 month. Approximately two-thirds of the patients reported a good quality of life after the initial event and subsequent CP. The majority of patients (>90%) was satisfied with the cosmetic result.Conclusion: Surgical CP with PMMA-PMI appears to be a suitable method for patients with failed or complex CP. Complication rates are comparable to those reported for primary CP.

The application of polyetheretherketone (PEEK) implants in cranioplasty

Cranioplasty is a challenge to neurosurgeons, especially considering protection of intracranial contents. In recent years, material choice for cranioplasty is still controversial, which brings complexity to this seemingly straightforward procedure. PEEK, a tough, rigid, biocompatible material, has been used more recently in cranioplasty to provide better protection. The aim of this review is to summarize the outcome of research conducted on the material for cranioplasty applications. We also reviewed the comparison of PEEK with several common materials in previous articles. This is also the most complete data review article at present. In addition, the combination of nano-materials and PEEK is also a hotspot of research, so we have made a careful review of this aspect. We also summarized our own experience, telling about the future prospects of PEEK in the field of clinical cranioplasty should be highlighted. Improving the bioactivity, porosity, thinning, biocompatibility, antibacterial ability, integration and cost reduction of PEEK implants without affecting their mechanical properties is a major challenge.

Cosmetic Outcome of Cranioplasty After Decompressive Craniectomy-An Overlooked Aspect

BACKGROUND

Cranioplasty (CP) is an obligatory surgery after decompressive craniectomy (DC). The primary objective is to protect the brain from external injury and prevent syndrome of trephined. In a government hospital, such cases pose a significant burden to a trauma center. Because of this reason, cosmetic outcome is never taken into account for the CP. We present results of CP performed at our hospital.

METHODS

This is a retrospective review of the cases of CP performed over the past 3 years at our hospital. The cosmetic outcome was divided into 3 grades: 1-good symmetrical, 2-irregularities, 2a-elevated and 2b depressed, and 3-bad cosmetic outcome requiring reoperation.

RESULTS

A total of 133 patients with acute brain injury underwent CP during the study period. The outcome was good in 74 (55.6%) and bad, requiring reoperation, in 2 (1.5%) cases. Various types of the CP materials like autologous bone flap, titanium mesh, and customized titanium plates were used. Methods of fixation were threads or miniplates and screws. In univariate analysis, cerebral venous thrombosis as an indication for DC, use of autologous bone flap, and fixation with thread were associated with poor outcome. However, in multivariate analysis only the method of implant fixation was associated with poor outcome. It was found that if screws and plates are used for fixation of bone flap, the chances of bad outcome are reduced by 74.6%.

CONCLUSIONS

The cosmetic outcome is overlooked for CP. The bone flap fixation has to be rigid for a good outcome.

A Large Calvarial Bone Defect in a Child: Osseointegration of an Implant

BACKGROUND

This original report describes the outcome of a cranioplasty at long-term follow-up. A large calvarial bone defect of a child was reconstructed with a bioactive and biostable nonmetallic implant.

CASE DESCRIPTION

In a child with infantile fibrosarcoma of occipital bone, the malignancy was removed at 2.5 years of age, and the defect site was reconstructed with an onlay glass fiber-reinforced composite-bioactive glass implant. The follow-up examination at 5 years 7 months showed no signs of tumor recurrence. During the follow-up period, the contour of the reconstructed area followed skull anatomic development. Computed tomography demonstrated considerably large areas (approximately 70% of the total area) of bone ongrowth to the peridural surface of the implant.

CONCLUSIONS

In the future, a synthetic cranioplasty material that is able to integrate with cranial bone may be considered superior to cryopreserved bone grafts in younger age groups.

Craniomaxillofacial patient-specific CAD/CAM implants based on cone-beam tomography data - A feasibility study

Customized implants have simplified surgical procedures and have improved patient outcome in craniomaxillofacial surgery. Traditionally, patient-specific data is gathered by conventional computed tomography (CT). However, cone-beam CT (CBCT) can generate a 3D reconstruction of the area of interest with a lower dose of radiation at reduced cost. In this study, we investigated the feasibility of using CBCT data to design and generate customized implants for patients requiring craniomaxillofacial reconstruction. We used CBCT to generate 62 implants for 51 consecutive patients admitted to our department between January 2015 and December 2017. The indications for reconstruction and types of reconstruction were very variable. In all cases, the implants were well fitted and no implant-related complications were detected. Pre-surgical planning was faster and more efficient as we did not have to consult a radiologist. Although CBCT data is more difficult to process than conventional CT data for the implant provider, the clinical advantages are pronounced and we now use CBCT as standard in our department. In conclusion, we have shown that using CBCT to design and manufacture customized implants for reconstruction of the craniomaxillofacial area is feasible and recommend this approach to other departments.

The effect of manufacturing techniques on custom-made titanium cranioplasty plates: A pilot study

OBJECTIVE

This study investigated the effect of varying techniques on the surface characteristics of pressed titanium cranioplasty plates, commonly manufactured in laboratory practice. The aim was to highlight the variety of techniques currently used, assess these methods of manufacture and produce manufacturing recommendations.

METHODS

A questionnaire identified manufacturing methods commonly used by maxillofacial prosthetists. The plate surfaces were examined using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) spectrometry. The surface differences and titanium compositions were statistically analysed.

RESULTS

Bead blasting with aluminium oxide (Al₂O₃) showed a significant decrease (p < 0.001) in titanium surface composition, replaced by a large aluminium content. Trimming tool choice had a significant impact (p = 0.001) on surface contamination by smoothing wheel material deposition; however passivation and anodising techniques had no significant effect (p = 0.293 and p = 0.257, respectively) on the surface composition or roughness of titanium samples.

CONCLUSIONS

A large range of manufacturing techniques of titanium cranioplasty plates was confirmed and significant differences were found. Amongst other recommendations, bead blasting with Al₂O₃ is not recommended for commercially pure titanium implant surface finishing due to aluminium contamination. The recommendations outlined will minimise manufacturing time, reduce risk of complication (thus costs) and unify methods to enable a safe, reliable treatment.