A prospective study of computer-aided design and manufacture of titanium plate for cranioplasty and its clinical outcome

Intraoperative extracorporeal irradiation for giant sarcoma-infiltrated calvarium: a case report

Large bone defects that occur after resection of calvarial tumours are commonly remedied using titanium meshes or bone prostheses. However, these methods have several problems. While intraoperative extracorporeal radiotherapy for bone flaps could avoid these problems, there have been only a few reports wherein meningiomas were treated with 120 Gy irradiation. Moreover, no reports are available on calvarial metastasis of sarcoma, and the therapeutic radiation dose remains uncertain. Here, we report a case of giant calvarial metastasis of myxoid liposarcoma treated with intraoperative extracorporeal radiotherapy at a dose of 50 Gy. The treatment resulted in successful tumour control followed by favourable bone reconstruction.

Comparison of Infection Rates Following Immediate and Delayed Cranioplasty for Postcraniotomy Surgical Site Infections: Results of a Meta-Analysis

Postoperative surgical site infections (SSIs) in neurosurgery are rare. However, they pose a formidable challenge to the treating neurosurgeon and substantially worsen patient outcomes. These infections require prompt intervention in the form of débridement, including removal of craniotomy bone. Reconstruction of the craniotomy defect can be performed along with the débridement or can be performed at a later time. Although there have been concerns about performing cranioplasty at the same time as débridement, recent studies have advocated performance of cranioplasty at the same time as the débridement, as it avoids the morbidity associated with having a craniectomy defect and avoids the need for another surgical procedure. We conducted a literature review and meta-analysis to examine the data on immediate cranioplasties and delayed cranioplasties performed for postcraniotomy SSIs. We analyzed 15 articles with a total of 353 patients. Our analysis revealed that the pooled proportion of treatment failure was 10.4% (95% confidence interval [CI] 5.9%-17.8%) when an immediate cranioplasty was done and 16.1% (95% CI 7.2%-32.1%) when delayed cranioplasty was done. The pooled proportion of treatment failure was 12% (95% CI 5.9%-22.9%) when the same bone was used for cranioplasty and was 8% (95% CI 3%-20%) when prosthetic material such as titanium was used for cranial vault reconstruction. Thus, the rate of treatment failure was less when an immediate single-stage cranioplasty was done compared with a delayed cranioplasty following SSIs.

Reconstruction of the Occipital and Parietal Congenital Defect with 3D Custom-Made Titanium Prosthesis: A Case Report with Four and a Half Years of Follow-Up and a Brief Review of Literature

Management of patients with congenital skull defects requires a multidisciplinary approach. Considering the defect's location and size, brain protection, and the cosmetic outcome makes such reconstructions challenging. Due to limited resemblance to skull contour and donor site morbidity of autogenous bone grafts, alloplastic materials are widely used for skull reconstructions. Titanium alloys have proper strength values, low infection rates, favorable osseointegration property, and excellent marginal adaptability when manufactured by computer-aided design (CAD) and computer-aided manufacturing (CAM). A 13-year-old female patient presented with congenital defects at the superior third of occipital bone and posterior thirds of the bilateral parietal bones. On CT scan, the exact size and shape of the defect were determined. Using CAD/CAM, a 3D virtual model of the prosthesis was designed and then printed with titanium alloy (TiAl6V4) via additive manufacturing method. The prosthesis was placed on the defect in a total surgery time of only 90 minutes. On 4.5 years of follow-up, the contour of the skull was ideal and the skin over the defect and neurologic status was intact. Due to their biocompatibility and rigidity, custom-made titanium prostheses are promising options for reconstructing complex skull defects.

Cranioplasty Using Customized 3-Dimensional-Printed Titanium Implants: An International Collaboration Effort to Improve Neurosurgical Care

BACKGROUND

Evolutions in cranioplasty have allowed for the creation of customized implants via advances in 3-dimensional (3D) printing technology, although the high cost associated with this technique presents a barrier for low-income countries. Through an international collaboration, our team in Da Nang, Vietnam is able to create low-cost, customized titanium implants for patients with skull defects. We discuss the details of our collaboration and present our experience with this procedure.

METHODS

We conducted a retrospective review of 35 patients who underwent cranioplasty using custom-made titanium implants. The molding and implant making processes were performed by our neurosurgeons using a 3D printer donated by the United Kingdom-based nongovernmental organization Facing the World. We obtained demographic and preoperative data (reason for skull defect, location, surface area measurement of defect) and postoperative data (complications, cosmetic outcome, and patient satisfaction).

RESULTS

The median patient age was 27 years (range, 16-60 years). Primary indications for craniectomy included traumatic brain injury from motor vehicle accident (77.1%), cerebrovascular disease (11.4%), implant failure following previous cranioplasty (5.7%), and fall (5.7%). Postoperatively, all implants were found to have an excellent fit; at 6-month follow-up, none of the implants required removal. Complications included 4 postoperative hematomas and 1 surgical site infection. All the patients had improved aesthetic appearance and high satisfaction.

CONCLUSIONS

Cranioplasty using customized titanium implants yields excellent results for patients with skull defects, demonstrating the practicality of this technique for cranioplasty in low-income countries. Our experience highlights the importance of ongoing international collaboration to improve neurosurgical care in these countries.

Comparison of two different titanium cranioplasty methods: Custom-made titanium prostheses versus precurved titanium mesh

Background:

The aim of this study was to compare the results of two different titanium cranioplasties for reconstructing skull defects: standard precurved mesh versus custom-made prostheses.

Methods:

Retrospective analysis of 23 patients submitted to titanium cranioplasty between January 2014 and January 2019. Ten patients underwent delayed cranioplasty using custom-made prostheses; and 13 patients were treated using precurved titanium mesh (ten delayed cranioplasties, and three single-stage resection- reconstructions). Demographic, clinical, and radiological data were recorded. Results and complications of the two methods were compared, including duration of surgery, cosmetic results (visual analog scale for cosmesis [VASC]), and costs of the implants.

Results:

Complications: one epidural hematoma in the custom-made group, one delayed failure in precurved group due to wound dehiscence with mesh exposure. There were no infections in either group. All custom-made prostheses perfectly fitted on the defect; eight of 13 precurved mesh prostheses incompletely covered the defect. Custom-made cranioplasty obtained better cosmetic results (average VASC 94 vs. 68), shorter surgical time (141min vs. 186min), and -fewer screws was needed to fix the prostheses in place (6 vs. 15). However, satisfactory results were obtained using precurved mesh in cases of small defects and in single-stage reconstruction. Precurved mesh was found to be cheaper (€1,500 vs. €5,500).

Conclusion:

Custom-made cranioplasty obtained better results and we would suggest that this should be a first choice, particularly for young patients with a large cranial defect. Precurved mesh was cheaper and useful for single-stage resection-reconstruction. Depending on the individual conditions, both prostheses have their place in cranioplasty therapies.

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.

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.

Complications of Cranioplasty

Cranioplasty is a time-honoured surgical procedure to restore the calvarial form and function that is associated with a relatively high complication rate. The present article analyzed various complications and reviewed the complications based on study of the relevant research in the craniofacial literature. Complications were broadly divided into 2 groups, intraoperative and postoperative, for ease of understanding. The etiological factors, local and systemic condition of the patient, prevention, and management of various complications were widely discussed. The article also highlighted problems and complications associated with various reconstructive materials. Insights into various complications of cranioplasty enable surgeon to understand them better, minimize the chances of occurrence, and improve surgical outcome. In spite of reported high rate of complications, serious complications like meningitis, air embolism, and death are rare.

Applications of Computer Technology in Complex Craniofacial Reconstruction

Background:

To demonstrate our use of advanced 3-dimensional (3D) computer technology in the analysis, virtual surgical planning (VSP), 3D modeling (3DM), and treatment of complex congenital and acquired craniofacial deformities.

Methods:

We present a series of craniofacial defects treated at a tertiary craniofacial referral center utilizing state-of-the-art 3D computer technology. All patients treated at our center using computer-assisted VSP, prefabricated custom-designed 3DMs, and/or 3D printed custom implants (3DPCI) in the reconstruction of craniofacial defects were included in this analysis.

Results:

We describe the use of 3D computer technology to precisely analyze, plan, and reconstruct 31 craniofacial deformities/syndromes caused by: Pierre-Robin (7), Treacher Collins (5), Apert’s (2), Pfeiffer (2), Crouzon (1) Syndromes, craniosynostosis (6), hemifacial microsomia (2), micrognathia (2), multiple facial clefts (1), and trauma (3). In select cases where the available bone was insufficient for skeletal reconstruction, 3DPCIs were fabricated using 3D printing. We used VSP in 30, 3DMs in all 31, distraction osteogenesis in 16, and 3DPCIs in 13 cases. Utilizing these technologies, the above complex craniofacial defects were corrected without significant complications and with excellent aesthetic results.

Conclusion:

Modern 3D technology allows the surgeon to better analyze complex craniofacial deformities, precisely plan surgical correction with computer simulation of results, customize osteotomies, plan distractions, and print 3DPCI, as needed. The use of advanced 3D computer technology can be applied safely and potentially improve aesthetic and functional outcomes after complex craniofacial reconstruction. These techniques warrant further study and may be reproducible in various centers of care.

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.

Partial titanium mesh explantation cured post-cranioplasty implant-associated scalp infection

Titanium mesh cranioplasty is routinely used worldwide for skull defect patients given its advantages, such as stability and biocompatibility. However, there are very few reports concerning the treatment of implant-associated scalp infection, which is one of the most common complications. The aim of the study is to retrospectively evaluate a novel operation technique for the treatment of titanium mesh-associated scalp infection post-cranioplasty, namely partial titanium mesh explantation (PTME). A retrospective study was conducted in all patients who underwent surgical treatment for implant-associated scalp infection from January 2012 to September 2016 in our hospital. In total, 17 patients were selected for study analysis among 231 patients who underwent cranioplasty. The treatment success rate of PTME was 85.7%. There was no statistically significant difference in demographics and characteristics except for follow-up length of time between the PTME group and TTME (total titanium mesh explantation) group (Non-paired Student's t-test, P=0.037). While, The PTME group exhibited a significantly reduced skull defect area post-operation compared with the TTME group (Non-paired Student's t-test, P=0.002). Moreover, post-PTME skull area also exhibited a significantly reduced skull defect area compared with the pre-cranioplasty area in the same patient (Non-paired Student's t-test, P=0.006). Compared with traditional surgical treatment of implant-associated scalp infection, PTME combined with strict debridement and antibiotic therapy can cure implant-associated scalp infection. Moreover, PTME could preserve sufficient titanium mesh for brain protection and cosmesis.

Which One Is Better to Reduce the Infection Rate, Early or Late Cranioplasty?

OBJECTIVE

Decompressive craniectomy is an effective therapy to relieve high intracranial pressure after acute brain damage. However, the optimal timing for cranioplasty after decompression is still controversial. Many authors reported that early cranioplasty may contribute to improve the cerebral blood flow and brain metabolism. However, despite all the advantages, there always remains a concern that early cranioplasty may increase the chance of infection. The purpose of this retrospective study is to investigate whether the early cranioplasty increase the infection rate. We also evaluated the risk factors of infection following cranioplasty.

METHODS

We retrospectively examined the results of 131 patients who underwent cranioplasty in our institution between January 2008 and June 2015. We divided them into early (≤90 days) and late (>90 days after craniectomy) groups. We examined the risk factors of infection after cranioplasty. We analyzed the infection rate between two groups.

RESULTS

There were more male patients (62%) than female (38%). The mean age was 49 years. Infection occurred in 17 patients (13%) after cranioplasty. The infection rate of early cranioplasty was lower than that of late cranioplasty (7% vs. 20%; p=0.02). Early cranioplasty, non-metal allograft materials, re-operation before cranioplasty and younger age were the significant factors in the infection rate after cranioplasty (p<0.05). Especially allograft was a significant risk factor of infection (odds ratio, 12.4; 95% confidence interval, 3.24-47.33; p<0.01). Younger age was also a significant risk factor of infection after cranioplasty by multivariable analysis (odds ratio, 0.96; 95% confidence interval, 0.96-0.99; p=0.02).

CONCLUSION

Early cranioplasty did not increase the infection rate in this study. The use of non-metal allograft materials influenced a more important role in infection in cranioplasty. Actually, timing itself was not a significant risk factor in multivariate analysis. So the early cranioplasty may bring better outcomes in cognitive functions or wound without raising the infection rate.

Three-dimensional Physical Modeling: Applications and Experience at Mayo Clinic

Radiologists will be at the center of the rapid technologic expansion of three-dimensional (3D) printing of medical models, as accurate models depend on well-planned, high-quality imaging studies. This article outlines the available technology and the processes necessary to create 3D models from the radiologist's perspective. We review the published medical literature regarding the use of 3D models in various surgical practices and share our experience in creating a hospital-based three-dimensional printing laboratory to aid in the planning of complex surgeries.

Spontaneous fracture of cranioplastic titanium implants without head trauma in an adult: A case report

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The dynamic load was generated at basitemporal skull if prosthesis was not anchored to this loci.

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Via the parietal tuber-temporozygomatic suture line, this dynamic load was passed to the proximal pterion point region, which eventually generated fatigue effects on the prosthesis and eventually fracture.

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The cranioplasty prosthesis shall be well anchored onto the basitemporal skull to prevent fatigue effects of the prosthesis.

Introduction

The cranioplasty is a classical surgical procedure to repair large skull defects. The prosthesis fracture was one rare complication following cranioplasty, which was only known to happen in traumatic head injury or child growing skull.

Presentation of case

In the current report, we documented the first reported case of cranioplasty prosthesis fracture in an adult neurological trauma patient at the proximal pterion point region without head trauma. During the first cranioplasty, due to the cerebromalacia at temporal lobe, patient’s temporalis muscle was not stripped from the dura mater and the prosthesis was anchored outside the temporalis muscle. Thus, no screw was used for anchoring the prosthesis at the basitemporal skull. The prosthesis fracture was observed on 12^th-month post-surgically at the proximal pterion point region. During the second cranioplasty, the temporalis muscle was semi-partitioned from the back due to cerebromalacia recovery and five screws were used to anchor the prosthesis onto the basitemporal skull. The follow-up result was unremarkable on 21^st-month post-second-cranioplasty.

Discussion

A dynamic load was generated on the prosthesis due to head-pillow contact during sleeping. Via the parietal tuber-temporozygomatic suture line, this inward load generates an outward force at the proximal pterion point region, where became a shearing force locating just right below the lowest screw anchoring in this region. This shearing force eventually led to prosthesis fracture at the proximal pterion point due to the fatigue effect.

Conclusion

This case presented the importance of prosthesis anchoring location on the skull, especially when temporalis muscle was required to be preserved due to clinical necessity.

Titanium cranioplasty in children and adolescents

Full thickness calvarial defects present considerable challenges to reconstructive surgeons. In paediatric cases, the use of biomaterials as a substrate for cranioplasty rather than autologous bone is controversial. Alloplastic cranioplasty in adults is supported by several large case series however long term outcome of biomaterial use in paediatric cases is limited. Retrospective seven year analysis of departmental database and clinical records identified 22 patients aged under 18 who had undergone 23 custom made titanium cranioplasties by a single surgeon using the same technique. Data including patient demographics, reason for craniectomy and complications experienced following surgery was obtained. The mean age at operation was 12 years 9 months. The mean defect size was 44.3 cm(2). No significant complications related to the cranioplasty were recorded in the early post operative period or during long term review (average follow up 4 years 6 months). No cranioplasty implant required removal. This retrospective case series shows that custom made patient specific titanium cranioplasty is a viable alternative to autologous bone as a reconstructive material in paediatric patients under specific circumstances.

Applications of three-dimensional printing technology in the cardiovascular field

Three-dimensional (3-D) printing technology has rapidly developed in the last few decades. Meanwhile, the application of this technology has reached beyond the engineering field and expanded to almost all disciplines, including medicine. There has been much research on the medical applications of 3-D printing in neurosurgery, orthopedics, maxillofacial surgery, plastic surgery, tissue engineering, as well as other fields. Because of the complexity of the cardiovascular system, the application of this technology is limited and difficult, as compared to other disciplines, and thus there is much room for future development. Many of the difficulties associated with this technology must be overcome. Nonetheless, there is no doubt that 3-D printing technology will benefit patients with cardiovascular diseases in the near future.

Management of extensive frontal cranioplasty defects

Cranioplasty is a medical technique to correct cranial bone defects. Depending on the size and location of the defect, a bone substitute can be used to replace the missing bone. Frontal bone defects are important to patients in terms of cosmetics because they are visible. Advances in computer design allow the production of customized implants with improved cosmetic and functional results. This report describes hybrid optimization of three-dimensional technological methods along with traditional methods toward the manufacture of deep-buried titanium implants, restoring frontal skull defects for 4 patients. A three-dimensional model was produced from the computed tomographic scan data of 3 patients using an in-house three-dimensional printer. A new approach was followed in treating the fourth patient. The defect was restored using preoperative scan before cranioplasty. These data were transported digitally into the defect skull to recreate the bone contour required, and a three-dimensional model was produced from the "new" digital model using the three-dimensional printer. Defect areas of the patients were large and measured 101.21 × 123.35 (vertical × horizontal) in average (mm). Conventional wax-up of the defect was carried to restore normal conformity. A titanium sheet (0.5 mm) was swaged into the desired shape; however, convexity of the defect area makes titanium swaging challenging, especially at the deep lateral undercuts. Making side flanges at reasonable lengths made it easy to swage without creasing. Three-dimensional models aided to produce accurately fitting plates. Finally, the sequential method of using both digital and manual procedures is a low-cost, reliable, accurate, and reproducible method.

A simple method for controlled reduction duraplasty during cranioplasty

BACKGROUND

Bone flap re-approximation during cranioplasty can be complicated by underlying pseudomeningocele or meningoencephalocele. A technique for controlled reduction duraplasty to aid bone flap positioning is suggested.

METHODS

A simple method using bipolar electrocautery in a predetermined radial pattern from the center of defect is described. Localized tissue contraction allows controlled reduction in the surface area and degree of protrusion. This in turn facilitates bone flap positioning.

RESULTS

The main advantage of this technique is slow and evenly distributed pressure conferred by controlled tissue contraction using multiple radial coagulation lines. No technical difficulties or complications have occurred with this method during cranioplasty for 11 patients.

CONCLUSION

This simple technique for controlled reduction duraplasty can provide an easy and efficient method for bone flap re-approximation, and add to the existing techniques for a commonly performed procedure.

Complications of cranioplasty after decompressive craniectomy for traumatic brain injury

INTRODUCTION

Decompressive craniectomy (DC)--a potentially life-saving intervention following traumatic brain injury (TBI) with medically refractory brain swelling--once performed, surviving patients, more often than not, undergo a second procedure with cranioplasty (CP) in the future. This study analyzes complications following CP after DC, as the beneficial effects of the DC can't be extrapolated in long run over a population unless one adds into it the complications associated with the CP in the survivors of TBI.

MATERIALS AND METHODS

An observational study was performed retrospectively, with the review of case records. Demographic, clinical, and outcome data were collected, and complications were studied for any predictive parameters. A multivariate analysis was performed to identify factors that influenced these complications.

RESULTS

Data were collected for a total of 74 patients who underwent CP with a median age of 32, and a mean follow-up time of 2 years and 8 months. The mortality rate was 1.35% and overall complication rate 31%. The most significant factor determining complications were operating time more than 90 min Odds ratio (OR) 4.77 (1.61-14.20); timing of CP less than 3 months after craniectomy, OR 2.86 (1.48-8.11); age more than 20 years, OR 2.59 (1.20-6.53); and female gender, OR 1.91 (1.13-4.17).

CONCLUSIONS

Although considered as a straight-forward procedure, the risks associated with this elective procedure should be kept in mind by the surgeon so that the patients and families can be apprised judiciously. It should be ascertained that patient and/or family consents for the procedure after being appropriately informed about the benefits and risks associated with the procedure.

Role of a dentist in comprehensive management of a comatose patient with post traumatic head injury and neuropathological chewing

Injury of the head and neck region can result in substantial morbidity. Comprehensive management of such patients requires team work of several specialties, including dentists. A young female patient with extensive loss of cranium and associated pathological chewing was referred to the dental department. The lost cranium was replaced by a custom-made, hand-fabricated cranioplast. Trauma due to pathological mastication was reduced by usage of a custom-made mouthguard. Favorable results were seen in the appearance of the patient and after insertion of the mouthguard as evidenced in good healing response. The intricate role of a dental specialist in the team to manage a patient with post traumatic head injury has been highlighted. The take away message is to make the surgical fraternity aware of the scope of dentistry in the comprehensive management of patients requiring special care.

Cranioplasty with autologous cryopreserved bone after decompressive craniectomy: complications and risk factors for developing surgical site infection

Background

Renewed interest has developed in decompressive craniectomy, and improved survival is shown when this treatment is used after malignant middle cerebral artery infarction. The aim of this study was to investigate the frequency and possible risk factors for developing surgical site infection (SSI) after delayed cranioplasty using autologous, cryopreserved bone.

Methods

This retrospective study included 74 consecutive patients treated with decompressive craniectomy during the time period May 1998 to October 2010 for various non-traumatic conditions causing increased intracranial pressure due to brain swelling. Complications were registered and patient data was analyzed in a search for predictive factors.

Results

Fifty out of the 74 patients (67.6 %) survived and underwent delayed cranioplasty. Of these, 47 were eligible for analysis. Six patients (12.8 %) developed SSI following the replacement of autologous cryopreserved bone, whereas bone resorption occurred in two patients (4.3 %). No factors predicted a statistically significant rate of SSI, however, prolonged procedural time and cardiovascular comorbidity tended to increase the risk of SSI.

Conclusions

SSI and bone flap resorption are the most frequent complications associated with the reimplantation of autologous cryopreserved bone after decompressive craniectomy. Prolonged procedural time and cardiovascular comorbidity tend to increase the risk of SSI.

Cranioplasty with custom-made titanium plates--14 years experience

BACKGROUND

There is no consensus on which material is best suited for repair of cranial defects.

OBJECTIVE

To investigate the outcomes following custom-made titanium cranioplasty.

METHODS

The medical records for all patients who had titanium cranioplasty at 2 major neurosurgical centers in Western Australia were retrieved and analyzed for this retrospective cohort study.

RESULTS

Altogether, 127 custom-made titanium cranioplasties on 113 patients were included. Two patients had 3 titanium cranioplasties and 10 patients had 2. Infected bone flap (n = 61, 54%), either from previous craniotomy or autologous cranioplasty, and contaminated bone flap (n = 16, 14%) from the initial injury were the main reasons for requiring titanium cranioplasty. Complications attributed to titanium cranioplasty were common (n = 33, 29%), with infection being the most frequent complication (n = 18 patients, 16%). Complications were, on average, associated with an extra 7 days of hospital stay (interquartile range 2-17). The use of titanium as the material for the initial cranioplasty (P = .58), the presence of skull fracture(s) (P > .99) or scalp laceration(s) (P = .32) at the original surgery, and proven local infection before titanium cranioplasty (P = .78) were not significantly associated with an increased risk of infection. Infection was significantly more common after titanium cranioplasty for large defects (hemicraniectomy [39%] and bifrontal craniectomy [28%]) than after cranioplasty for small defects (P = .04).

CONCLUSION

Complications after using titanium plate for primary or secondary cranioplasty were common (29%) and associated with an increased length of hospital stay. Infection was a major complication (16%), and this suggested that more vigorous perioperative infection prophylaxis is needed for titanium plate cranioplasty.

Seven years of cranioplasty in a regional neurosurgical centre

INTRODUCTION

In recent years craniectomy has been widely used in the management of traumatic brain injury and ischaemic stroke. The objective of this study was to evaluate the indications, techniques and outcomes for patients undergoing cranioplasty over a recent 7-year period in a geographically distinct population.

MATERIALS AND METHODS

An observational study was performed retrospectively, with review of case records from 2004 to 2011. Demographic, clinical and outcome data were collected, and complications were classified as major and minor. A multi-variant analysis was performed to identify patient and management factors that influenced outcome.

RESULTS

Data were collected on a total of 87 cranioplasty patients with a median age of 42 and a mean follow-up time of 3 years and 10 months. The main indications for craniectomy were trauma (46%), infection (19%) intracranial haemorrhage (15%), tumour (13%) and ischaemic stroke (6%). Eight percent of patients had a synchronous craniectomy and cranioplasty, 14% had cranioplasty within 3 months of craniectomy, 21% within 3-6 months, 35% within 6-12 months, 14% over 1 year and 8% over 2 years later. The most frequently implanted cranioplasty material was titanium (53%), followed by autologous bone (26%) and acrylic (15%). Administration of prophylactic antibiotics was recorded in 97% of cases. Major complications occurred in 20% of patients, including 2 deaths (2%), 5 extradural haemorrhages (6%) and 9 infections (10%). A further 10% of cases experienced minor or cosmetic complications.

CONCLUSIONS

Cranioplasty is often considered as a low-risk procedure following craniectomy. In our cohort, a 20% risk of major complications, including death, was identified. These findings contribute to the literature, emphasising that cranioplasty is a high-risk procedure. Whilst compelling reasons may guide the undertaking of craniectomy, it is essential that consideration is given to the significant subsequent risks of cranioplasty.

Prefabricated patient-matched cranial implants for reconstruction of large skull defects

Cranial defects can be caused by injury, infection, or tumor invasion. Large defects should be reconstructed to protect the brain and normalize the cerebral hemodynamics. The conventional method is to cover the defect with bone cement. Custom-made implants designed for the individual patient are now available. We report our experience with one such product in patients with large cranial defects (>7.6 cm in diameter). A CT scan with 2 mm slices and a three-dimensional reconstruction were obtained from the patient. This information was dispatched to the company and used as a template to form the implant. The cranial implant was received within four weeks. From 2005 to 2010, custom-made cranial implants were used in 13 patients with large cranial defects. In 10 of the 13 patients, secondary deep infection was the cause of the cranial defect. All the implants fitted well or very well to the defect. No infections were seen after implantation; however, one patient was reoperated on for an epidural hematoma. A custom-made cranial implant is considerably more expensive than an implant made of bone cement, but ensures that the defect is optimally covered. The use of custom-made implants is straightforward and timesaving, and they provide an excellent medical and cosmetic result.

Shape modifications of porous hydroxyapatite prostheses to improve rigid implant fixation: Experience in 12 cases

BACKGROUND

Various methods of fixation have been described for custom made hydroxyapatite cranial implants. Their poor malleability limits most of the common used fixation techniques because of the high risk of cranioplasty's fracturing or higher exposure to infections. We present our experience with a new fixation technique, based on an appositely premodified hydroxyapatite implants.

METHODS

In a 2-year time period, 12 patients underwent cranioplasty by a modified custom made porous hydroxyapatite implant. Once the three-dimensional computer model of the prostheses was performed, three semicircular extensions placed at strategic positions were drawn and the final prosthesis was realized. At surgery, holes fitting the extensions were drilled into the skull borders and the implant was easily embedded inside the defect. Small titanium meshes overlying the extensions were fixed by screws to the surrounding bone.

RESULTS

A minimal increase of operative times was recorded, with drilling and fixation requiring additional 30 and 15 minutes, respectively. Optimal contact between cranioplasty and skull borders was always observed at control computed tomography (CT) scans. Permanent rigid fixation was obtained in all cases, with good functional and aesthetic results at follow-up.

CONCLUSIONS

Modifications of hydroxyapatite implants are obtained without additional costs. The minimal increase of operative times is largely counterbalanced by optimal fixation results. Finally, the bone drilling and the immediate proximity of bone to prosthesis might enhance the potential for osteogenesis and osteointegration.

Prevention of postoperative cerebrospinal fluid leaks with multilayered reconstruction using titanium mesh-hydroxyapatite cement cranioplasty after translabyrinthine resection of acoustic neuroma

OBJECT

Several prophylactic surgical methods have been tried to prevent CSF leakage after translabyrinthine resection of acoustic neuroma (TLAN). The authors report an improvised technique for multilayer watertight closure using titanium mesh-hydroxyapatite cement (HAC) cranioplasty in addition to dural substitute and abdominal fat graft after TLAN.

METHODS

The study was limited to 42 patients who underwent TLAN at University Hospitals Case Medical Center using this new technique from 2006 to 2012. Systematic closure of the surgical wound in layers using temporalis fascia, dural substitute, dural sealant, adipose graft, titanium mesh, and then HAC was performed in each case. Temporalis muscle and eustachian tube obliteration were not used. The main variables studied were patient age, tumor size, tumor location, cosmetic outcome, length of hospitalization, and the incidence of CSF leak, pseudomeningocele, and infection.

RESULTS

Excellent cosmetic outcome was achieved in all patients. There were no cases of postoperative CSF rhinorrhea, incisional CSF leak, or meningitis. Cosmetic results were comparable to those achieved using HAC alone. This cost-effective technique used only a third of the HAC required for traditional closure in which the entire mastoid defect is filled with cement, predisposing to infection. Postoperative CT and MRI showed excellent bony contouring and dural reconstitution, respectively.

CONCLUSIONS

The authors report on successful use of titanium mesh-HAC cranioplasty in preventing postoperative CSF leak after TLAN in all cases in their series. The titanium mesh provides a well-defined anatomical dissection plane that would make reoperation easier than working through scarred soft tissue. The mesh bolsters the fat graft and keeps HAC out of direct contact with mastoid air cells, thereby reducing the risk of infection. The cement cranioplasty does not preclude subsequent implantation of a bone-anchored hearing aid.

Use of "custom made" porous hydroxyapatite implants for cranioplasty: postoperative analysis of complications in 1549 patients

Background:

Cranioplasty is a surgical intervention aimed at reestablishing the integrity of skull defects, and should be considered the conclusion of a surgical act that began with bone flap removal. Autologous bone is still considered the treatment of choice for cranioplasty. An alternative choice is bioceramic porous hydroxyapatite (HA) as it is one of the materials that meets and comes closest to the biomimetic characteristics of bone.

Methods:

The authors analyzed the clinical charts, compiled by the neurosurgeon, of all patients treated with custom-made porous HA devices (Custom Bone Service Fin-Ceramica, Faenza) from which epidemiological and pathological data as well as material-related complications were extrapolated.

Results:

From November 1997 to December 2010, 1549 patients underwent cranioplasty with the implantation of 1608 custom-made porous HA devices. HA was used in 53.8% of patients for decompressive craniectomy after trauma or intracranial hemorrhage, while the remaining cases were for treated for comminuted fracture, cutaneous or osseous resection, cranial malformation, autologous bone reabsorption or infection or rejection of previously implanted material. The incidence of adverse events in patients treated for cranioplasty, as first line treatment was 4.78% (56 events/1171 patients), and 5.02%, (19 events/378 patients) at second line.

Conclusion:

This study demonstrates that HA is a safe and effective material, is well tolerated in both adult and pediatric patients, and meets the requirements necessary to repair craniolacunia.

Immediate titanium cranioplasty after debridement and craniectomy for postcraniotomy surgical site infection

BACKGROUND

For postcraniotomy surgical site infection (SSI) involving the bone, typical management involves craniectomy, debridement, and delayed cranioplasty. Disadvantages to delayed cranioplasty include cosmetic deformity, vulnerability of unprotected brain, and risks and costs associated with an additional operation. Many authors have attempted bone flap salvage by using various techniques.

OBJECTIVE

We evaluate our experience with immediate titanium mesh cranioplasty at the time of craniectomy and debridement.

METHODS

We retrospectively reviewed SSIs in patients that underwent craniotomy for treatment of a brain tumor. These patients were treated with craniectomy, debridement, and immediate titanium mesh cranioplasty followed by antibiotics. The primary outcome was recurrent infection.

RESULTS

Twelve patients met the inclusion criteria. Risk factors for infection included preoperative radiation therapy (33%), prior craniotomy (33%), and postoperative CSF leak (25%). Median follow-up was 14 months. Ten (83%) patients had long-term resolution without recurrent infection. One patient required additional surgical debridement for persistent infection with successful placement of new titanium mesh. Another patient developed recurrent infection but opted for hospice care because of tumor progression.

CONCLUSION

This series demonstrates the safety and feasibility of performing immediate titanium cranioplasty at the time of craniectomy and debridement in patients with postcraniotomy infections. This has been shown in patients with risk factors for poor wound healing. Immediate cranioplasty avoids the drawbacks, risks, and costs of delayed cranioplasty.

Cranioplasty prosthesis manufacturing based on reverse engineering technology

Background

Most patients with large focal skull bone loss after craniectomy are referred for cranioplasty. Reverse engineering is a technology which creates a computer-aided design (CAD) model of a real structure. Rapid prototyping is a technology which produces physical objects from virtual CAD models. The aim of this study was to assess the clinical usefulness of these technologies in cranioplasty prosthesis manufacturing.

Material/Methods

CT was performed on 19 patients with focal skull bone loss after craniectomy, using a dedicated protocol. A material model of skull deficit was produced using computer numerical control (CNC) milling, and individually pre-operatively adjusted polypropylene-polyester prosthesis was prepared. In a control group of 20 patients a prosthesis was manually adjusted to each patient by a neurosurgeon during surgery, without using CT-based reverse engineering/rapid prototyping. In each case, the prosthesis was implanted into the patient. The mean operating times in both groups were compared.

Results

In the group of patients with reverse engineering/rapid prototyping-based cranioplasty, the mean operating time was shorter (120.3 min) compared to that in the control group (136.5 min). The neurosurgeons found the new technology particularly useful in more complicated bone deficits with different curvatures in various planes.

Conclusions

Reverse engineering and rapid prototyping may reduce the time needed for cranioplasty neurosurgery and improve the prosthesis fitting. Such technologies may utilize data obtained by commonly used spiral CT scanners. The manufacturing of individually adjusted prostheses should be commonly used in patients planned for cranioplasty with synthetic material.

The future of dental devices is digital

OBJECTIVES

Major changes are taking place in dental laboratories as a result of new digital technologies. Our aim is to provide an overview of these changes. In this article the reader will be introduced to the range of layered fabrication technologies and suggestions are made how these might be used in dentistry.

METHODS

Key publications in English from the past two decades are surveyed.

RESULTS

The first digital revolution took place many years ago now with the production of dental restorations such as veneers, inlays, crowns and bridges using dental CAD-CAM systems and new improved systems appear on the market with great rapidity. The reducing cost of processing power will ensure that these developments will continue as exemplified by the recent introduction of a new range of digital intra-oral scanners. With regard to the manufacture of prostheses this is currently dominated by subtractive machining technology but it is inevitable that the additive processing routes of layered fabrication, such as FDM, SLA, SLM and inkjet printing, will start to have an impact. In principle there is no reason why the technology cannot be extended to all aspects of production of dental prostheses and include customized implants, full denture construction and orthodontic appliances. In fact anything that you might expect a dental laboratory to produce can be done digitally and potentially more consistently, quicker and at a reduced cost.

SIGNIFICANCE

Dental device manufacturing will experience a second revolution when layered fabrication techniques reach the point of being able to produce high quality dental prostheses. The challenge for the dental materials research community is to marry the technology with materials that are suitable for use in dentistry. This can potentially take dental materials research in a totally different direction.

Immediate titanium mesh cranioplasty for treatment of postcraniotomy infections

OBJECTIVE

Postcraniotomy infections have generally been treated by debridement of infected tissues, disposal of the bone flap, and delayed cranioplasty several months later to repair the resulting skull defect. Debridement followed by retention of the bone flap has also been advocated. Here we propose an alternative operative strategy for the treatment of postcraniotomy infections.

METHODS

Two patients presenting with clinical and radiographic signs and symptoms of postcraniotomy infections were treated by debridement, bone flap disposal, and immediate titanium mesh cranioplasty. The patients were subsequently administered antibiotics, and their clinical courses were followed.

RESULTS

The patients treated in this fashion did not have recurrence of their infections during 3-year follow-up periods.

CONCLUSIONS

Surgical debridement, bone flap disposal, and immediate titanium mesh cranioplasty may be a suitable option for the treatment of postcraniotomy infections. This treatment strategy facilitates the eradication of infectious sources and obviates the risks and costs associated with a second surgical procedure.

Autogenous skull flaps stored frozen for more than 6 months: do they remain viable?

Autogenous cranioplasties with cryopreserved skull flaps are associated with disproportionately high infection and bone resorption rates. Bone flap non-viability may be a contributing factor. Viable osteoblasts have been cultured recently from cryopreserved long bones. Cryopreserved skull bone may also remain viable based on histological observations. However, cell culture studies have not been performed on skull bone to assess viability. Bone explant cell cultures were performed on 27 skull flaps stored at -30 °C for more than 6 months. Biopsies were taken from the flaps, washed in phosphate buffer saline and cultured in Dulbecco's Modified Eagle's medium at 37 °C in 5% carbon dioxide for 3 weeks. Fresh skull bone samples served as controls. While control samples showed growth of osteoblasts, no osteoblasts were cultured from the study specimens at 3 weeks. In conclusion, skull flaps cryopreserved at -30 °C for more than 6 months are non-viable. Further research characterizing impact of different storage conditions on skull flap viability is warranted.