Assessment of brain injury characterization and influence of modeling approaches.

In this study, using computational biomechanics models, we investigated influence of the skull-brain interface modeling approach and the material property of cerebrum on the kinetic, kinematic and injury outputs. Live animal head impact tests of different severities were reconstructed in finite element simulations and DAI and ASDH injury results were compared. We used the head/brain models of Total HUman Model for Safety (THUMS) and Global Human Body Models Consortium (GHBMC), which had been validated under several loading conditions. Four modeling approaches of the skull-brain interface in the head/brain models were evaluated. They were the original models from THUMS and GHBMC, the THUMS model with skull-brain interface changed to sliding contact, and the THUMS model with increased shear modulus of cerebrum, respectively. The results have shown that the definition of skull-brain interface would significantly influence the magnitude and distribution of the load transmitted to the brain. With sliding brain-skull interface, the brain had lower maximum principal stress compared to that with strong connected interface, while the maximum principal strain slightly increased. In addition, greater shear modulus resulted in slightly higher the maximum principal stress and significantly lower the maximum principal strain. This study has revealed that using models with different modeling approaches, the same value of injury metric may correspond to different injury severity.

Quantitative Assessment of Point-of-Care 3D-Printed Patient-Specific Polyetheretherketone (PEEK) Cranial Implants.

Recent advancements in medical imaging, virtual surgical planning (VSP), and three-dimensional (3D) printing have potentially changed how today's craniomaxillofacial surgeons use patient information for customized treatments. Over the years, polyetheretherketone (PEEK) has emerged as the biomaterial of choice to reconstruct craniofacial defects. With advancements in additive manufacturing (AM) systems, prospects for the point-of-care (POC) 3D printing of PEEK patient-specific implants (PSIs) have emerged. Consequently, investigating the clinical reliability of POC-manufactured PEEK implants has become a necessary endeavor. Therefore, this paper aims to provide a quantitative assessment of POC-manufactured, 3D-printed PEEK PSIs for cranial reconstruction through characterization of the geometrical, morphological, and biomechanical aspects of the in-hospital 3D-printed PEEK cranial implants. The study results revealed that the printed customized cranial implants had high dimensional accuracy and repeatability, displaying clinically acceptable morphologic similarity concerning fit and contours continuity. From a biomechanical standpoint, it was noticed that the tested implants had variable peak load values with discrete fracture patterns and failed at a mean (SD) peak load of 798.38 ± 211.45 N. In conclusion, the results of this preclinical study are in line with cranial implant expectations; however, specific attributes have scope for further improvements.

In vitro and in vivo assessment of glucose cross-linked gelatin/zein nanofibrous scaffolds for cranial bone defects regeneration.

The purpose of this study was to evaluate the glucose cross-linked gelatin/zein scaffolds for bone regeneration in vitro and in vivo. The nanofibrous scaffolds exhibited fast mineralization in the concentrated simulated body fluid with the deposited octacalcium phosphate and dicalcium phosphate dehydrate. The nanofibrous scaffolds exhibited no cytotoxic effect on MC3T3e1 cells in a CCK-8 test. Additionally, scanning electron microscope and confocal laser scanning microscopy images revealed that all the scaffolds were biocompatible and showed excellent support for MC3T3e1 cells. In the osteogenesis characterizations, Alizarin Red staining experiments indicated the improved calcium deposits on the cross-linked scaffolds, while the alkaline phosphatase activity showed no difference. Furthermore, the in vivo cranial bone regeneration results suggested that the cross-linked gelatin/zein scaffolds presented a strong positive effect on the cranial bone regeneration with the increased new bone volume and connective tissue formation, but the incorporation of zein in the gelatin scaffolds did not favor the bone regeneration. Moreover, the cross-linked gelatin scaffold retarded the bone resorption as indicated by the higher levels of IFN-γ and lower levels of IL-6, which restricted the differentiation of osteoclasts.

Assessment of polyurethane spheres as surrogates for military ballistic head injury.

SYNBONE® spheres were impacted with 7.62 × 39 mm mild steel core ammunition at a mean impact velocity of 654 m/s, SD 7 m/s, to simulate engagement distances of around 50-100 m. The wounds and fracture patterns were assessed by two forensic pathologists familiar with military cranial injury. The overall fracture pattern was assessed as being too comminuted when compared with actual injury. This suggests the SYNBONE® spheres have less utility for simulating military injury than other purposes described in the literature.

Assessment of mechanical properties of human head tissues for trauma modelling.

Many discrepancies are found in the literature regarding the damage and constitutive models for head tissues as well as the values of the constants involved in the constitutive equations. Their proper definition is required for consistent numerical model performance when predicting human head behaviour, and hence skull fracture and brain damage. The objective of this research is to perform a critical review of constitutive models and damage indicators describing human head tissue response under impact loading. A 3D finite element human head model has been generated by using computed tomography images, which has been validated through the comparison to experimental data in the literature. The threshold values of the skull and the scalp that lead to fracture have been analysed. We conclude that (1) compact bone properties are critical in skull fracture, (2) the elastic constants of the cerebrospinal fluid affect the intracranial pressure distribution, and (3) the consideration of brain tissue as a nearly incompressible solid with a high (but not complete) water content offers pressure responses consistent with the experimental data.

Assessment of bone repair in critical-size defect in the calvarium of rats after the implantation of tricalcium phosphate beta (ß-TCP).

OBJECTIVES: Evaluating the osteoconductive property of tricalcium phosphate beta (ß-TCP) in comparison to that of inorganic bovine bone for repair in a critical-size defect in the rat calvarium. MATERIALS AND METHODS: Critical-size defects of 7mm were made with a trephine in the calvaria of 48 Wistar rats. The animals were divided into four groups, and the defects in each group were filled with tricalcium phosphate beta (ß-TCP), inorganic bovine bone (Bio-Oss), autogenous bone, or left empty. The animals were euthanized at two different time points (30 and 60days post-operation). All defects were recovered with a absorbable membrane of bovine cortical bone. Histological, histometric, and immunohistochemical (osteocalcin) assessments were carried out at 30 and 60days post-operation. RESULTS: At 30days post-operation, all groups showed areas of bone formation, predominantly when autogenous grafts were used. However, there were no statistically significant differences between the treatment groups (p>0.05). After 60days, there were similarities in the bone formation patterns between the ß-TCP (26.32±) and Bio-Oss (17.35±) groups (p=0.549). In terms of the immunohistochemical assessment of osteocalcin, the clot group showed light to moderate staining at 30 and 60days. The autogenous group showed moderate staining at 30days and moderate to intense staining after 60days. The Bio-Oss group showed light to moderate staining after 30days and intense staining at 60days. The ß-TCP group showed moderate staining at 30 and 60days post-operation. CONCLUSION: ß-TCP is a good osteoconductive material with similar effects to those of inorganic bovine bone graft and is suitable for utilization in the repair of bone defects.

Multi-modal imaging for assessment of tissue-engineered bone in a critical-sized calvarial defect mouse model.

Tissue-engineered bone (TEB) analysis in vivo relies heavily on tissue histological and end-point evaluations requiring the sacrifice of animals at specific time points. Due to differences in animal response to implanted tissues, the conventional analytical methods to evaluate TEB can introduce data inconsistencies. Additionally, the conventional methods increase the number of animals required to provide an acceptable statistical power for hypothesis testing. Alternatively, our non-invasive optical imaging allows for the longitudinal analysis of regenerating tissue, where each animal acts as its own control, thus reducing overall animal numbers. In our 6 month feasibility study, TEB, consisting of a silk protein scaffold with or without differentiated mesenchymal stem cells, was implanted in a critical-sized calvarial defect mouse model. Osteogenesis of the TEB was monitored through signal variation, using magnetic resonance imaging (MRI) and near-infrared (NIR) optical imaging with IRDye® 800CW BoneTagTM (800CW BT, a bone-specific marker used to label osteogenically differentiated mesenchymal stem cells and mineralization). Histological endpoint measurements and computed tomography (CT) were used to confirm imaging findings. Anatomical MRI revealed decreased signal intensity, indicating mineralization, in the TEB compared to the control (i.e. silk scaffold only) at various growth stages. NIR optical imaging results demonstrated a signal intensity increase of the TEB compared to control. Interpretation of the imaging results were confirmed by histological analysis. Specifically, haematoxylin and eosin staining revealing de novo bone in TEB showed that 80% of the defect was covered by TEB, while only 40% was covered for the control. Taken together, these results demonstrate the potential of multi-modal non-invasive imaging to visualize and quantify TEB for the assessment of regenerative medicine strategies. Copyright © 2015 John Wiley & Sons, Ltd.

Resource scarcity drives lethal aggression among prehistoric hunter-gatherers in central California.

The origin of human violence and warfare is controversial, and some scholars contend that intergroup conflict was rare until the emergence of sedentary foraging and complex sociopolitical organization, whereas others assert that violence was common and of considerable antiquity among small-scale societies. Here we consider two alternative explanations for the evolution of human violence: (i) individuals resort to violence when benefits outweigh potential costs, which is likely in resource poor environments, or (ii) participation in violence increases when there is coercion from leaders in complex societies leading to group level benefits. To test these hypotheses, we evaluate the relative importance of resource scarcity vs. sociopolitical complexity by evaluating spatial variation in three macro datasets from central California: (i) an extensive bioarchaeological record dating from 1,530 to 230 cal BP recording rates of blunt and sharp force skeletal trauma on thousands of burials, (ii) quantitative scores of sociopolitical complexity recorded ethnographically, and (iii) mean net primary productivity (NPP) from a remotely sensed global dataset. Results reveal that sharp force trauma, the most common form of violence in the record, is better predicted by resource scarcity than relative sociopolitical complexity. Blunt force cranial trauma shows no correlation with NPP or political complexity and may reflect a different form of close contact violence. This study provides no support for the position that violence originated with the development of more complex hunter-gatherer adaptations in the fairly recent past. Instead, findings show that individuals are prone to violence in times and places of resource scarcity.

The Use of Integra Dermal Regeneration Template Versus Flaps for Reconstruction of Full-Thickness Scalp Defects Involving the Calvaria: A Cost-Benefit Analysis.

BACKGROUND: INTEGRA® Dermal Regeneration Template is a well-known and widely used acellular dermal matrix. Although it helps to solve many challenging problems in reconstructive surgery, the product cost may make it an expensive alternative compared to other reconstruction procedures. This retrospective study aims at comparing INTEGRA-based treatment to flap surgery in terms of cost and benefit. PATIENTS AND METHODS: We considered only patients treated for scalp defects with bone exposure in order to obtain two groups as homogeneous as possible. We identified two groups of patients: 17 patients treated with INTEGRA and 18 patients treated with flaps. All patients were admitted in our institution between 2004 and 2010, and presented a defect of the scalp following trauma or surgery for cancer, causing a loss of the soft tissues of the scalp with bone exposure without pericranium. To calculate the cost in constant euros of each treatment, three parameters were evaluated for each patient: cost of the surgical procedure (number of doctors and nurses involved, surgery duration, anesthesia, material used for surgery), hospitalization cost (hospitalization duration, dressings, drugs, topical agents), and outpatient cost (number of dressing changes, personnel cost, dressings type, anti-infective agents). The statistical test used in this study was the Wilcoxon Mann-Whitney (α = 0.05). RESULTS: No significant difference was characterized between the two groups for gender, age, presence of diabetes, mean defect size, and number of surgical procedures. All patients healed with good quality and durable closure. The median total cost per patient was €11,121 (interquartile range (IQR) 8327-15,571) for the INTEGRA group and €7259 (IQR 1852-24,443) for the flap group (p = 0.34). A subgroup of patients (six patients in the INTEGRA group and five patients in the flap group) showing defects larger than 100 cm2 were considered in a second analysis. Median total cost was €11,825 (IQR 10,695-15,751) for the INTEGRA group and €23,244 (IQR 17,348-26,942) for the flap group. CONCLUSION: Both treatments led to a good healing of the lesions with formation of soft and resistant tissue. No significant difference was characterized between the two groups for days of hospitalization and costs. In cases of patients with defects larger than 100 cm2 for whom major surgery is needed, the treatment with INTEGRA seemed to be less expensive than the treatment with free flaps or pedicle flaps. LEVEL OF EVIDENCE V: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the A5 online Instructions to Authors. www.springer.com/00266 .

An assessment of the usefulness of a coconut as a model of the human skull for forensic identification of a homicide weapon.

The authors made an attempt to verify if a coconut can be used as a model of human skull to determine the homicide weapon. During our experiment 27 strike attempts were performed with the use of 9 different tools. Among them there were authentic murder weapons and instruments which had been used in similar experiments conducted on human skulls in 1955. Depending on the size of an area in contact with a coconut, weapons caused dents corresponding to the shape of a weapon, irregular fractures or long linear cracks. Our results have shown that coconut can be used as an inexpensive screening model of human skull, but only to determine fractures made by tools with small striking surface.

Measuring surgical competency in facial trauma: the Arch Bar Placement Assessment Scale.

BACKGROUND: Surgical education is in a period of significant change. Assessment of surgical competency is imprecise compared with cognitive knowledge and judgment. A surgical competency measurement tool may be useful for plastic surgery training programs and certification societies. We present a validation study of a novel measurement instrument for arch bar placement and dental wire handling. METHODS: An Arch Bar Placement Assessment Scale (ABPAS) was created via consensus by 2 craniofacial and 2 maxillofacial surgeons. Residents and faculty members of plastic and maxillofacial surgery (n = 20) then placed an arch bar on the lower jaw of a skull model. Performances were video recorded without revealing identities. Two study groups were created based on subjects experience level: group 1 (n = 10) previously placed fewer than 25 arch bars; group 2 (n = 10) previously placed more than 25 arch bars. Two craniofacial surgeons used the ABPAS to blindly grade surgical performance. RESULTS: The ABPAS consisted of a 48-point rating scale that included a 23-point task-specific work list and a 25-point global rating scale. Pearson coefficient showed limited intraobserver (P = 0.97) and interobserver (P = 0.95) variance of test scores. The ABPAS demonstrated superior performance in group 2 in the task-specific work list [12.6 (5.5) vs 17.6 (1.5), P = 0.02], global rating scale [17.4 (4.4) vs 22 (2.1), P = 0.01], and ABPAS score [30 (9.8) and 39.6 (3.2), P = 0.01]. CONCLUSIONS: The ABPAS is a novel measurement tool which assesses technical surgical skill and can identify surgical competency in arch bar placement and dental wire handling. This tool may have future use in residency training and continuing education.

Acute assessment of brain injuries in ground-level falls.

OBJECTIVE: The purpose of this study was to characterize traumatic brain injuries (TBI) sustained in ground-level falls (GLFs). The focus was on factors associated with acute computed tomographic (CT) findings. METHODS: The sample included 575 subjects examined and treated at the Tampere University Hospital emergency department (ED). Retrospective data collection consisted of subject- and injury-related data and clinical information from the emergency department. All CT scans were analyzed and systematically coded. RESULTS: Ground-level falls were the mechanism of injury in 48.3% (n = 278) of the subjects. In the GLF group, independent risk factors for acute traumatic CT findings were long-term alcohol abuse, older age, being found on the ground, and left temporoparietal and occipital location of direct head impact. There were no significant differences in the incidence of any intracranial traumatic lesion type between those with GLFs and other causes of TBI. None of the classic clinical TBI severity markers studied were associated with acute traumatic CT findings in patients with GLFs. CONCLUSIONS: Older age and long-term alcohol abuse increase the likelihood of acute intracranial CT abnormalities. The pattern of intracranial traumatic CT findings does not differ from other causes of TBI. Clinical signs and indices of TBI severity did not predict traumatic CT findings.

Modified acrylic cranioplasty for large cranial defects.

OBJECTIVE: To describe a novel technique for constructing polymethylmethacrylate (acrylic) cranioplasty to repair large cranial defects. METHODS: A rim of bone is cut from the edge of the skull defect using a craniotome. This bony rim provides a scaffold to fashion the acrylic cement away from the patient thus avoiding thermal injury to the brain. The inner edge of the bony rim is drilled circumferencially to form a groove. Acrylic is then used to fill the defect in the bony rim with continuous manipulation of the paste from both sides to form a dome in the shape of the skull. The groove allows the edge of the acrylic dome to fit snugly with the bony rim thus avoiding sinking. The final cranioplasty, comprised of the hardened acrylic dome with the surrounding bone rim, is firmly attached to the skull with bioplates. RESULTS: We used the modified acrylic cranioplasty technique in three patients. Modified acrylic cranioplasty is cheaper and immediately available, compared with ten cases of titanium cranioplasty, with similar cosmetic outcome, intraoperative blood loss and operating theatre time. CONCLUSION: Our technique is quick and easy to perform, avoids thermal injury to the brain and produces a strong implant with excellent cosmesis even with large bony defects.

Experimental assessment of calvarial bone defect re-ossification stimulation using low-intensity pulsed ultrasound.

Ultrasound treatment has been proposed by several authors to enhance the repair of long bone injury. The present study investigated in a murine model the treatment by low-intensity pulsed ultrasound (LIPUS) of calvarial flat bone defect. The animals were operated to create bone defect and exposed to ultrasound for 5 min per day, 5 d per week, during two weeks. Two intensities of ultrasound (1 MHz, 100 Hz pulse repetition frequency and 20% duty cycle) were investigated: 100 and 300 mW/cm(2) spatial-averaged, time-averaged. Re-ossification surface and volume were determined after 30 and 60 days using computerized X-ray tomography in all animals of the control and treated groups. The results showed a significant increase of bone re-ossification in the group treated with the higher-intensity ultrasound (mean value of 18% volume reconstruction), whereas lower bone reconstruction was observed in the lower-intensity and control groups (respective mean values of 10 and 12% volume reconstruction).

Cranial trauma in iron age Samnite agriculturists, Alfedena, Italy: implications for biocultural and economic stress.

The Samnites are an Iron Age protohistoric people from the central region of Italy. The skeletal remains are from the Alfedena necropolis, 6th through 5th centuries B.C. Macchiarelli et al. (Antropologia Contemporanea 4 (1981) 239-243) were the first to report on cranial trauma for this population, presenting four cases with extreme injuries. We re-examined this well documented skeletal population for additional examples of trauma. Previously unexamined remains from Alfedena, excavated at the turn of the 20th century, are also included in our analysis (Mariani. 1901. "Aufidena", ricerche archeologiche e storiche del Sannio settentrionale. Roma: Acc Naz Dei Lincei). Of the 209 adult crania examined, 12.9% of them exhibited trauma. Analysis of location and frequency of cranial trauma revealed that cranial injuries to the head appear to originate from all directions. The high rate of cranial trauma underscores the violent circumstances experienced during the Iron Age protohistoric period of central Italy. Males are much more likely to exhibit cranial injury than females (P = 0.009). We conclude that the injuries received by Samnite male farmer-warriors occurred while defending pastoral-agricultural resources. Trauma rates are similar for some Iron Age populations and not for others. Behavior associated with violence during the Iron Age period can not be generalized for all populations found in Italy.

Assessment of the effect of a biphasic ceramic on bone response in a rat calvarial defect model.

Calcium phosphate ceramics are being extensively used for orthopedic, periodontal, and dental applications. This study aimed to assess the effect of a biphasic ceramic such as Ceraform on the osteogenesis in a rat calvarial defect model. 20 Wistar rats were enrolled in the study. Two symmetrical, circular, and 5-mm-wide full thickness defects were created in the parietal bones of each animal. The left defect was left empty as a control and the right defect was filled with the particular implant material. Animals were divided into two groups, and 10 animals were sacrificed at month 3 and the rest were sacrificed at month 6. The calvarial specimens were harvested for histological examinations. Defect area samples were stained with hematoxylin-eosin and Masson Thrichrom. A semiquantitative method was used to quantify the bone regeneration. The defects were mostly filled with fibrous connective tissue (3-6 months) in the control site. A loose, fibrovascular tissue was observed at the side of ceraform implantation at month 3. By 6 month, a dense collagenous tissue was observed at the same area. Multinuclear giant cells (MNGC) were detected around the implant bed at month 3 and month 6. No necrosis, tumorigenesis, or infection was observed at the implantation site at any time. There was no statistically meaningful difference regarding bone regeneration between the two defects at each observation period (p>0.05). This study showed that Ceraform is biocompatible. However, this study indicates that biphasic ceramic do not offer any advantage over hydroxyapatite ceramics. It was also revealed that it had no effects on bone regeneration and that it seemed to be a space maintainer.

Sensitivity of autopsy and radiological examination in detecting bone fractures in an animal model: implications for the assessment of fatal child physical abuse.

Skeletal injuries are often strong indicators of child abuse and their detection is therefore crucial. The aim of this study was to compare the sensitivity of three diagnostic approaches, namely autopsy, traditional (conventional) radiology, and computed tomography on "battered" piglets, in order to verify the sensitivity of each method, with respect to the true number of bone fractures assessed once the piglet was skeletonised (osteological control). Four newborn cadaver piglets who had died from natural causes were severely beaten post-mortem in every district of the body. Traditional radiography, computed tomography (CT) and autopsy were performed. The piglet was then macerated until skeletonised and the number of all fractures present recorded (osteological control). On the cranium, traditional radiology revealed only 35% circa of actual fractures, autopsy detected only 31% (P<0.01 for both comparisons versus osteological control), whereas CT imaging detected all fractures actually present. For ribs, radiology detected only 47% of all fractures present, and autopsy 65% circa (P>0.05 for both comparisons versus osteological control), while CT scans detected 34% (P<0.01). In suspected cases of fatal child abuse, we suggest that the bones of specific districts be directly analysed either at autopsy or by collecting specific diagnostic sites, such as parts of the rib cage, and subjecting them to maceration. The removed areas could be replaced with artificial material for cosmetic purposes. The authors stress the importance of combined radiological, CT scan, autopsy and osteological survey in the detection of perimortem bone fractures.

Morphological assessment of the behavior of three-dimensional anionic collagen matrices in bone regeneration in rats.

The osteogenic behavior of three-dimensional collagenic and anionic matrices (M3DGA) implanted in critical bone defects of 8 mm diameter was morphologically assessed. The defects were performed in the calvaria of 48 adult male (Wistar) rats, and observed at days 15, 30, and 60. The animals were distributed in four groups of equal number: GA1 (M3DGA with 60 min of cross-linking in glutaraldehyde [GA]); GA2 (M3DGA with 30 min of cross-linking in GA); GA3 (M3DGA with 15 min of cross-linking in GA); and G4 (control group, without any implanted biomaterial). The M3DGAs were biocompatible, with mild and regressive chronic granulomatous inflammation, associated with the degradation of their fibers. Furthermore, tissue neovascularization and neomineralization was noted, with statistically significant differences in these amounts among the groups (GA1, GA2, and GA3) and G4. In G4 neoformation was limited to the edges of the defect as well as interstitial fibrosis. Under the experimental conditions and for the parameters analyzed, the M3DGAs had osteogenic behavior, which was more evident in M3DGA 15 min.