UNIVERSIDADE ESTADUAL DE CAMPINAS
FACULDADE DE ODONTOLOGIA DE PIRACICABA
EDUARDO DARUGE NETO
PIRACICABA
2020
SIMULAÇÃO COMPUTACIONAL DO IMPACTO DE UMA
BOLA DE FUTEBOL EM UMA CABEÇA HUMANA PARA
AVALIAÇÃO DOS PADRÕES DE ESTRESSE E
DEFORMAÇÕES POR MEIO DO MÉTODO DOS
ELEMENTOS FINITOS
COMPUTATIONAL SIMULATION OF SOCCER BALL
IMPACT ON HUMAN HEAD TO EVALUATION OF THE
DEFORMATION AND STRESS PATTERNS USING FINITE
EDUARDO DARUGE NETO
SIMULAÇÃO COMPUTACIONAL DO IMPACTO DE UMA
BOLA DE FUTEBOL EM UMA CABEÇA HUMANA PARA
AVALIAÇÃO DOS PADRÕES DE ESTRESSE E
DEFORMAÇÕES POR MEIO DO MÉTODO DOS
ELEMENTOS FINITOS
COMPUTATIONAL SIMULATION OF SOCCER BALL IMPACT
ON HUMAN HEAD TO EVALUATION OF THE
DEFORMATION AND STRESS PATTERNS USING FINITE
ELEMENT METHOD
Dissertação apresentada à Faculdade de Odontologia de Piracicaba da Universidade Estadual de Campinas como parte dos requisitos exigidos para obtenção do título de Mestre em Biologia Buco-Dental, na Área de Odontologia Legal e Deontologia.
Dissertation presented to the Piracicaba Dental School of the University of Campinas in partial fulfillment of the requirements for the degree of Master in Forensic Dentistry area.
Orientadora: Profa. Dra. Ana Cláudia Rossi
ESTE EXEMPLAR CORRESPONDE À VERSÃO FINAL DA DISSERTAÇÃO DEFENDIDA PELO ALUNO EDUARDO DARUGE NETO E ORIENTADA PELA PROFA. DRA. ANA CLAUDIA ROSSI.
PIRACICABA
2020
Ficha catalográfica
Universidade Estadual de Campinas
Biblioteca da Faculdade de Odontologia de Piracicaba Marilene Girello - CRB 8/6159
Daruge Neto, Eduardo,
D257s DarSimulação computacional do impacto de uma bola de futebol em uma cabeça humana para avaliação dos padrões de estresse e deformações por meio do método dos elementos finitos / Eduardo Daruge Neto. – Piracicaba, SP : [s.n.], 2020.
DarOrientador: Ana Cláudia Rossi.
DarDissertação (mestrado) – Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba.
Dar1. Método dos elementos finitos. 2. Morfologia. 3. Cabeça. 4. Futebol. 5. Ferimentos e lesões. I. Rossi, Ana Cláudia, 1988-. II. Universidade Estadual de Campinas. Faculdade de Odontologia de Piracicaba. III. Título.
Informações para Biblioteca Digital
Título em outro idioma: Computational simulation of soccer ball impact on human head to
evaluation of the deformation and stress patterns using finite element method
Palavras-chave em inglês:
Finite element method Morphology
Head Soccer
Wounds and injuries
Área de concentração: Odontologia Legal e Deontologia(M) Titulação: Mestre em Biologia Buco-Dental
Banca examinadora:
Ana Cláudia Rossi [Orientador] Cristhiane Martins Schmidt Felippe Bevilacqua Prado
Data de defesa: 28-02-2020
Programa de Pós-Graduação: Biologia Buco-Dental Identificação e informações acadêmicas do(a) aluno(a)
- ORCID do autor: https://orcid.org/0000-0001-9900-8229 - Currículo Lattes do autor: http://lattes.cnpq.br/2693053301475549
AGRADECIMENTOS
Durante esses anos de mestrado, passei pela mais poderosa
transformação da vida pessoal de um homem – a paternidade. Portanto, em primeiro
lugar, demonstro meu amor e gratidão à minha mulher Alessandra Nietsche, que com
seu instinto materno, garante todos os melhores sentimentos aos nossos pequenos
Mel e Ben, mesmo nas maiores adversidades e em todas as minhas ausências.
Durante toda minha vida, tive – e ainda tenho – a melhor e mais poderosa
escola, chamada família. Agradeço a ela, que está sempre ao meu lado,
ensinando-me a valorizar a educação; respeitar e amar a todos, bem como a tudo que ensinando-me
proponho fazer. De todos, não posso deixar de lembrar do meu avô Eduardo Daruge
e nossas longas conversas antes dos almoços em casa; meus pais, Eduardo Daruge
Júnior e Maisa Perrini Daruge, que me deram e, ainda me dão a vida, com amor
incondicional; meu irmão, Fernando, meu melhor amigo e companheiro, desde meu
primeiro ano de vida e sua linda, acolhedora e amorosa família: Natália, Nicholas e
Théo;
Agradeço a minha orientadora, Professora Ana Cláudia Rossi, detentora de
imensurável conhecimento científico e da arte de ensinar, com determinação e
paciência. Ao professor Alexandre Rodrigues Freire, que incansável dedicou-se para
que este estudo alcançasse, com muita qualidade, o resultado que queríamos.
À Universidade Estadual de Campinas, na pessoa do Magnifico Reitor Prof.
Dr. Marcelo Knobel. À Faculdade de Odontologia de Piracicaba, na pessoa do Senhor
Diretor, Prof. Dr. Francisco Haiter Neto. À Coordenadoria de Pós-Graduação, na figura
da Senhora Coordenadora Prof.ª Dr.ª Karina Gonzalez Silvério Ruiz. À Equipe Técnica
da Coordenadoria de Pós-graduação nas pessoas de Érica A. Pinho Sinhoreti, Raquel
Q. Marcondes Cesar, Claudinéia Prata Pradella, Leandro Viganó e Ana Paula Carone,
agradeço pela paciência, atenção e disponibilidade. Aos servidores da biblioteca da
FOP-UNICAMP pela valiosa disponibilidade e atenção. Ao programa de
pós-graduação em Biologia Buco-Dental, na figura da coordenadora Prof.ª Dr.ª Ana Paula
de Souza.
E a todos aqueles que mesmo de forma direta e indireta colaboraram com
este estudo.
RESUMO
O futebol é o esporte mais popular mundialmente. A literatura nos indica que durante
um jogo de futebol, há uma grande incidência de lesões na região da cabeça, devido
ao ato, comumente empregado por jogadores de cabecear a bola. Ao cabecear a bola,
poderá haver concussões no encéfalo. Atletas com sucessivas concussões podem
passar a sofrer de síndrome pós-concussão. Devido ao já explicitado, se faz
importante analisar a força que a bola chega na cabeça no jogador e as forças
resultantes deste impacto, e para tal, se faz necessário a criação de um modelo
computacional tridimensional por meio da análise de elementos finitos, a fim de
conseguir dados consistentes sobre os estresses e deformações mecânicas nos
tecidos ósseo e encefálico. Objetivou-se simular, em ambiente computacional,
impactos de bola de futebol na cabeça humana por meio do método dos elementos
finitos. Foram obtidos modelos tridimensionais de elementos finitos de crânio humano
seco e bola de futebol. As geometrias do crânio e da bola de futebol foram importadas
para o software Ansys Academic Research v17.2 (Ansys Inc., Cannonsburg, EUA)
para realizar a simulação computacional do impacto da bola de futebol no crânio pelo
método dos elementos finitos. O estresse equivalente de von-Mises foi avaliado. O
efeito do impacto causou uma alta concentração de estresse na superfície do osso
frontal no primeiro contato da bola. Observou-se estresse médio a alto em torno da
região de impacto no osso frontal, com alta concentração no arco superciliar, osso
temporal e parte da base do crânio. O impacto causou alta concentração de estresse
na região de impacto (osso frontal) e esse alto estresse se dissipou em outras áreas
do crânio, principalmente no osso occipital.
Palavras-Chave: Método dos elementos finitos; Morfologia; Cabeça; Futebol;
Ferimentos e lesões.
ABSTRACT
Soccer game is the most popular sport worldwide. The literature indicates that during
a soccer game, there is a high incidence of injuries in the head region, due to the act,
commonly used by players to head the ball. When heading the ball, there may be
concussions in the brain. Athletes with successive concussions may suffer from
post-concussion syndrome. Due to what has already been explained, it is important to
analyze the force that the ball reaches the player's head and the forces resulting from
this impact, and for that, it is necessary to create a three-dimensional computational
model through finite element method, in order to obtain consistent data on mechanical
stresses and deformations in bone and brain tissues. The aim was to simulate, in a
computational environment, impacts of a soccer ball on the human head using the finite
element method. Three-dimensional finite element model of a dry skull and soccer ball
were obtained. The geometries of skull and soccer ball were imported into the software
Ansys Academic Research v17.2 (Ansys Inc., Cannonsburg, USA) to perform the
computer simulation of soccer ball impact in the skull by finite element method. The
equivalent von-Mises stress was evaluated. The effect of the impact caused a high
stress concentration on the frontal bone surface at the first contact of the ball. Medium
to high stress was observed around the impact region in the frontal bone, with high
concentration in the superciliary arch, temporal bone and part of the skull base. The
impact caused high stress concentration in the region of impact (frontal bone) and this
high stress dissipated to other areas of the skull, mainly occipital bone.
LISTA DE ABREVIATURAS E SIGLAS
CAD
-
Computer Aided Design
FEM
-
Finite Element Method
GPa
-
Gigapascal
MPa
-
Megapascal
NURBS
-
Non Uniform Rational B-Splines
Pb
-
Lead
q
-
Element quality
STL
-
Stereolithographic
SUMÁRIO
1 INTRODUÇÃO
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2 ARTIGO: COMPUTATIONAL SIMULATION OF SOCCER BALL-HEAD
IMPACT TO EVALUATION OF THE DEFORMATION AND STRESS PATTERNS
USING FINITE ELEMENT METHOD
13
3 CONCLUSÃO
25
REFERÊNCIAS *
26
ANEXO 1: Verificação de originalidade e prevenção de plágio
28
ANEXO 2: Certificação do Comitê de Ética
29
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1 INTRODUÇÃO
Lesões na cabeça devido à prática esportiva são comuns e podem ser
causas típicas de concussão de atletas de diferentes modalidades esportivas. Kraus
et al. (1996) afirmaram que 75% das lesões cerebrais no esporte são considerados
leves, mas algumas podem causar efeitos deletérios. Médicos do esporte devem
reconhecer as características clínicas e avaliar estes pacientes e os sinais que
auxiliem na gravidade da lesão e na decisão de voltar ao jogo (Kraus et al.,1996).
O futebol é um esporte muito popular, atraindo mais de 265 milhões de
participantes no mundo e lesões na cabeça são frequentes e requerem cuidados
médicos específicos para cada caso (Dvorak et al., 2000). É um tipo de esporte não
combatível, o contrário acontece com o boxe ou qualquer outro tipo de luta corporal,
onde as lesões não são acidentais (Hureibi e McLatchie, 2010).
Vários estudos relataram traumas específicos de futebol, incluindo dados
sobre traumatismo craniano (Meladière et al., 2001; Cerulli et al., 2002; Dvorak 2007;
Dvorak et al., 2011; Herrero et al., 2014; Junge e Dvorak, 2015; Koch et al., 2016),
mas nenhum especificamente sobre lesões no osso frontal por consequências do
esporte. Em contrapartida, nas práticas não esportivas a literatura nos indica que os
homens são mais propensos a fraturas no osso frontal devido ao maior envolvimento
em acidentes automobilísticos, violência, alcoolismo e uso de drogas (Rodriguez et
al., 2008).
O diagnóstico, o tratamento de lesões traumáticas leves e a recuperação
relacionados ao esporte, ganharam notoriedade como uma das principais causas de
saúde pública. Lesões na cabeça durante o jogo de futebol representam cerca de 13%
de todas as lesões futebolísticas, com concussões 20% das lesões na cabeça e 78%
das concussões no futebol estão relacionadas com contato acidental entre a cabeça
dos jogadores (Comstock et al., 2015).
Em atletas com sucessivas concussões é comum ocorrer a síndrome
pós-concussão (Macciocchi et al., 1996), onde alguns sintomas persistem por algum
tempo, como dor de cabeça, irritabilidade, tontura, falta de concentração, mudança de
personalidade e fadiga, mas se tem melhora entre seis a oito semanas (Binder, 1986).
Nenhum atleta deve voltar ao esporte com vulnerabilidade do cérebro, quando ainda
são apresentados sintomas devido ao trauma sofrido, caso isso ocorra, pode gerar
um quadro clínico grave, a síndrome do segundo impacto (Saunder e Harbaugh,
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1984). Alguns estudos mencionam que o ato de cabecear a bola repetidas vezes está
relacionado com a diminuição nos escores de teste de memória, planejamento e QI,
enquanto outros estudos não relatam diferenças nestes escores neurocognitivos
(Colins et al., 2003; Lovell et al., 2007), mas esta técnica está diretamente relacionada
com dores de cabeça, amnésia. A partir deste ponto, deve-se levar em consideração
o contato cabeça-bola, como um fato de lesão.
O método dos elementos finitos é um método numérico usado para simular
o comportamento de sólidos de acordo com determinadas condições aplicadas no
sistema usando um método de aproximação, e vem se tornando cada vez mais
popular pois consegue ser amplamente adotado em uma ampla variedade de
situações e investigações (Nagasao et al., 2010; Rossi et al., 2014; Costa et al., 2017).
Baseado nas evidências da literatura (Eirale et al., 2010; McKee et al.,
2014), este trabalho se propõe a estudar, utilizando os métodos dos elementos finitos,
as possíveis alterações mecânicas durante a cabeçada de um jogador de futebol na
bola, visto que a literatura é escassa sobre o tema e fraturas decorrentes do futebol
vem crescendo gradualmente devido à popularidade do esporte. Não há dúvida de
que os modelos computacionais são capazes de simular impactos e podem ser de
grande valia para os pesquisadores da área, que buscam entender melhor o que
acontece durante um impacto, sendo causador ou não de fraturas ou lesões cerebrais.
Há muita controvérsia sobre os efeitos de impactos repetidos na cabeça,
no que diz respeito tanto ao risco de lesão após sofrer uma concussão quanto aos
efeitos de repetidos impactos de baixo nível na cabeça, como da bola na cabeça. Essa
controvérsia permanece parcialmente devido a dificuldade em avaliar a gravidade da
concussão e aos efeitos desconhecidos dos impactos repetidos da cabeça para a bola
(Shewchenko et al., 2005).
Fraturas na região anterior frontal do crânio é cada vez mais comum devido
à grande popularidade mundial do futebol (Eirale et al., 2010). Atletas com sucessivas
concussões podem passar a sofrer de síndrome pós-concussão (McKee et al., 2014).
Baseado nestes dados, se faz importante analisar de maneira mais aprofundada a
força que a bola chega na cabeça no jogador e as forças resultantes deste impacto, e
para tal, se faz necessário a criação de um modelo computacional por meio do
métodos dos elementos finitos, para obtermos dados consistentes sobre os estresses
e deformações mecânicas no crânio humano.
12
A hipótese da presente pesquisa foi que o impacto da bola de futebol
simulado computacionalmente no crânio humano cause deformações mecânicas no
tecido ósseo. Desta forma, objetivou-se simular, em ambiente computacional,
impactos de bola de futebol na cabeça humana por meio do método dos elementos
finitos.
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2 ARTIGO
COMPUTATIONAL SIMULATION OF SOCCER BALL-HEAD IMPACT TO
EVALUATION OF THE DEFORMATION AND STRESS PATTERNS USING FINITE
ELEMENT METHOD*
*O artigo foi submetido para apreciação no periódico internacional: Injury Journal
(ANEXO 3)
ABSTRACT
Aim: to simulate impacts of a soccer ball on the human head using the finite element methods. Material and Methods: Three-dimensional finite element model of a dry skull and soccer ball were obtained. The geometries of skull and soccer ball were imported into the software Ansys Academic Research v17.2 (Ansys Inc., Cannonsburg, USA) to perform the computer simulation of soccer ball impact in the skull by finite element method. The equivalent von-Mises stress was evaluated. Results: The effect of the impact caused a high stress concentration on the frontal bone surface at the first contact of the ball. Medium to high stress was observed around the impact region in the frontal bone, with high concentration in the superciliary arch, temporal bone and part of the skull base Conclusion: The impact caused high stress concentration in the region of impact (frontal bone) and this high stress dissipated to other areas of the skull, mainly occipital bone.
Keywords: Finite element method; Morphology; Skull Biomechanics; Soccer game; Trauma.
INTRODUCTION
The head-ball technique is common and important during the soccer game and frequently used among players, as an offensive/defensive game method (Straume-Naesheim et al., 2005), being repeated several times, it is a possible injury mechanism in the head.
Frequently, soccer players suffer mild concussions with other players, either from high kicks or even when they hit the field during a match or head the ball, which could be an effect of brain abnormalities without harmful effects. Boden et al. (2006) found that the number of concussion incidence in players with objects other than the ball during the game is too low to say that brain injuries in these athletes are considered mild, Grade I traumas, characterized by concussions without amnesia.
Mckee et al. (2014) performed an analysis of the 30-year US National Registry of Sudden Death in Young Athletes from 1980 to 2009 found 1,827 deaths in athletes aged 21 years or younger (mean 16 ± 2 years; 90 % male) including 261 (14 %) due to trauma, most often to the head and neck. In soccer play game, the speed of impact of the ball contributes significantly to injuries and traumas. From a biomechanical point of view, injuries are the result of forces acting on a specific type of tissue. This impact can result in harmful forces acting on the brain and the skull, causing damage that can be focal or diffuse (Goldsmith and Plenkett, 2004), and yet the impact can lead to deformation of corresponding structures, through surface structures or even deeper (Adamec et al., 2013).
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Finite element method (FEM) is an effective assessment tool, based on computational modeling and three-dimensional images that investigates the biomechanics behavior of skull from tomographic images (Cattaneo et al., 2003). From a biomechanical point of view, any type of injury is the result of forces acting in certain areas and the use of finite elements comes to determine the distribution of stresses and strain resulting from forces applied in certain regions, being as realistic as the variables in which the model was based (Strait et al., 2005).
The hypothesis of this research was the impact of the soccer ball on the human skull causes mechanical stress in the bone structure, in which dissipate along the skull bones. Thus, the purpose was to simulate an impact of a soccer ball on the human skull using FEM.
MATERIALS AND METHODS
The Committee for Ethics of Research of the University of Campinas (CAAE number: 158223319.0.0000.5418) approved this study (ANEXO 2).
Image acquisition
A dry skull with morphology of the anatomical structures preserved, qualitative morphological characteristics typical of an adult male, without macroscopic visible bone pathologies was randomly chosen. Bone surface images of the human skull were acquired using computed tomography scans (GE HiSpeed NX/i CT scanner, General Electric, Denver, CO) at a 0.25-mm slice thickness.
Geometry construction
From CT images of a dry human skull, the software Mimics Academic Research v18 (Materialise, Leuven, Belgium) was used for bone structure segmentation. To perform the segmentation, the gray values threshold interval was selected according to the bone density. The whole bone structure voxels were marked and converted to a polygonal three-dimensional (3D) surface, which the detailed skull anatomy was preserved. The 3D surface of skull was exported as a virtual stereolithographic format (STL) and transferred to 3-Matic Academic Research v10 (Materialise, Leuven, Belgium), in which a mathematical optimization was performed (correction of surface intersections, noise shells and triangle overlapping) and, then, the 3D surface was converted to geometric model by reverse engineering (Figure 1).
The geometry of a soccer ball was constructed using the Rhinoceros v5 software (McNeel & Associates, Seattle, USA), whose components were organized in an inner ball layer and an outer ball layer. The skull geometry was imported into the software and, then, the ball was positioned to simulate an impact on the frontal bone (Figure 1).
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Figure 1. Geometry acquisition through reverse engineering, in which the STL model was converted into a CAD geometry (Computer Aided-Design). On the bottom the geometry of the skull and the soccer ball in the initial position.
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Figure 2. Finite element meshes showing the tetrahedral elements. The black arrow indicates the velocity direction and the red arrows indicate the region of restraint.
Analysis configuration
The geometries of skull and soccer ball were imported into the software Ansys Academic Research v17.2 (Ansys Inc., Cannonsburg, USA) to perform the computer simulation of soccer ball impact in the skull by FEM. The geometries were converted to a tetrahedral meshes (Figure 2) composed by 209,584 elements and 56,296 nodes. The models (skull and soccer ball) were assigned as linear elastic material properties (Table 1).
For the boundary conditions, the skull was considered in a static position and the nodes on the regions of neck muscles fixation as well as the atlanto-occipital joint were restrained in all axes. A velocity of 50 m/s was applied toward the frontal bone of the skull, to simulate a condition of a soccer ball hitting the skull in a full force strike (Babbs, 2001).
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Table 1. Properties of the materials used in the finite element models.
Properties Human Bone
a Soccer Ball (Inner layer) b Soccer Ball (Outer layer) b Young’s modulus (GPa) 14 0.35 0.7 Poisson’s ratio 0.3 0.475 0.475 Shear modulus (GPa) 5.3846 1.18 2.37
Bulk modulus (GPa) 11.667 2.33 4.66 Density (Kg/m3) 1850 1000 1000
Specific heat (J/Kg.uC) 440 434 434
a Wroe et al., (2010). b AnsysDatabase.
Analysis of Results
The equivalent von-Mises stress were calculated in a scale configured by Ansys v17.2 (Ansys Inc., Cannonsburg, USA). The equivalent von-Mises stress (MegaPascal - MPa), was evaluated to figure out the stress distribution and the energy dissipation along the bone structure of the skull. The total deformation was also evaluated the figure out the general direction pattern of bone deformation at the moment as well as after the impact.
RESULTS
The impact on the frontal bone from a soccer ball in high velocity (Figure 3) showed, at the moment of impact, the higher deformation of the neurocranium, mainly the frontal, parietal, temporal and part of occipital bones in backward direction (Figure 4A). Medium to high deformation occurred in the facial bones in an oblique direction (superiorly and posteriorly). The inferior part of occipital bone and the skull base showed lower deformation in oblique direction (inferiorly and posteriorly). The Figure 4B shows the reaction after the impact, which shows the deformations in medium to lower values as well as an anterior direction. To describe the stress distribution, the impact process was divided in initial, impact and final moments.
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Figure 3. Moment of the impact showing the deformation of the ball and the energy dissipation along the skull
Stress distribution at the initial moment
The effect of the impact caused a high stress concentration on the frontal bone surface at the first contact of the ball. Medium to high stress was observed around the impact region in the frontal bone, with high concentration in the superciliary arch, temporal bone and part of the skull base (Figure 5A). At this moment, the facial bones presented lower stress magnitude in general, however it can be observed high stress area in the floor of the nasal cavity.
Stress distribution during the impact moment
After the first contact the ball and during the impact (Figure 5B), a high stress was observed in the frontal, temporal, orbital cavity and region involving the mastoid part of temporal bone and the under surface of occipital bone. Medium to low stress was observed in the most part of parietal bone and facial bones. A high stress area can be observed in the inferior nasal concha.
Stress distribution during the final impact moment
On the impact region of frontal bone, the high stress area was decreased. Points of high stress was observed in the temporal bone, part of lateral margin of orbital aperture, maxilla and zygomatic bones. The higher stress area was observed in the mastoid region and most part of the occipital bone. The rest of the skull presented medium to low stress areas (Figure 5C).
After the impact the most part of the skull presented, in general, low stress distribution (Figure 6). However, high stress points were observed inside the orbital cavity, zygomatic arch and mastoid process.
In general, the stress distribution along the moments of the impact featured a high energy dissipated from the impact region toward the posterior and lateral bone structure of the skull.
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20
Figure 5. Equivalent von Mises stress distribution at the initial moment of the impact (A), at the moment of impact (B) and at the final moment of the impact (C)
DISCUSSION
In soccer sport, the ball can be directed deliberately and purposefully with the head (heading the ball). A series of studies suggested that brain atrophy upon CT scanning (Sortland and Tysvaer, 1989), electroencephalographic changes (Tysvaer et al., 1989), and subtle deficits in memory, concentration, planning, and alertness occur in long-time soccer players that can be related to the number of balls headed. To better understand the risk of heading a soccer ball, we created a finite element model of the skull and of the ball to describe the stress distribution of heading.
21
The results from Babbs (2001) suggested heading is usually safe but occasionally dangerous, depending on key characteristics of both the player and the ball. Safety is greatly improved when players head the ball with greater effective body mass, which is determined by a player’s size, strength, and technique. However, this author reports an accident situation when the soccer ball hit the head by a full force strike and, according to Boden et al. (1998), players may be caught unaware and therefore not react quickly enough to protect themselves. A full force strike has been shown in previous studies ranging 28 to 34 m/s (Asami and Nolte) and 27 to 54 m/s (Jordan et al., 1996). Thus, Babbs (2001) reported that a soccer ball impact with speed of up to 50 m/sec could be clearly concussive and dangerous. This present study showed an impact of 42 m/s velocity in the frontal bone, showing high stress concentration in different areas of the skull, mainly on the neurocranium. Thus, this simulation corroborates to the idea of the nervous system injury after a high-speed impact in the head.
To figure out the damage caused by ball impact in sports, the computational simulation approach has been subject in recent studies. Lee and Wang (2010) proposed a finite element model of a golf ball in a human head, where the patterns of stress and energy flow were evaluated from different velocities, angle of fall of the ball and impact locations. The authors found that a child is more prone to head injury due to golf ball impact on the frontal and side/temporal areas. Other effects have been observed in the skull as bone fracture (Katagiri et al., 2012, Li and Gao, 2017). These simulations presented a high stress concentration in specific areas; however, the author did not report the energy dissipation toward the other areas of the skull. This present showed the stress dissipation along the skull bones, which can be related to the greater mass of the soccer ball. Furthermore, the stress dissipation to different areas of skull can be related to secondary injuries in other structures, in this case we observed high stress in the occipital region, which is related to the neck structures.
This present study showed the impact of a soccer ball in the skull without soft structures. In addition, to simulate the atlanto-occipital joint, restraints were applied in the articular surface of occipital condyle. Moreover, the cervical muscles fixation was simulated by the application of restraints in their region of muscle origin. With these limitations, we cannot affirm that this specific case of high-speed soccer ball impact goes to cause brain or another soft tissue injury. However, the results corroborate with injury reports in the literature and, thus, can be a base for future studies to figure out the cause of nervous system diseases in soccer players.
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Figure 6. Equivalent von Mises stress after the ball impact.
CONCLUSION
This study showed the computer simulation by FEM of a high-speed impact of a ball soccer in the frontal bone. Considering the limitations of this study, the impact caused high stress concentration in the region of impact (frontal bone) and this high stress dissipated to other areas of the skull, mainly occipital bone.
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COMPLIANCE WITH ETHICAL STANDARDS
Disclosure of potential conflicts of interest No Funding
Conflicts of interests: The authors declare that they have no conflict of interest Research involving human participants
Ethical approval: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee (The Committee for Ethics of Research of the University of Campinas - CAAE number: 158223319.0.0000.5418) and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.”
Informed consent
Informed consent was not obtained, since the images from skull included in the study is in Anatomy Laboratory for decades. It was not possible to reach relatives as well.
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