Custom made cranioplasty prostheses in porous hydroxy-apatite using 3D design techniques: 7 years experience in 25 patients

An innovative 3D hydroxyapatite patient-specific implant for maxillofacial bone reconstruction: A case series of 13 patients

The study aimed to evaluate and discuss the use of an innovative PSI made of porous hydroxyapatite, with interconnected porosity promoting osteointegration, called MyBone Custom® implant (MBCI), for maxillofacial bone reconstruction. A multicentric cohort of 13 patients underwent maxillofacial bone reconstruction surgery using MBCIs for various applications, from genioplasty to orbital floor reconstruction, including zygomatic and mandibular bone reconstruction, both for segmental defects and bone augmentation. The mean follow-up period was 9 months (1-22 months). No infections, displacements, or postoperative fractures were reported. Perioperative modifications of the MBCIs were possible when necessary. Additionally, surgeons reported significant time saved during surgery. For patients with postoperative CT scans, osteointegration signs were visible at the 6-month postoperative follow-up control, and continuous osteointegration was observed after 1 year. The advantages and disadvantages compared with current techniques used are discussed. MBCIs offer new bone reconstruction possibilities with long-term perspectives, while precluding the drawbacks of titanium and PEEK. The low level of postoperative complications associated with the high osteointegration potential of MBCIs paves the way to more extensive use of this new hydroxyapatite PSI in maxillofacial bone reconstruction.

Interest of a 3D custom-made implant in the reconstruction of bone defects of the cranial vault

The authors report a case of a patient managed for severe cranial vault depression following combined neurosurgery and radiotherapy. This situation caused major aesthetic discomfort and was potentially dangerous due to the mechanical weakness of the bone flap. The authors had a CAD (computer aided design) silicone elastomer custom-made implant made to fill perfectly the depression. Beforehand, an expansion was performed to cover the implant after removal of the radiated skin. The surgery and post-operative course raised no concerns. After one year of follow-up, the result is very good and the patient very satisfied, proving that this technique certainly has its place in the therapeutic arsenal when faced with a tissue defect of the cranial vault.

Custom-made 3D printing-based cranioplasty using a silicone mould and PMMA

All types of cranioplasty techniques restore the morphology of the skull and affect patient aesthetics. Safe and easy techniques are required to enhance patients' recovery and the rehabilitation process. We propose a new method of cranioplasty. The 3-dimensional (3D) reconstruction of a thin-layer computed tomography (CT) scan of the skull was used to reflect the intact side onto the defect and subtract the overlapping points from one another. In this way, a 3D model of the planned implant can be built in the required shape and size. The precise fit of the implant can be checked by printing the defective part of the skull in case it can be modified. A sterilisable silicone mould based on the finalized model was created afterwards. Polymethyl methacrylate implants were prepared directly in an aseptic environment in the operating room during surgery. Between 2005 and 2020, we performed 54 cranioplasties on 52 patients whose craniotomies were performed previously for indications of traumatic brain injury, stroke or tumour surgeries. No technical problems were noted during the operations. In 2 cases, septic complications that occurred were not connected to the technique itself, and the implants were removed and later replaced. Our proposed technique based on 3D-printed individual silicone moulds is a reliable, safe, easily reproducible and low-cost method to repair different skull defects.

Low-Cost 3-D-Printer-Assisted Personalized Cranioplasty Treatment: A Case Series of 14 Consecutive Patients

OBJECTIVE

The current study used polylactic acid molds [developed locally using three-dimensional printers and our software] and polymethyl methacrylate (PMMA) to perform cranioplasty of bone defects in technically demanding areas of the skull while ensuring ideal cosmetic results and functional recovery. The overall aim was to identify the ideal method for standard cranioplasty procedures METHODS: Polylactic acid duplicates of the skull defects were created for eligible patients, after which a two-part negative mold composed of plaster and silicone was used to form artificial bone with PMMA. Thereafter, cranioplasty was performed and the treatment success was assessed by evaluating the percentage of similarity objectively and the body image scale subjectively.

RESULTS

No surgical complications were seen to occur in the 14 patients included in the current study. Furthermore, the subjective and objective evaluation revealed a significant improvement in outcomes (p < 0.05). No postoperative complications were observed over a follow-up period of 6 months, except in 1 patient who exhibited late infection.

CONCLUSIONS

Cranioplasty operations were performed at an economical price of approximately US$50 dollars, suggesting that this method can be applied widely. Furthermore, preoperative preparation of the PMMA models can help reduce the duration of anesthesia and surgery which, in turn, will minimize the risk of surgical complications. Based on current knowledge in the field, we believe that this method represents the ideal technique.

A Multicentric European Clinical Study on Custom-Made Porous Hydroxyapatite Cranioplasty in a Pediatric Population

Background

Cranioplasty (CP) is a surgical intervention aiming to re-establish the integrity of skull defects. Autologous bone and different heterologous materials are used for this purpose, with various reported related complications, especially in children.This study aims to evaluate the rate of complication in a multicentric cohort of pediatric patients treated by porous hydroxyapatite (PHA) CP implantation and to assess the reliability of post-marketing clinical data collected by a manufacturing company.

Methods

The authors proactively collected clinical data from 20 institutions in different European countries for patients under the age of 16 treated with a PHA implant. The data were obtained by conducting an on-site interview with physicians in charge of the patients (Post-Marketing Surveillance, PMS group). The endpoints were the incidence of adverse events and related implant removal. The clinical data were compared to the company-based register including all patients under the age of 16 who received the same implant from January 1, 2004 to December 31, 2020, and the collecting complications voluntarily reported by surgeons (Database, DB group).

Results

The two groups were similar in terms of demographic characteristics and rate of complications. In the PMS group, a total of 11 (16.9%) complications were reported in the group of 65 patients that were proactively collected. Both fractures and infections were the most common complications with 4 cases each (6.2%). In the case of both infections and fractures, revision surgery was required for only one patient (1.5%). Three (4.5%) cases of displacements were reported, and in one (1.5%) case, a surgical revision was required, for a total of 3 (4.5%) cases requiring surgical revision. The average follow-up was 26.7 months.

Conclusions

Different from a previous study on adult age, pediatric neurosurgeons are more prone to report even to the manufacturing company complications related to skull reconstruction in children. Therefore, these data can be compared with those of other clinical studies. The PHA CP in this series of 65 patients presents a complication rate collected on-site that is similar to other heterologous materials.

Characterisation of Selected Materials in Medical Applications

Tissue engineering is an interdisciplinary field of science that has developed very intensively in recent years. The first part of this review describes materials with medical and dental applications from the following groups: metals, polymers, ceramics, and composites. Both positive and negative sides of their application are presented from the point of view of medical application and mechanical properties. A variety of techniques for the manufacture of biomedical components are presented in this review. The main focus of this work is on additive manufacturing and 3D printing, as these modern techniques have been evaluated to be the best methods for the manufacture of medical and dental devices. The second part presents devices for skull bone reconstruction. The materials from which they are made and the possibilities offered by 3D printing in this field are also described. The last part concerns dental transitional implants (scaffolds) for guided bone regeneration, focusing on polylactide-hydroxyapatite nanocomposite due to its unique properties. This section summarises the current knowledge of scaffolds, focusing on the material, mechanical and biological requirements, the effects of these devices on the human body, and their great potential for applications.

Three dimensional custom-made PEEK cranioplasty

BACKGROUND

An optimal reconstruction of calvarial skull defects is a challenge for neurosurgeons, and the strategy used to achieve the best result remains debatable. Therefore, we conducted this study to compare the esthetic and functional outcome of custom-made three-dimensional (3D) cranioprostheses to handmade bone cement in reconstructing calvarial skull defects.

METHODS

We included 66 patients above 10 years of age with calvarial skull defects and undergoing reconstruction: 33 were enrolled in the custom-made 3D implants group and 33 in the handmade implants group in the period from August 2017 to December 2020 in the neurosurgery department of Fayoum University Hospital.

RESULTS

Complete success of the esthetic end-point was insignificantly higher in the custom-made 3D prostheses group based on the doctor's and patients' assessment (60.6% vs. 42.4%; 33.3% vs. 9.1%, P > 0.05), respectively. Complete success of the functional end-point was significantly higher in the custom-made 3D group compared to the handmade cement bone group according to the doctor's and patients' assessment (60.6% vs. 0%; 21.2% vs. 0%, P < 0.05). There were no late complications noted in the custom-made 3D prosthesis group, whereas 50% of the handmade bone group had late complications (P < 0.05). Full improvement of the symptoms of the "syndrome of trephined" was achieved in the 3D custom-made group compared to the handmade bone cement group (20% vs. 0%).

CONCLUSION

Cranioplasty using three dimensional customs made PEEK prosthesis is a reliable method which saves operative time, lowers cost and provides less complications if compared with other cranioplasty techniques. Custom-made 3D cranioprostheses are better than handmade bone cement in reconstructing calvarial defects in terms of esthetic and functional outcome as well as complications.

Using Cranial Sutures in a Single-Step Frame-Guided Resection and Reconstruction for Intraosseous Meningiomas: Technical Note

BACKGROUND

Single-stage surgical treatment of cranial intraosseous meningiomas includes complete tumor resection followed by aesthetic reconstruction. Tailored tumor resection with a computer-aided design/computer-aided manufacturing custom-made implant for the defect has been advocated in recent years to achieve a satisfactory cosmetic result with reduced operative time and fewer complications. However, several technical nuances related to the area of osseous removal may compromise cranioplasty.

METHODS

We present 2 cases of intraosseous meningiomas (sphenoid wing and retromastoid) to illustrate a step-by-step approach, from preoperative planning to single-step surgery.

RESULTS

For each case, a customized frame template delimiting bone removal was designed using cranial sutures as anatomical landmarks for precise placement of the cranioplasty template over the area of interest.

CONCLUSIONS

Custom templates based in cranial sutures may benefit single-step frame-guided resection and reconstruction of intraosseous tumors with compelling results.

AK, Faujdar DS. Bony Union and Flap Resorption in Cranioplasty with Autologous Subcutaneous Pocket Preserved Bone Flap: Early Report on an Ambidirectional CT Scan-Based Study

Introduction Absence of sufficient number of prospective randomized controlled studies and comparatively small sample size and short follow-up period of most of the studies, available so far, have left ambiguity and lack of standardization of different aspects of cranioplasty.

Materials and Methods This is an early report of a computed tomography scan image-based ambidirectional study on cranioplasties performed with autologous subcutaneous pocket preserved bone flaps. Retrospective arm compared bony union and factors influencing it between cranioplasties and craniotomies. Patients with poor bony union and aseptic resorption were followed up in the prospective arm.

Results Retrospective arm of the study, followed up for five years (mean 32.2 months), comprised 42 patients as cases (Group 1) and 29 as controls (Group 2). Twenty-seven individuals (64.3%) in Group 1 had good bony union, as compared with 20 (68.9%) good unions in Group 2 out of the 29 patients. Four patients (9.5%) in Group 1 showed evidence of flap resorption, a finding absent in any patient in Group 2. Age, sex, smoking habits, superficial skin infection, and method of fixation did not appear to have any implication on bony union. Craniotomies done using Gigli saws fared better as compared with those done with pneumatic saw with lesser flap size–craniectomy size discrepancy, though it was not statistically significant. Fifteen patients have been included in the Prospective arm at the time of submission of this article.

Conclusion Ours is a study with a small sample size, unable to put its weight on any side, but can surely add some more data to help the Neurosurgeons in choosing the best for their patients.

Cranioplasty with three-dimensional customised mould for polymethylmethacrylate implant: a series of 16 consecutive patients with cost-effectiveness consideration

Background

Different methods of cranioplasty for the reconstruction of bony skull defects exist. In the absence of the autologous bone flap, a customised manufactured implant may be the optimal choice, but this implant has several limitations regarding its technical standardisation and better cost-effectiveness.

Methods

This study presents a series of 16 consecutive patients who had undergone cranioplasty with customised three-dimensional (3D) template moulds for polymethylmethacrylate (PMMA) implants manufactured after 3D modelling on a specific workstation. The virtual images were transformed into a two-piece physical model using a 3D printer for the biomaterials. PMMA implant was produced intraoperatively with the custom mould. Cosmetic results were analysed by comparing pre- and postoperative 3D computed tomography (CT) images and asking if the patient was satisfied with the result.

Results

The average total time for planning and production of customised mould was 10 days. The 16 patients were satisfied with the result, and CT images presented harmonious symmetry when comparing pre- and postoperative scans. Cases of postoperative infection, bleeding, or reoperation in this series were not observed.

Conclusion

Cranioplasty with high-technology customised 3D moulds for PMMA implants can allow for an aesthetic reconstruction with a fast and cost-effective manufacturing process and possibly with low complication rates.

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.

Long-term follow-up of custom-made porous hydroxyapatite cranioplasty in adult patients: a multicenter European study. Can we trust self-reported complications?

BACKGROUND

Cranioplasty is a surgical intervention aiming to re-establish the integrity of skull defects. Autologous bone and different heterologous materials are used for this purpose, with various reported related complications. The aim of the study was to evaluate the complication rate in a multicentric cohort of patients underwent porous hydroxyapatite (PHA) cranioplasty implantation and to assess the validity of company post-market clinical analysis.

METHODS

Authors analyzed a company based register of 6279 PHA cranioplasty implanted all over the world. In these adult patients only self-reported complications were available. We then obtained the data of adult patients treated with custom-made porous HA prostheses (CustomBone Service) in 20 institutions from different European countries through an on-site interview with the physicians in charge of the patients (494 patients). The endpoints were the incidence of adverse events and of related implant removal.

RESULTS

The groups of patients had similar demographics characteristics. The average follow-up was 26.7 months. A significantly higher number of complications was recorded in the group of patients underwent onsite interview. Thirty-nine complications were reported (7.89%) with an explantation rate of 4.25% (21 cases) in the series, compared to the data reported from the Company (complications rate of 3.3% and explantation rate of 3.1%). The most common complications were infection (4.86%), hematomas (1.22%), fractures (1.01%), mobilization (0.4%) and scar retraction (0.4%).

CONCLUSIONS

Our data confirm that porous HA cranioplasty is at least as effective as other heterologous materials to repair cranial defects. Another interesting finding is that self-reporting complicantions by surgeons does not give a precise picture of the real rate of complications of the devices. These data in future studies need to be re-confirmed with on-site interviews.

Three-Dimensional CAD in Skull Reconstruction: A Narrative Review with Focus on Cranioplasty and Its Potential Relevance to Brain Sciences

In patients suffering from severe traumatic brain injury and massive stroke (hemorrhagic or ischemic), decompressive craniectomy (DC) is a surgical strategy used to reduce intracranial pressure, and to prevent brainstem compromise from subsequent brain edema. In surviving patients, cranioplasty surgery helps to protect brain tissue, and correct the external deformity. The aesthetic outcome of cranioplasty using an asymmetrical implant can negatively influence patients physically and mentally, especially young patients. Advancements in the development of biomaterials have now made three-dimensional (3-D) computer-assisted design/manufacturing (CAD/CAM)-fabricated implants an optimal choice for the repair of skull defects following DC. Here, we summarize the various materials for cranioplasty, including xenogeneic, autogenous, and alloplastic grafts. The processing procedures of the CAD/CAM technique are briefly outlined, and reflected our experiences to reconstruct skull CAD models using commercial software, published previously, to assess aesthetic outcomes of regular 3-D CAD models without contouring elevation or depression. The establishment of a 3-D CAD model ensures a possibility for better aesthetic outcomes of CAM-derived alloplastic implants. Finally, clinical consideration of the CAD algorithms for adjusting contours and their potential application in prospective healthcare are briefly outlined.

Three-Dimensional CAD in Skull Reconstruction: A Narrative Review with Focus on Cranioplasty and Its Potential Relevance to Brain Sciences

In patients suffering from severe traumatic brain injury and massive stroke (hemorrhagic or ischemic), decompressive craniectomy (DC) is a surgical strategy used to reduce intracranial pressure, and to prevent brainstem compromise from subsequent brain edema. In surviving patients, cranioplasty surgery helps to protect brain tissue, and correct the external deformity. The aesthetic outcome of cranioplasty using an asymmetrical implant can negatively influence patients physically and mentally, especially young patients. Advancements in the development of biomaterials have now made three-dimensional (3-D) computer-assisted design/manufacturing (CAD/CAM)-fabricated implants an optimal choice for the repair of skull defects following DC. Here, we summarize the various materials for cranioplasty, including xenogeneic, autogenous, and alloplastic grafts. The processing procedures of the CAD/CAM technique are briefly outlined, and reflected our experiences to reconstruct skull CAD models using commercial software, published previously, to assess aesthetic outcomes of regular 3-D CAD models without contouring elevation or depression. The establishment of a 3-D CAD model ensures a possibility for better aesthetic outcomes of CAM-derived alloplastic implants. Finally, clinical consideration of the CAD algorithms for adjusting contours and their potential application in prospective healthcare are briefly outlined.

Hydroxyapatite ceramic implants for cranioplasty in children: a retrospective evaluation of clinical outcome and osteointegration

INTRODUCTION

Cranioplasty in children is a controversial and challenging issue, since there is still no consensus on the ideal material. Main problems in paediatric age are represented by the child's growing skull, the lower bone thickness and the high incidence of cerebrospinal fluid (CSF) disorders or brain swelling. Autologous bone is still considered the "gold standard". When it is not available, a wide range of alloplastic materials have been proposed. Hydroxyapatite, a ceramic-based derivative, bears a chemical composition very similar to the human natural bone, making this material a valuable alternative to other cranioplasty solutions.

METHODS

All patients implanted with a custom-made porous hydroxyapatite device at Santobono-Pausilipon Hospital in Naples were retrospectively reviewed. A follow-up CT scan of the skull was performed from 1 up to 48 months postoperatively to document the bone ingrowth as well as the osteointegration process. The bone density was measured as according to the Hounsfield scale at the bone-implant interface.

RESULTS

Between 2014 and 2018, 11 patients (7 males, 4 females) underwent cranioplasty with hydroxyapatite ceramic implants (HAP). Patients' age ranged between 3 and 16 years old. Initial aetiology was trauma in most cases. Two subjects were implanted with HAP as primary cranioplasty, 9 as revision surgery following previous cranioplasty failure. Sites of the cranial defect were unilateral fronto-temporo-parietal (N = 8), unilateral frontal (N = 1) and bifrontal (N = 2). Two patients with large bilateral defects received two prostheses. In one of these, the two prostheses were explanted and replaced with two back-up implants (accounting for a total of 15 implants in 11 patients). Osteointegration was measurable for 12 out of 15 implanted devices. The mean percentage was about 51%. There were six asymptomatic prosthesis fractures (40%), all occurring within 6 months from implant. In one case, the bifrontal prostheses were explanted and replaced. This was the only patient who underwent revision surgery.

CONCLUSION

Hydroxyapatite ceramic implants represent a valid alternative to other cranioplasty solutions. Where coaptation occurs correctly, with good osteointegration, implant mechanical resistance increases over time.

Custom-made Hydroxyapatite Cranioplasty: Radiological and Histological Evidence of Bone-Biomaterial Osteointegration in Five Patients

Custom-made cranial implants facilitate the surgical reconstruction of destructive pathologies of the skull or extensive demolitive skull surgery. Customized cranioplasty allows for an immediate restoration of the functional integrity of the cranial defect (restitutio ad integrum), with excellent functional and esthetic outcome and a quick, safe, and simple procedure. In this context, bioceramics like hydroxyapatite (HA) claim high biocompatibility and bone-binding capability. The osteoconductive properties of the HA have been reported in animal models and humans. The purpose of this study is to demonstrate with radiological and histological examination and how HA prosthesis may integrate after their implantation showing data related to five patients that needed primary HA cranial reconstruction with secondary removal after few years. The histological examination showed neo-formed lamellar/trabecular bone tissue fragments accompanied by the amorphous reticular tissue (HA prosthesis) revealing diffuse ossification sites in all included cases.

Demineralized Bone Matrix and Resorbable Mesh Bilaminate Cranioplasty Is Ineffective for Secondary Reconstruction of Large Pediatric Cranial Defects

Replacement of the autologous bone flap after decompressive craniectomy can be complicated by significant osteolysis or infection with large defects over scarred dura. Demineralized bone matrix is an alternative to autologous reconstruction, effective when reconstructing large defects using a resorbable mesh bilaminate technique in primary cranioplasty, but this technique has not been studied for revision cranioplasty and the setting of scarred dura. Retrospective review was performed of patients receiving demineralized bone matrix and resorbable mesh bilaminate cranioplasty for postdecompressive craniectomy defects. Seven patients (mean age, 4.2 years) were identified with a mean follow-up of 4.0 years. Computed tomography before the demineralized bone matrix and resorbable mesh bilaminate cranioplasty and at least 1 year postoperatively were compared. Defects were characterized and need for revision was assessed. All patients had craniectomy with associated hemidural scarring. Five patients had autologous bone flap cranioplasty associated with nearly total osteolysis, and two patients had deferral of bone flap before demineralized bone matrix and resorbable mesh bilaminate cranioplasty. Demineralized bone matrix and resorbable mesh bilaminate cranioplasty demonstrated unpredictable and poor ossification, with bony coverage unchanged at postoperative follow-up. All patients required major revision cranioplasty at a mean time of 2.5 years. Porous polyethylene was successfully used in six of the revisions, whereas exchange cranioplasty was used in the remaining patient, with a mean follow-up of 1.4 years. Although demineralized bone matrix and resorbable mesh bilaminate is appropriate for primary cranioplasty, it should be avoided in the setting of scarred or infected dura in favor of synthetic materials or exchange cranioplasty. CLINICAL QUESTION/LEVEL OF EVIDENCE:: Therapeutic, IV.

Comparison between the different types of heterologous materials used in cranioplasty: a systematic review of the literature

INTRODUCTION

The choice of heterologous materials for cranioplasty after decompressive craniectomy is still difficult. The aim of this study is to examine the association between material of choice and related complications to suggest the best treatment option.

EVIDENCE ACQUISITION

A systematic review was performed for articles reporting cranioplasty comparing the following heterologous implants: titanium, poli-methyl-methacrylate (PMMA), polyetheretherketone (PEEK) and hydroxyapatite (HA). Extracted data included implant materials and incidence of the most frequent complications.

EVIDENCE SYNTHESIS

The final selection resulted in 106 papers but according to our rules only 27 studies were included in the final analysis. Among a total of 1688 custom-made prosthesis implanted, 649 were titanium (38.49%), 298 PMMA (17.56%), 233 PEEK (13.82%), and 508 were HA (30.13%). A total of 348 complications were recorded out of 1688 reported patients (20.64%). In the titanium group, 139 complications were recorded (21.42%); in the PMMA group 57 (19.26%), in the PEEK group 49 (21.03%) and in the HA group 103 (20.3%). If we examine a summary of the reported complications clearly related to cranioplasty (postoperative infections, fractures and prosthesis displacement) versus type of material in multicentric and prospective studies we can see how HA group patients have less reported infections and cranioplasty explantation after infections than PMMA, PEEK and titanium. On the contrary HA patients seem to have a higher number of prosthesis displacement again if compared with the other materials. Since these data are not derived from a statistically correct analysis they should be used only to help to differentiate the properties of the various heterologous cranioplasties.

CONCLUSIONS

The ideal material for all heterologous cranioplasty has not yet been identified. The choice of material should be based on the clinical data of patients, such as the craniectomy size, presence of seizures, possibility of recovery, good long-term outcome associated with a cost analysis.

An investigation of factors associated with the development of postoperative bone flap infection following decompressive craniectomy and subsequent cranioplasty

OBJECTIVE

After a decompressive craniectomy (DC), a cranioplasty (CP) is often performed in order to improve neurosurgical outcome and cerebral blood circulation. But even though the performance of a CP subsequent to a DC has become routine medical practice, patients can in fact develop many complications from the surgery that could prolong hospitalization and lead to unfavorable prognoses. This study investigates one of the most frequent complications, bone flap infection, in order to identify prognostic factors of its development.

PATIENTS AND METHODS

In this single-center study, we have retrospectively examined 329 CPs performed between 2002 and 2017. Multiple categorical and metric parameters (e.g., timing of CP, bone flap material, specific laboratory signs of infection and reason for DC) were analyzed applying unadjusted and multivariable testing.

RESULTS

Bone flap infection occurred in 24 patients (7.3%). A CP performed more than six months after a DC is associated with a significantly increased risk of infection (OR = 0.308 [0.118; 0.803], p = 0.016). However, with CPs performed after twelve months, the incidence decreases, but without provable statistical impact. In addition, bone flap infection is strongly related to the neurological outcome and the material used for the skull implant, with the use of synthetic bone flaps leading to a marked increase in the rate of infection (p < 0.001).

CONCLUSIONS

This study supports the hypothesis that the risk of infection is higher the longer the elapsed time between DC and CP, especially if more than six months. Based on our results, the best DC-CP time frame for keeping the infection rate low is performing the CP within the first six months after the DC. In the event that the CP cannot be performed within the first six months, a CP performed twelve months or more after the DC seems to have a favorable outcome as well.

Removal of giant intraosseous meningioma followed by cranioplasty using a custom-made bioceramic implant: case report

Intraosseous meningioma of the chordoid type is a rare clinical entity. Radical surgical removal and subsequent cranioplasty is the treatment of choice. Here, the authors report a severe case involving more than 70% of the calvarial surface area, which was removed and repaired using a prefabricated custom-made, titanium-reinforced, bioceramic implant and bone-cutting guides. Tumor removal and good esthetic outcome were achieved, along with a 17.1% increase of intracranial volume. Bioceramic implants have shown promising initial results and may represent an important new tool in the surgeon's armamentarium.

Evaluation of neurosurgical implant infection rates and associated pathogens: evidence from 1118 postoperative infections

OBJECTIVE

Various implanted materials are used in neurosurgery; however, there remains a lack of pooled data on infection rates (IRs) and infective bacteria over past decades. The goal of this study was to investigate implant infections in neurosurgical procedures in a longitudinal retrospective study and to evaluate the IRs of neurosurgically implanted materials and the distribution of pathogenic microorganisms.

METHODS

A systematic literature search was conducted using PubMed and Web of Science databases for the time period between 1968 and 2018. Neurosurgical implant infections were studied in 5 subgroups, including operations or diseases, implanted materials, bacteria, distribution by country, and time periods, which were obtained from the literature and statistically analyzed. In this meta-analysis, statistical heterogeneity across studies was tested by using p values and I2 values between studies of associated pathogens. Egger’s test was used for assessing symmetries of funnel plots with Stata 11.0 software. Methodological quality was assessed to judge the risk of bias according to the Cochrane Handbook.

RESULTS

A total of 22,971 patients from 227 articles satisfied the study’s eligibility criteria. Of these, 1118 cases of infection were reported, and the overall IR was 4.87%. In this study, the neurosurgical procedures or disorders with the top 3 IRs included craniotomy (IR 6.58%), cranioplasty (IR 5.89%), and motor movement disorders (IR 5.43%). Among 13 implanted materials, the implants with the top 3 IRs included polypropylene-polyester, titanium, and polyetheretherketone (PEEK), which were 8.11%, 8.15%, and 7.31%, respectively. Furthermore, the main causative pathogen was Staphylococcus aureus and the countries with the top 3 IRs were Denmark (IR 11.90%), Korea (IR 10.98%), and Mexico (IR 9.26%). Except for the low IR from 1998 to 2007, the overall implant IR after neurosurgical procedures was on the rise.

CONCLUSIONS

In this study, the main pathogen in neurosurgery was S. aureus, which can provide a certain reference for the clinic. In addition, the IRs of polypropylene-polyester, titanium, and PEEK were higher than other materials, which means that more attention should be paid to them. In short, the total IR was high in neurosurgical implants and should be taken seriously.

Two-Staged Frontal Bone Defect Reconstruction: Perioperative Assessment of Scalp Vascularization Using Near-Infrared Indocyanine Green Video Angiography (Visionsense Iridium)

BACKGROUND

Head trauma and neurosurgical-related osteomyelitis are common causes of cranial bone defect. Even though cranioplasty is considered a safe and well-consolidated procedure, there are still some issues about the flap's vascularization assessment. In this paper we describe a 2-staged cranioplasty procedure, focusing on the perioperative evaluation of the skin flap vascularization. Our goal is to assess if the skin flap's perfusion measurement with indocyanine green fluorescence can be considered a reliable method to predict good outcome in cranioplasties.

CASE DESCRIPTION

A 50-year-old patient presented with a wide frontal bone defect due to a prior surgery-related osteomyelitis. During the first operation, a tissue expander was placed under the scalp in order to grant an appropriate skin stretching. During the second operation the defect was repaired with a custom-made prosthesis after tissue expander removal. During all procedures, vascular integrity of the skin flap was intraoperatively assessed by means of indocyanine green fluorescence.

CONCLUSIONS

Surgical procedures were well tolerated; at 1 year of follow-up the cosmetic defect was unremarkable. Indocyanine green fluorescence can be a good aid to predict the probability of the skin flap survival by measuring its perfusion.

Incidence and Risk Factors for Skull Implant Displacement After Cranial Surgery

OBJECTIVE

Various complications that can occur during and after cranial surgery have been investigated extensively. One of the less frequent complications has thus far received little attention, however: displacement of the skull implant after craniotomy or craniectomy. The purpose of this study is to identify prognostic factors for the development of skull implant displacement (SID).

METHODS

In this study, 9087 cranial surgeries performed between 2002 and 2017 were retrospectively examined for the occurrence of SID. Because a first analysis of the investigated data revealed that a notable number of SIDs occurred after a cranioplasty (CP) performed after a decompressive craniectomy (DC), we focused our investigation on these cases. A total of 669 DCs and 329 subsequently performed CPs were analyzed. Several factors were analyzed unadjusted as possible factors influencing the risk for the development of SID.

RESULTS

A total of 13 implant dislocations occurred after CP (3.95%). Fixation technique is the only factor that seems to have had a significant influence, specifically not using miniplates as the fixation technique, which was associated with a higher risk of SID (P = 0.043). However, if fixation techniques are distinguished in more detail, no significant advantage of the miniplates over titanium clamps can be proven (P = 0.123). None of the remaining observed factors showed a statistically provable impact in our data.

CONCLUSIONS

A notable number of SIDs only occur after CPs that follow a DC. An advantage in successful placement was observed when fixation of the skull implant during cranioplasty was performed using miniplates.

Hydroxyapatite cranioplasty: a retrospective evaluation of osteointegration in 17 cases

BACKGROUND

Cranial reconstruction with autologous bone is still the gold standard although several biomaterials are available to re-establish the integrity of the cranial vault. Due to their biological and morphological characteristics, hydroxyapatite implants show promising results in small clinical cohort studies, especially within the paediatric population. Its biocompatibility and osteoconductivity should allow the formation of osseous bridging at the skull-prosthesis interface.

OBJECTIVE

To examine the possible occurrence of osteointegration and to quantify it.

METHODS

A retrospective study of patients with a hydroxyapatite implant from 2010 to 2014 at our neurosurgical department was conducted. Demographic, surgical and radiological data were studied. A senior neuroradiologist, a staff member neurosurgeon and a resident neurosurgeon independently performed the radiological evaluation. A new software analysis technique was developed to objectively quantify the degree of osteointegration.

RESULTS

Seventeen implants were evaluated with an average patient age of 39 years and a mean follow-up of 155 weeks. Through radiologic evaluation, osseous bridging was deemed higher than 50% in six prostheses and higher than 75% in three. In five patients, no osteointegration could be seen. The remaining patients exhibited sparse signs of osteointegration, estimated between 10 and 50%. Software analysis showed an average osteointegration ratio of 37.4% with a 400-HU filter and 27.3% with a 700-HU filter.

CONCLUSION

In this small retrospective study of cranial hydroxyapatite implants, osteointegration did occur and to a degree of more than 50% in 1/3 of the patients.

Cranial autologous bone flap resorption after a cranioplasty: A case report

BACKGROUND

Craniectomies and cranioplasty are common neurosurgical procedures performed after brain trauma, ischemia, tumor resection, or infection. Post-cranioplasty autologous bone flap resorption may occur in patients after delayed cranial reconstruction. The occurrence is usually low when bone flaps are stored in subcutaneous abdominal tissue. We report a unique case of post-cranioplasty cranial bone flap.

CASE DESCRIPTION

We report a total autologous bone flap resorption in a 28-year-old man with a history of alcohol abuse. He was found unconscious in his bedroom with a head trauma of unknown mechanism. After an emergency room assessment, he was diagnosed with an acute subdural hematoma and underwent to emergency surgical drainage and a craniectomy. Three months later, a cranioplasty was performed and he exhibited exceptional outcomes. During a follow-up assessment, 7 months post-cranioplasty, total bone flap resorption was observed on computerized tomography image.

CONCLUSION

This case described an abnormal accelerated resorption of an autologous bone flap cranioplasty inserted after 3 months. Thus, to avoid bone flap resorption, an as early as possibly strategy may prevent this. Still, the exact mechanisms underlying bone resorption are poorly understood.

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.

Removal of a Frontal Sinus Osteoma and Reconstruction by a Custom-Made Implant with Neuronavigation Assistance

The authors report the surgical treatment of an extensive right frontal sinus osteoma assisted by neuronavigation and reconstruction by a hydroxyapatite custom-made implant. The patient presents with ptosis, hypoglobus, and proptosis of the right eye, without any visual impairment. Computed tomographic (CT) scan showed a very large bony mass involving right frontal sinus and displacing the orbital roof. A stereolithographic model-guided planning was carried out to obtain a practical simulation of the surgical operation and it was submitted to a new CT scan to acquire the reference point to realize the neuronavigation assistance, and to achieve the template to realize the hydroxyapatite custom-made implant. Intraoperatively, with the help of neuronavigation assistance, osteotomies were performed by piezoelectric device. The reconstruction was made using a hydroxyapatite custom-made implant. The procedure was damage free, the bony mass was excised, and the orbital roof was repaired without any adverse effects. Postsurgical CT scan and scintigraphy showed a good reconstruction and a good-quality osteoblasts activity on the borders of the implant. Osteoma is a benign slow-growing bone tumor, usually involving the frontal sinus. Navigational assistance offers a very important help to perform safe osteotomies. Hydroxyapatite custom-made implant seems to be an excellent reconstructive method.

Timing of cranioplasty: a 10.75-year single-center analysis of 754 patients

OBJECTIVE Despite their technical simplicity, cranioplasty procedures carry high reported morbidity rates. The authors here present the largest study to date on complications after cranioplasty, focusing specifically on the relationship between complications and timing of the operation. METHODS The authors retrospectively reviewed all cranioplasty cases performed at Harborview Medical Center over the past 10.75 years. In addition to relevant clinical and demographic characteristics, patient morbidity and mortality data were abstracted from the electronic medical record. Cox proportional-hazards models were used to analyze variables potentially associated with the risk of infection, hydrocephalus, seizure, hematoma, and bone flap resorption. RESULTS Over the course of 10.75 years, 754 cranioplasties were performed at a single institution. Sixty percent of the patients who underwent these cranioplasties were male, and the median follow-up overall was 233 days. The 30-day mortality rate was 0.26% (2 cases, both due to postoperative epidural hematoma). Overall, 24.6% percent of the patients experienced at least 1 complication including infection necessitating explantation of the flap (6.6%), postoperative hydrocephalus requiring a shunt (9.0%), resorption of the flap requiring synthetic cranioplasty (6.3%), seizure (4.1%), postoperative hematoma requiring evacuation (2.3%), and other (1.6%). The rate of infection was significantly higher if the cranioplasty had been performed < 14 days after the initial craniectomy (p = 0.007, Holm-Bonferroni-adjusted p = 0.028). Hydrocephalus was significantly correlated with time to cranioplasty (OR 0.92 per 10-day increase, p < 0.001) and was most common in patients whose cranioplasty had been performed < 90 days after initial craniectomy. New-onset seizure, however, only occurred in patients who had undergone their cranioplasty > 90 days after initial craniectomy. Bone flap resorption was the least likely complication for patients whose cranioplasty had been performed between 15 and 30 days after initial craniectomy. Resorption was also correlated with patient age, with a hazard ratio of 0.67 per increase of 10 years of age (p = 0.001). CONCLUSIONS Cranioplasty performed between 15 and 30 days after initial craniectomy may minimize infection, seizure, and bone flap resorption, whereas waiting > 90 days may minimize hydrocephalus but may increase the risk of seizure.

Autogenous Bone Reconstruction of Large Secondary Skull Defects

BACKGROUND

The authors sought to ascertain the upper limits of secondary skull defect size amenable to autogenous reconstructions and to examine outcomes of a surgical series. Published data for autogenous and alloplastic skull reconstructions were also examined to explore associations that might guide treatment.

METHODS

A retrospective review of autogenously reconstructed secondary skull defects was undertaken. A structured literature review was also performed to assess potential differences in reported outcomes between autogenous bone and synthetic alloplastic skull reconstructions. Weighted risks were calculated for statistical testing.

RESULTS

Ninety-six patients underwent autogenous skull reconstruction for an average defect size of 93 cm (range, 4 to 506 cm) at a mean age of 12.9 years. The mean operative time was 3.4 hours, 2 percent required allogeneic blood transfusions, and the average length of stay was less than 3 days. The mean length of follow-up was 28 months. There were no postoperative infections requiring surgery, but one patient underwent secondary grafting for partial bone resorption. An analysis of 34 studies revealed that complications, infections, and reoperations were more commonly reported with alloplastic than with autogenous reconstructions (relative risk, 1.57, 4.8, and 1.48, respectively).

CONCLUSIONS

Autogenous reconstructions are feasible, with minimal associated morbidity, for patients with skull defect sizes as large as 500 cm. A structured literature review suggests that autogenous bone reconstructions are associated with lower reported infection, complication, and reoperation rates compared with synthetic alloplasts. Based on these findings, surgeons might consider using autogenous reconstructions even for larger skull defects.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Bone Regenerative Medicine in Oral and Maxillofacial Region Using a Three-Dimensional Printer<sup/>

Bone grafts currently used for the treatment of large bone defect or asymmetry in oral and maxillofacial region include autologous, allogeneic, and artificial bones. Although artificial bone is free from the concerns of donor site morbidity, limitation of volume, disease transmission, and ethical issues, it lacks osteogenic and osteoinductive activities. In addition, molding of the artificial bone is an issue especially when it is used for the augmentation of bone as onlay grafts. To solve this problem, additive manufacturing techniques have been applied to fabricate bones which have outer shapes conformed to patients' bones. We developed a custom-made artificial bone called a computed tomography (CT)-bone. Efficacy of CT-bone was proven in a clinical research and clinical trial, showing good manipulability, stability, and patient satisfaction. However, low replacement rate of artificial bones by endogenous bones remain an unsolved issue. Loading of cells and growth factors will improve the bone replacement by inducing osteogenic and osteoinductive activities. In addition, the three-dimensional bioprinting technique will facilitate bone regeneration by placing cells and biological substances into appropriate sites.

Cranial Reconstruction Using Autologous Bone and Methylmethacrilate

BACKGROUND

Having in mind the importance of reconstruction of the calvaria, our goal was to compare the complication rates following the use of autologous bone and methylmethacrilate grafts, and explain the factors influencing them.

METHODS

The authors collected information of all the patients undergoing cranial reconstructive surgery (N = 149) at the Military Medical Academy in Belgrade. Procedures were performed either using a craniotomy bone flap, removed and replaced in the same act, or using methylmethacrilate. These 2 groups were compared using the Chi-squared test, controlling for the confounding influence of the size of the defect.

RESULTS

Intracranial neoplasms were the cause for the reconstruction in 71.1% of patients. The total complication rate was 7.4%, while the infection rate was 5.4%. The infection rate was significantly higher in those procedures done using methylmethacrilate (11.3% compared with 2.1%, P = 0.017), but when controlling for the confounding effect of the size of the defect treated, the difference in infection rate was significant only in large defects (13.9% compared with 2%, P = 0.031), while for small defects the difference was not statistically significant.

CONCLUSIONS

Our study suggests that the material used for reconstruction of calvaria influences the infection rate only in large and complicated defects. Considering the importance of the reconstruction, further studies should explore and confirm the role of material type on the rate of complications.

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.

Histological assessment of porous custom-made hydroxyapatite implants 6 months and 2.5 years after cranioplasty

Background:

In cranial reconstruction, the features of artificial bone differ. Custom-made porous hydroxyapatite (HAp) implants for cranioplasty have been used all over the world because of their good cosmetic, biocompatibility, and osteoconductive properties. Surgical techniques were analyzed, and histological assessment of new bone formation in the hydroxyapatite was performed.

Methods:

Over a 6-year time period, 41 patients underwent cranioplasty using a custom-made three-dimensional hybrid pore structured hydroxyapatite (3DHPoHAp) implant. The surgical techniques and histological evaluations of 3DHPoHAp in 2 cases, removed 6 months and 2.5 years after cranioplasty, are described.

Results:

Using 3DHPoHAp, cranioplasty was successfully performed for all patients. The implant fit the bone defect exactly, and surgical manoeuvres were simple and easy. All implants were firmly fixed using a titanium plate, and postoperative infection occurred in 1 patient (2.4%). New bone formation was seen in 2 cases 6 months and 2.5 years after cranioplasty. Osteoblasts were progressing to the stoma at various depths, and bone tissue had ripened. Furthermore, lamellar structure was observed in the case at 2.5 years.

Conclusions:

In this study, there was a low infection rate, and new bone formation was seen in vivo after cranioplasty. This study also demonstrated that the 3DHPoHAp implant is a good candidate for cranial bone implants because its good osteoconductivity and biocompatibility.

Reconstruction of a large calvarial traumatic defect using a custom-made porous hydroxyapatite implant covered by a free latissimus dorsi muscle flap in an 11-year-old patient

Reconstruction of complex skull defects requires collaboration between neurosurgeons and plastic surgeons to choose the most appropriate procedure, especially in growing children. The authors describe herein the reconstruction of an extensive traumatic bone and soft tissue defect of the cranial vault in an 11-year-old boy. The size of the defect, quality of the tissues, and patient's initial condition required a 2-stage approach. Ten months after an initial emergency procedure in which lacerated bone and soft tissue were excised, reconstruction was performed. The bone defect, situated on the left frontoparietal region, was 85 cm² and was filled by a custom-made porous hydroxyapatite implant. The quality of the overlying soft tissue did not allow the use of classic local and locoregional coverage techniques. A free latissimus dorsi muscle flap branched on the contralateral superficial temporal pedicle was used and left for secondary healing to take advantage of scar retraction and to minimize alopecia. Stable well-vascularized implant coverage as well as an esthetically pleasing skull shape was achieved. Results in this case suggest that concomitant reconstruction of large calvarial defects by cranioplasty with a custom-made hydroxyapatite implant covered by a free latissimus dorsi muscle flap is a safe and efficient procedure in children, provided that there is no underlying infection of the operative site.

Cranioplasty using custom-made hydroxyapatite versus titanium: a randomized clinical trial

OBJECTIVE

Cranioplasty is routinely performed in neurosurgery. One of its underestimated problems is the high postoperative complication rate of up to 40%. Due to the lack of good prospective studies and the small number of patients (5–20 each year) who receive alloplastic materials, decisions in favor or against a certain material are based on subjective empirical or economic reasons. The main goal of this study—the first prospective, randomized multicenter study in Germany—of custom-made titanium and hydroxyapatite (HA) implants was to compare local and systemic infections related to the implant within the first 6 months after implantation. Secondary objectives included comparing the reoperation rate, the complication rate, clinical and neurological outcomes, and health-related quality of life.

METHODS

The study included patient screening and randomization at 6 to 8 weeks before operation; pre-, intra-, and postoperative documentation until discharge; and postoperative follow-ups after 1 and 6 months. Approval for the study was obtained from the local ethics committee.

RESULTS

A total of 52 patients were included in the study. The rate of local implant–associated wound infection in the HA group was 2 of 26 (7.7%) patients and 5 of 24 (20.8%) patients in the titanium group (p = 0.407). Systemic inflammation within 6 months after operation affected none of the patients in the HA group and 4 of 24 (37.5%) patients in the titanium group (p = 0.107). In both groups, 7 patients required reoperation after the 6-month follow-up (26.9% of the HA group and 29.2% of the titanium group; not significant). Reoperation with an explantation was necessary in 3 patients in each group (11.5% of the HA group and 12.5% of the titanium group; not significant). The results demonstrated a significantly higher number of epidural hematomas in the HA group in comparison with none in the titanium group. Altogether, 46 adverse events were found in 27 patients (54%). An improvement in the neurological outcome after 6 months was experienced by 43% of the patients in the HA group and 26.3% of the patients in the titanium group (p = 0.709).

CONCLUSIONS

The study emphasizes that cranioplasty is a high-risk intervention. In comparison with titanium, HA shows benefits in terms of the infection rate and the neurological outcome, but at the same time has a higher postoperative risk for epidural hematoma. Depending on the individual conditions, both materials have their place in future cranioplasty therapies.

Clinical trial registration no.: NCT00923793 (clinicaltrials.gov).

Predictors of infection after 754 cranioplasty operations and the value of intraoperative cultures for cryopreserved bone flaps

OBJECTIVE

The authors' aim was to report the largest study on predictors of infection after cranioplasty and to assess the predictive value of intraoperative bone flap cultures before cryopreservation.

METHODS

They retrospectively examined all cranioplasties performed between March 2004 and November 2014. Throughout this study period, the standard protocol during initial craniectomy was to obtain a culture swab of the extracted autologous bone flap (ABF)—prior to its placement in cytostorage—to screen for microbial contamination. Two consecutive protocols were employed for the use and interpretation of the intraoperative swab culture results: A) From March 2004 through June 2013, any culture-positive ABF (+ABF) was discarded and a custom synthetic prosthesis was implanted at the time of cranioplasty. B) From July 2013 through November 2014, any ABF with a skin flora organism was not discarded. Instead, cryopreservation was maintained and the +ABF was reimplanted after a 10-minute soak in bacitracin irrigation as well as a 3-minute soak in betadine.

RESULTS

Over the 10.75-year period, 754 cranioplasty procedures were performed. The median time from craniectomy to cranioplasty was 123 days. Median follow-up after cranioplasty was 237 days for protocol A and 225 days for protocol B. The overall infection rate after cranioplasty was 6.6% (50 cases) occurring at a median postoperative Day 31. Staphylococcus spp. were involved as the causative organisms in 60% of cases.

Culture swabs taken at the time of initial craniectomy were available for 640 ABFs as 114 ABFs were not salvageable. One hundred twenty-six (20%) were culture positive. Eighty-nine +ABFs occurred during protocol A and were discarded in favor of a synthetic prosthesis at the time of cranioplasty, whereas 37 +ABFs occurred under protocol B and were reimplanted at the time of cranioplasty.

Cranioplasty material did not affect the postcranioplasty infection rate. There was no significant difference in the infection rate among sterile ABFs (7%), +ABFs (8%), and synthetic prostheses (5.5%; p = 0.425). All 3 +ABF infections under protocol B were caused by organisms that differed from those in the original intraoperative bone culture from the initial craniectomy. A cranioplasty procedure ≤ 14 days after initial craniectomy was the only significant predictor of postcranioplasty infection (p = 0.007, HR 3.62).

CONCLUSIONS

Cranioplasty procedures should be performed at least 14 days after initial craniectomy to minimize infection risk. Obtaining intraoperative bone cultures at the time of craniectomy in the absence of clinical infection should be discontinued as the culture results were not a useful predictor of postcranioplasty infection and led to the unnecessary use of synthetic prostheses and increased health care costs.

Computed tomographic evaluation of novel custom-made artificial bones, "CT-bone", applied for maxillofacial reconstruction

Introduction

We fabricated custom-made artificial bones using three-dimensionally layered manufacturing (3D printing) process, and have applied them to patients with facial deformities. We termed this novel artificial bone the “CT-bone”. The aim of the present study was to evaluate the middle- and long-term safety and effectiveness of the CT-bones after transplantation.

Methods

The subject areas involved were 23 sites of 20 patients with facial bone deformities due to congenital abnormality, tumor, or trauma. The CT-bones were used for augmentation; they were evaluated by CT images, minimally for 1 year and maximally for 7 years and 3 months (3 years and 1 month on average) after transplantation.

Results

No serious systemic events due to the CT-bone graft were found during the observation period (1 year postoperatively). In 4 sites of 4 patients, the CT-bones were removed due to local infection of the surgical wounds at 1–5 years postoperatively. Compatibility of the shapes between the CT-bone and the recipient bone was confirmed to be good during the operation in all of the 20 cases, implying that the CT-bones could be easily installed onto the recipient sites. During the CT evaluation (<7 years and 3 months), no apparent chronological change was seen in the shape of the CT-bones. Sufficient bone union was confirmed in 19 sites. The inner CT values of the CT-bones increased in all the sites. The longer the postoperative period, greater increases in the CT values of the CT-bones tended to be observed.

Conclusions

The CT-bone showed maintenance of the original shape and good bone replacement, based on the middle- and long-term follow-ups. In the future, we would make an intelligent type of artificial bones in which bone regeneration is induced by gradually releasing angiogenesis-inducing factors and/or bone-regeneration-inducing factors at the three-dimensionally controlled positions.

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We fabricated custom-made artificial bones, using a 3D printing process, and have applied them to patients with facial deformities.