Review on biomechanical mechanism of the hottest c

Summary of research on the biomechanical mechanism of craniocerebral impact injury

Abstract: in all kinds of injury accidents, the high incidence and high mortality of craniocerebral impact injury make the research on the biomechanics of craniocerebral impact injury become a research hotspot in the field of impact injury biomechanics. This paper reviews the historical development and latest progress of biomechanical research on craniocerebral impact injury, including experimental research, mechanical analysis model, injury mechanism and injury index. Finally, the problems to be discussed in the future are discussed

key words: biomechanics of head impact injury

review on the research of head impact injury biomechanics

ma Chunsheng, Huang Shilin, Zhang Jinhuan

state Key Laboratory of automotive safety and energy of Tsinghua University

[abstract] the research of head impact investment biology has be from Jinan gold testing machine come one focus in the domain of human impact biology because the high income and severity rate of head impact investment in all kings of accidents This paper reviewed the history and latest advances on the research of head impact injury biomechanics that included experimental research, mechanical analytical models, injury mechanism and injury criteria. In the end, the recommendations for future research are discussed.

key words: head impact injury biology

1 introduction

brain impact injury is one of the common injuries and the main causes of death in traffic accidents. According to foreign statistical data, the incidence of brain impact injury is as high as 54% [1], which is the primary cause of death and disability after injury. Head trauma accounts for about 34% of all human trauma, and 68% of trauma leading to death [2] (Gennarelli et al, 1992). In the United States, about 200000 cases of brain trauma occur every year [3] (Kraus and McArthur, 1996), and the treatment cost of brain trauma is as high as $9-10 billion. According to the statistical data of traffic accident injuries in a certain area of Sichuan, head injuries account for the highest proportion of injuries in all parts of the human body, which is 33.7%[4]. In view of this, the biomechanical research on craniocerebral impact injury has become a hot spot in the biomechanical research field of impact injury. The purpose of biomechanical research on brain impact injury is to understand the mechanical response of brain tissue to impact, determine the dose-effect relationship between brain injury and mechanical load, and then clarify the mechanism of brain injury, so as to provide a theoretical basis for the protection of brain injury and the formulation of injury indicators

at present, the research methods of impact injury biomechanics include experimental research, making physical models and establishing mechanical analysis models. Because the mechanism of brain impact injury in 2016 is complex, the scientific research method is to comprehensively study the experimental model, physical model and mathematical model at the same time, so as to draw reliable conclusions suitable for people. The pathological and physiological indexes of the experimental model and the structural response of the corresponding physical model are used for the input and verification of the mechanical analysis model, analyze the injury mechanism, and obtain the relevant injury indexes of the human body under certain impact conditions. This paper will summarize the biomechanical research of craniocerebral impact injury from the aspects of experimental research, mechanical analysis model, injury mechanism and injury index

2 experimental research

experimental research is the biomechanical basis and main means of impact injury. The models used for experimental research include human cadaver model, animal model and abiotic model. Cadavers have the same anatomical structure as living bodies. Fresh human cadavers are a good substitute for biomechanical research of impact injury. However, due to tissue degradation, there is a lack of direct observation of physiological or pathological reactions caused by impact on the body. Animal experiments are a useful supplement in these aspects. Animal experiments can achieve the injury level and study the dynamic change process of internal tissues and organs of the body. It is a better method to explore the injury mechanism. However, due to the great difference between animals and human body in physical characteristics, the quantitative results of animal experiments cannot be extended to human body. The abiotic model is mainly applicable to theoretical research, with good stability and avoiding individual differences of biomaterials [5]

2.1 human cadaver experiment

due to social, ethical and legal reasons, the acquisition of cadaver specimens is greatly limited, so the data of cadaver experiment is difficult to obtain. The earlier cadaver experiment on brain impact injury was conducted by Lissner et al. At Wayne State University in the United States from 1939 to 1965. The purpose of the experiment is to study the mechanical mechanism of brain oscillation, linear skull fracture and intracranial pressure. Through the experiment, the first tolerance curve wstc[6] about head injury was obtained

nahum used non embalmed cadavers to conduct head fore-and-aft and lateral impact, observed the transient changes of acceleration and intracranial pressure, and compared the response to impact with and without helmets [7]. The data of this cadaver experiment was later cited by many scholars to verify the effectiveness of the numerical model. Got, C. et al. Conducted 42 cases of head direct impact experiments with uncorrupted cadaver heads. The heads fell freely, and the impact areas were frontal bone, temporal parietal bone, frontal facial bone [8]. Nusholtz used an impact testing machine to impact the human cadaver head in the up-down and posterior anterior directions, and observed the movement of the head, changes in intracranial pressure and brain injury [9]

recently, Wayne State University conducted an experiment of blunt object impact on the occipital bone of human cadaver skull. Before the experiment, metal balls and thin-walled tubes were used to form a 2.3mm, 3.9mm long marker close to the density of the brain. During the impact, the markers were placed in the brain, and the impact course of the brain was photographed by a high-speed X-ray machine (250 frames/second). At the same time, micro markers are also installed in the skull, and the movement of markers in the brain relative to the skull can be obtained by analyzing the captured images. This is a new measurement method, which provides valuable original data for the study of damage mechanism and numerical simulation [10]

2.2 animal model

in 1940, Denny Brown conducted a head impact experiment on primates. The results showed that when the head was fixed, the probability of brain oscillation decreased, and it was proved that acceleration was an important part of the pathological characteristics of brain injury and brain oscillation [11]. Gurdjian, Lissner and others conducted experimental research on brain oscillation with dogs, cats and primates, and believed that brain oscillation may be caused by brain stem injury, which is mainly caused by the overall movement of the head, skull deformation and the relative movement of intracranial objects relative to the skull [12]

ommaya et al. Used rhesus monkeys, squirrel monkeys and chimpanzees for volatilization injury experiments and direct impact experiments, and believed that about 50% of brain damage was attributed to the rotation of the head [13]. However, Abel et al. Used the hyge device to generate rotational acceleration to study the brain injury of rhesus monkeys, and believed that the factor causing brain oscillation was not a simple angular acceleration, but a combination of linear acceleration and angular acceleration [14]. Hodgswon et al. Conducted impact experiments using the brain hemisphere model of fresh lemurs. The conclusion is that the occurrence of brain stem injury is not only related to head movement, but also related to the shear force caused by the extension of cerebrospinal cord [15]. Ono et al. Conducted a series of experiments with 63 monkeys. The results show that the occurrence of monkey brain oscillation has no significant correlation with the angular acceleration of the head, but has a high correlation with the linear acceleration of the head [16]

2.3 abiotic model

gurdjian used brittle lacquer method to study the stress distribution and strain of skull impacted by external force in the 1940s. Anzelius and guttinger represented the brain with a rigid spherical shell filled with inviscid fluid. In the field of traffic engineering in the United States, a lot of manpower has been invested in the development of head and neck physical models for more than a decade, and the most perfect model is the one made by Deng and goldsmith[17]. Jiao Dabin and others in China designed the skull model of bilinear viscoelastic solid spherical shell filled with linear viscous fluid in 1992 [18], and Jiang Yanping designed the photoelastic model of brain [19], as shown in Figure 1

Figure 1 photoelastic model simulates the stripes when impacted

3 mechanical analysis model

cadaver experiment can get the mechanical response and physiological and pathological indicators of the brain under impact conditions, but it is far from enough for us to understand the deep mechanism of brain injury, because the current means cannot measure the stress, strain and other microscopic changes of human tissue, It is very necessary to establish a mechanical analysis model to analyze the damage mechanism. Due to the complexity of brain structure, material and structure, it is difficult to simulate the biomechanical response of brain impact, which needs to be simplified. In the mechanical model of brain impact, the assumption of material properties has experienced the development process of assuming the skull as rigid, elastic and viscoelastic, and the brain tissue as inviscid liquid and viscoelastic medium. In terms of geometric shape, it experienced the process from two-dimensional to three-dimensional, from assuming the skull as a spherical shell, ellipsoidal shell to a solid model. Yang Yiqian and others made a detailed review on the early research of relatively simplified mechanical models [20], and this paper focuses on the research of finite element analysis models

3.1 two dimensional finite element model

shugar and katona (1975) established a two-dimensional finite element model of the central sagittal plane of the head, and the element types are shell element and fluid [21]. Khailil and Hubbard (1977) established an axisymmetric spherical shell model filled with liquid [22]. The model simulates the scalp, skull and brain. It is found that there is a pressure gradient near the impact point and a tension gradient near the opposite point

cheng et al. (1990) established a two-dimensional finite element model of the coronal plane of the brain to study Dai (diffuse axonal injury) [23]. The results of the model are compared with the experimental results of cadavers. The results show that the contact surface, geometry and brain distribution of skull and brain have a great influence on the response of brain under inertial load. Ruan et al. (1991) established a coronal plane strain model of the head to study the response of the head under lateral impact. The response of the model is in good agreement with the data of public cadaver experiments [24]. This study shows that the meninges have an important influence on the stress distribution in the brain

willinger et al. (1992) established a finite element analysis model of the sagittal plane of the head [25]. Based on the vibration mode of the model, the author believes that the overall vibration of the brain in the skull is the cause of hedge injury. Tetsuya et al. Established a two-dimensional model of the coronal section of the head to study the Dai injury mechanism [26]. The results show that rotational acceleration can cause Dai injury, and because of the influence of the head structure, direct linear acceleration impact can also cause Dai injury. Figure 2 shows the two-dimensional finite element model established by Tetsuya, which has the anatomical structure of the brain, including skull, brain and cerebrospinal fluid

Figure 2 two dimensional finite element model of brain established by Tetsuya et al.

3.2 three dimensional finite element model

in recent 30 years, scholars have established many three-dimensional finite element models of head with real geometric structure. Ward (1975) established a three-dimensional finite element model including brain, cerebellum, brain stem, ventricle and dura mater. However, the skull in the model is defined as a rigid body, and the influence of skull deformation on brain impact response cannot be estimated [27]. Ruan et al. (1994) have a three-dimensional model with detailed anatomical structure [28], including scalp, skull with three-layer structure, dura mater, spinal fluid, brain and sickle. Verify the force and intracranial pressure of brain under impact response using the data of cadaver experiment