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1.
Clin Pediatr (Phila) ; 63(1): 135-145, 2024 01.
Artigo em Inglês | MEDLINE | ID: mdl-37212493

RESUMO

Reports of children's play-related injuries have remained stagnant according to epidemiology studies of the past 3 decades. This article provides a unique look into the context of playground injuries within an entire school district, demonstrating the prevalence of these injuries. This study reports that playgrounds are the leading location of school injury, comprising one-third of all elementary school injuries. This study found that while head/neck injuries were the most commonly injured body region within the playground environment, the proportion of head/neck injuries decreased with age, whereas the proportion of extremity injuries increased with age. At least 1 upper extremity injury required outside medical attention for every 4 that were treated on-site, making upper extremity injuries roughly twice as likely to require outside medical attention as injuries to other body regions. The data in this study are useful for interpreting injury patterns in the context and evaluation of existing safety standards for playgrounds.


Assuntos
Traumatismos do Braço , Lesões do Pescoço , Ferimentos e Lesões , Criança , Humanos , Jogos e Brinquedos , Traumatismos do Braço/epidemiologia , Parques Recreativos , Instituições Acadêmicas
2.
Am J Emerg Med ; 37(3): 427-432, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-29887192

RESUMO

PURPOSE: While generally reducing morbidity and mortality, TASER® electrical weapons have risks associated with their usage, including burn injuries and head and cervical trauma associated with uncontrolled falls. The primary non-fatal complications appear to be significant eye injury but no analysis of the mechanisms or suggested treatments has been published. METHODS: We used a biomechanical model to predict the risk of eye injury as a function of distance from the weapon muzzle to the eye. We compared our model results to recently published epidemiological findings. We also describe the typical presentation and suggest treatment options. RESULTS: The globe rupture model predicted that a globe rupture can be expected (50% risk) when the eye is within 6 m of the muzzle and decreases rapidly beyond that. This critical distance is 9 m for lens and retinal damage which is approximately the range of the most common probe cartridges. Beyond 9 m, hyphema is expected along with a perforation by the dart portion of the probe. Our prediction of globe rupture out to 6 m (out of a typical range of 9 m) is consistent with the published risk of enucleation or unilateral blindness being 69 ±â€¯18%, with an eye penetration. CONCLUSIONS: Significant eye injury is expected from a penetration by an electrical weapon probe at close range. The risk decreases rapidly at extended distances from the muzzle. Not all penetrating globe injuries from electrical weapon probes will result in blindness.


Assuntos
Lesões por Armas de Eletrochoque/patologia , Ferimentos Oculares Penetrantes/patologia , Adolescente , Adulto , Fenômenos Biomecânicos , Cegueira/etiologia , Cegueira/patologia , Enucleação Ocular , Ferimentos Oculares Penetrantes/etiologia , Feminino , Balística Forense , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Biológicos , Polícia/legislação & jurisprudência , Estados Unidos , Adulto Jovem
3.
J Forensic Leg Med ; 55: 52-57, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29462744

RESUMO

PURPOSE: While generally reducing morbidity and mortality, electrical weapons have risks associated with their usage, including burn injuries and trauma associated with uncontrolled fall impacts. However, the prevalence of significant eye injury has not been investigated. METHODS: We searched for incidents of penetrating eye injury from TASER® conducted electrical weapon (CEW) probes via open source media, litigation filings, and a survey of CEW law-enforcement master instructors. RESULTS: We report 20 previously-unpublished cases of penetrating eye injury from electrical weapon probes in law-enforcement field uses. Together with the 8 previously published cases, there are a total of 28 cases out of 3.44 million field uses, giving a demonstrated CEW field-use risk of penetrating eye injury of approximately 1:123 000. Confidence limits [85 000, 178 000] by Wilson score interval. There have been 18 cases of total unilateral blindness or enucleation. We also present legal decisions on this topic. CONCLUSIONS: The use of electrical weapons presents a rare but real risk of total or partial unilateral blindness from electrical weapon probes. Catastrophic eye injuries appear to be the dominant non-fatal complication of electronic control.


Assuntos
Lesões por Armas de Eletrochoque/epidemiologia , Ferimentos Oculares Penetrantes/epidemiologia , Adolescente , Adulto , Cegueira/epidemiologia , Cegueira/etiologia , Lesões por Armas de Eletrochoque/etiologia , Enucleação Ocular/estatística & dados numéricos , Ferimentos Oculares Penetrantes/etiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Polícia/legislação & jurisprudência , Prevalência , Adulto Jovem
4.
J Biomech Eng ; 133(3): 031002, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21303178

RESUMO

Eye trauma results in 30,000 cases of blindness each year in the United States and is the second leading cause of monocular visual impairment. Eye injury is caused by a wide variety of projectile impacts and loading scenarios with common sources of trauma being motor vehicle crashes, military operations, and sporting impacts. For the current study, 79 experimental eye impact tests in literature were computationally modeled to analyze global and localized responses of the eye to a variety of blunt projectile impacts. Simulations were run with eight different projectiles (airsoft pellets, baseball, air gun pellets commonly known as BBs, blunt impactor, paintball, aluminum, foam, and plastic rods) to characterize effects of the projectile size, mass, geometry, material properties, and velocity on eye response. This study presents a matched comparison of experimental test results and computational model outputs including stress, energy, and pressure used to evaluate risk of eye injury. In general, the computational results agreed with the experimental results. A receiver operating characteristic curve analysis was used to establish the stress and pressure thresholds that best discriminated for globe rupture in the matched experimental tests. Globe rupture is predicted by the computational simulations when the corneoscleral stress exceeds 17.21 MPa or the vitreous pressure exceeds 1.01 MPa. Peak stresses were located at the apex of the cornea, the limbus, or the equator depending on the type of projectile impacting the eye. A multivariate correlation analysis revealed that area-normalized kinetic energy was the best single predictor of peak stress and pressure. Additional incorporation of a relative size parameter that relates the projectile area to the area of the eye reduced stress response variability and may be of importance in eye injury prediction. The modeling efforts shed light on the injury response of the eye when subjected to a variety of blunt projectile impacts and further validate the eye model's ability to predict globe rupture. Results of this study are relevant to the design and regulation of safety systems and equipment to protect against eye injury.


Assuntos
Simulação por Computador , Traumatismos Oculares/fisiopatologia , Olho/fisiopatologia , Modelos Biológicos , Medição de Risco/métodos , Estresse Mecânico , Ferimentos não Penetrantes/fisiopatologia , Fenômenos Biomecânicos/fisiologia , Humanos , Estimulação Física/efeitos adversos , Estimulação Física/métodos , Curva ROC , Fatores de Risco , Ruptura/fisiopatologia
5.
Biomed Sci Instrum ; 46: 434-9, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20467119

RESUMO

Eye injuries remain a large societal problem in both the military and civilian sectors. Eye injury rates are increasing in recent military conflicts and there are over 1.9 million eye injuries in the United States civilian sector annually. In order to develop a better understanding of eye injury risk, several previous studies have developed eye injury criteria based on projectile characteristics. While these injury criteria have been used to estimate eye injury potential of blunt impact scenarios, they require that the mass, size and velocity of the projectile are known. It is desirable to develop a method to assess the severity of an eye impact in environments where it would be difficult or impossible to determine these projectile characteristics. The current study presents a measurement technique for monitoring intraocular pressure of the eye under impact. Through experimental tests with a custom pressure chamber, a subminiature pressure transducer was validated to be thermally stable and suitable for testing in an impact environment. Once validated, the transducer was utilized intraocularly, inserted through the optic nerve, to measure the pressure of the eye during blunt-projectile impacts. A total of 24 impact tests were performed using projectiles ranging from 6.3 mm to 9.5 mm in diameter. A correlation coefficient, R, of 0.95 indicates that intraocular pressure is correlated to the projectile mass-, size-, and velocity-based parameter of normalized energy. Further testing should be performed to better develop injury criteria based on intraocular pressure and to investigate the relationship between pressure- and projectile-based injury criteria. Intraocular pressure measurements also indicated a different response for perforating-type open-globe injuries with smaller diameter projectiles and scleral-rupture open-globe injuries with larger diameter projectiles. This indicates that intraocular pressure may lead to a better understanding of the transition between penetrating- and rupture-type injury mechanisms.

7.
Stapp Car Crash J ; 52: 379-420, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19085171

RESUMO

The purpose of this study was to investigate the influence of arm position on thoracic response and injury severity in side impacts. A total of sixteen non-destructive side impact tests and four destructive side impact tests were preformed using four human male cadavers. Single-axis strain gages were placed on the lateral and posterior regions of ribs three through eight on the impacted side, and the lateral region of ribs three through eight on the non-impacted side. Thoracic rods attached to ribs five, seven, and nine were used to measure lateral rib deflection. For the non-destructive tests, four test conditions with different arm positions were evaluated for each cadaver by performing displacement-controlled, low-energy, lateral impacts, 16 kg at 3 m/s, with a pneumatic impactor. The results of these tests showed that the highest average peak forces, peak rib deflections, and peak rib strains were observed when only the ribs were impacted and lowest when the shoulder was impacted. In addition, higher average peak forces, peak rib deflections, and rib strains were observed when the arm was placed parallel with the thorax versus 45 degrees. For the destructive tests, two test conditions were evaluated by performing high-energy lateral impacts, 23.4 kg at 12 m/s, with a pneumatic impactor. Only one destructive test was performed per cadaver with the arm placed at either 45 degrees or parallel with the thorax. Using rib fractures as the parameter for AIS, both tests conducted with the arm at 45 degrees resulted in an AIS = 4 due to the large number of ribs with multiple fractures which resulted in a flail chest. Conversely, both tests conducted with the arm parallel with the thorax resulted in an AIS=3. The analysis of thoracic strain gage time histories showed that, in general, the rib fracture timing varied with respect to thoracic region. Using scaled rib 5 deflection, lateral fractures on the impacted side occurred between 4.2 mm and 34.9 mm, posterior fractures on the impacted side occurred between 19.0 mm and 37.8 mm, and lateral fractures on the non-impacted side occurred between 60.2 mm and 74.3 mm of deflection. It was found that AIS = 1 injuries occurred at scaled rib deflections of 4.2 mm to 8.6 mm (2% to 3% compression), AIS = 2 at 9.6 to 17.4 mm (4% to 7% compression), and AIS = 3 at 13.1 mm to 20.1 mm (5% to 9% compression) measured at rib five. In conclusion, the results of the current study show that in low-energy side impacts both the arm and shoulder reduce impactor force, rib deflection, and rib strain. In high-energy side impacts, the position of the arm has a considerable effect on both the total number and distribution of rib fractures.


Assuntos
Acidentes de Trânsito , Braço/fisiologia , Fraturas das Costelas/fisiopatologia , Tórax/fisiologia , Fenômenos Biomecânicos , Cadáver , Tórax Fundido/etiologia , Humanos , Masculino , Pessoa de Meia-Idade , Postura/fisiologia , Ombro/fisiologia
8.
Biomed Sci Instrum ; 44: 243-8, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-19141923

RESUMO

Over 1200 paintball related eye injuries are treated every year in US emergency departments. These injuries can be manifested as irritation from paint splatter in the eye to catastrophic rupture of the globe. Using the Virginia Tech - Wake Forest University Eye Model, experimental paintball impacts were replicated and the experimental and computational results compared. A total of 10 paintball impacts were conducted from a range of 71.1 m/s to 112.5 m/s. All experimental tests resulted in rupture of the globe. The matched computational simulations also predicted near-failure or failure in each of the simulations, with a maximum principal stress of greater than 22.8 MPa in all scenarios, over 23 MPa for velocities above 73 m/s. Failure stress for the VT-WFU Eye Model is defined as 23 MPa. The current regulation velocity for paintballs of 91 m/s exceeds the tolerance of the eye to globe rupture and underscores the importance for eyewear in this sport.

9.
Biomed Sci Instrum ; 43: 7-12, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17487049

RESUMO

Over 2 million eye injuries occur each year in the United States as a result of trauma. In order to show the injury potential of objects such as BB guns, paintball guns, automotive airbag systems, and other consumer products, researchers have frequently tested enucleated eyes which have been placed in simulated orbits and held in place with a 10% gelatin solution. The purpose of this study is to perform biomechanical impact tests using both in-situ human eyes and human eyes mounted in simulated orbits, to compare the responses of both. A total of 12 dynamic eye impact tests were performed to develop force-deflection characteristics of the human eye in-situ, determine the effects that the extraocular muscles have on the response of the eye to dynamic impacts, and to characterize the force-deflection response of eyes supported with a gelatin solution within a simulated orbit. It was found that force-deflection corridors are similar with the extraocular muscles left intact or transected. Impact tests performed on eyes mounted in simulated orbits made of polycarbonate and filled with a 10% gelatin solution showed force-deflection responses that matched those of the in-situ eye impact tests. It is concluded that the use of simulated orbits to perform eye impact tests offers the appropriate boundary conditions to represent the in-situ human eye under dynamic eye impact events.


Assuntos
Fenômenos Biomecânicos/métodos , Enucleação Ocular , Traumatismos Oculares/fisiopatologia , Olho/fisiopatologia , Testes de Dureza/métodos , Estimulação Física/métodos , Ferimentos não Penetrantes/fisiopatologia , Cadáver , Elasticidade , Traumatismos Oculares/etiologia , Dureza , Testes de Dureza/instrumentação , Humanos , Técnicas In Vitro , Estimulação Física/efeitos adversos , Sensibilidade e Especificidade , Ferimentos não Penetrantes/etiologia
10.
Biomed Sci Instrum ; 43: 342-7, 2007.
Artigo em Inglês | MEDLINE | ID: mdl-17487105

RESUMO

Preventing cartilage injury is important in minimizing the long term debilitating effects of osteoarthritis. Accurate subfracture injury prediction must take into account the possible effects that freeze thaw cycles may have on the mechanical properties of cartilage tissue. This paper addresses this concern with matched pair testing of various low temperature storage techniques against fresh control groups. Ten matched pairs of bovine knees were used for testing, five pairs for a -20 degrees C slow freeze cycle and five pairs for a -80 degres C flash freeze cycle. Controlled mechanical indention tests were performed on the bovine articular cartilage-on-bone specimens to compare stiffness, peak stress, and loading energy of the cartilage. Findings showed that a slow freeze cycle or flash freeze cycle caused cartilage stiffness to decrease by 37% and 31% respectively, which was statistically significant in both cases (p< or =0.01). Compressive stress at this strain was also lowered by 31% with a slow freezing process (p=0.03). A similar trend was observed with compressive stress in the flash freeze specimens, although the 37% decrease was not found to be statistically significant (p=0.08). These results may be indicative of a weakened extracellular matrix structure caused by the freeze-thaw process. It is still unclear whether these changes in mechanical properties will result in a change in injury susceptibility for articular cartilage.


Assuntos
Cartilagem Articular/fisiologia , Congelamento , Modelos Biológicos , Animais , Fenômenos Biomecânicos/métodos , Bovinos , Simulação por Computador , Elasticidade , Estresse Mecânico , Viscosidade
11.
Stapp Car Crash J ; 51: 381-400, 2007 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-18278605

RESUMO

The Facial and Ocular CountermeasUre Safety (FOCUS) headform is intended to aid safety equipment design in order to reduce the risk of eye and facial injuries. The purpose of this paper is to present a three part study that details the development and validation of the FOCUS synthetic eye and orbit and the corresponding eye injury criteria. The synthetic eye and orbit were designed to simulate the force-deflection response to in-situ dynamic impacts. In part I, the force-deflection response of the eye was determined based on dynamic blunt impact tests with human eyes. These data were used to validate the appropriate material for a biofidelic synthetic eye. In part II, force-deflection corridors developed from ten dynamic in-situ eye impacts were used to validate the design and material selections for the synthetic orbit assembly. In part III, 82 experimental tests on the FOCUS headform were conducted using steel BB projectiles to develop a conservative injury risk criteria for the FOCUS headform based on the response of the eye load cell. Injury criterion for globe rupture is strongly correlated to the data from the FOCUS eye load cell (R(2) = 0.995). Based on the response of the FOCUS eye load cell, a 50% risk of globe rupture from a 4.5 mm BB impact is shown to be 107 N. With a biofidelic synthetic eye and this projectile-specific injury criteria, the FOCUS headform can be used to conservatively evaluate the risk of globe rupture from > or = 4.5 mm diameter projectile impacts to the eye.


Assuntos
Traumatismos Oculares/etiologia , Modelos Biológicos , Ferimentos não Penetrantes/etiologia , Traumatismos Oculares/fisiopatologia , Olho Artificial , Humanos , Manequins , Fatores de Risco , Ruptura/etiologia , Ferimentos não Penetrantes/fisiopatologia
12.
Biomed Sci Instrum ; 42: 7-12, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16817577

RESUMO

Over 2.4 million eye injuries occur each year in the United States as a result of trauma. New toy guns, commonly referred to as Airsoft guns are increasingly becoming responsible for ocular injuries in children. The purpose of this study was to determine the ocular injury risk of these Airsoft guns by experimental testing and the use of previously generated ocular injury risk functions. A total of 26 Airsoft pellet impact tests were performed on both post-mortem human and porcine eyes in a laboratory environment. Projectile parameters of diameter, mass, and velocity were used to calculate the injury potential of these impacts for five different ocular injuries: corneal abrasion, lens dislocation, hyphema, retinal damage, and globe rupture. Globe rupture was not observed in any of the experimental tests, which is consistent with that reported in the literature. The two most likely ocular injuries caused by these Airsoft guns are corneal abrasion and hyphema, at nearly a 100% and a greater than 75% risk of injury, respectively. This is consistent with the types of injuries reported in the literature, with corneal abrasion and hyphema being the most frequently occurring ocular injuries due to Airsoft guns. More experimental data on retinal injuries is necessary to make an accurate assessment of the risk of retinal damage from blunt impacts. In summary, the potential for ocular injury from Airsoft guns is great and protective equipment such as protective eyewear should be considered mandatory during operation.


Assuntos
Traumatismos Oculares/etiologia , Traumatismos Oculares/patologia , Armas de Fogo , Modelos de Riscos Proporcionais , Medição de Risco/métodos , Ferimentos por Arma de Fogo/etiologia , Ferimentos por Arma de Fogo/patologia , Animais , Humanos , Técnicas In Vitro , Fatores de Risco , Suínos
13.
Biomed Sci Instrum ; 42: 372-7, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16817636

RESUMO

More than 30,000 people lose sight in at least one eye every year in the United States. Globe rupture is one of the most severe injuries and can often result in the loss of an eye. Previous studies to determine the injury tolerance of the human eye to globe rupture have not investigated the effects of extraocular muscles on the response of the eye. The purpose of the current study is to quantify the effects of the extraocular muscles using quasistatic displacement tests of the human eye in situ. A total of three post-mortem human heads were used for the matched pair tests designed to elucidate any differences in the force-deflection response of the human eye with the extraocular muscles intact and transected. Computed tomography imaging was utilized to observe the deformation of the eye within the orbit for each displacement, from 0 mm to 30 mm. Slight differences in the force-deflection response are observed; however, it is not clear how these differences will influence impact response at a dynamic rate. It was also observed that under quasistatic displacements that the eye is able to translate out of the way of the impactor assembly, even under large deflections, and without globe rupture. Additional dynamic tests are recommended to determine the effects of the extraocular muscles on eye impact response.


Assuntos
Traumatismos Oculares/fisiopatologia , Movimentos Oculares , Músculos Oculomotores/fisiopatologia , Estimulação Física/efeitos adversos , Estimulação Física/métodos , Ferimentos não Penetrantes/etiologia , Ferimentos não Penetrantes/fisiopatologia , Cadáver , Humanos , Técnicas In Vitro , Medição de Risco/métodos , Fatores de Risco , Estresse Mecânico
14.
Aviat Space Environ Med ; 77(5): 509-14, 2006 May.
Artigo em Inglês | MEDLINE | ID: mdl-16708531

RESUMO

BACKGROUND: Technological advances in military equipment have resulted in more devices being mounted on the helmet to enhance the capability of the soldier. The soldier's neck must bear this head-supported mass (HSM) and the resulting dynamic characteristics of the head and neck system are changed. The purpose of this study was to vary the conditions of impact as well as the design criteria to quantify the effect of HSM on neck injury risk through computational modeling. METHODS: The TNO MADYMO detailed neck model was used for a matrix of 196 simulations designed to vary the impact conditions and HSM properties added to the model. These parameters included seven impact directions, three impact magnitudes, nine mass locations, and three mass magnitudes. The data collected from these simulations were evaluated for injury risk using the lower neck beam criterion equation. RESULTS: The results from these simulations provide detailed information regarding the risk of injury based on a particular HSM configuration and the acceleration of the body. The predominant factor in increasing risk in the lower neck is the increase in pulse magnitude. The effect of pulse magnitude is more dominant in the directions that create a flexion or lateral bending moment. CONCLUSION: HSM increases the level of injury, but the impact level that the subject is exposed to is a more dominating factor in determining injury risk.


Assuntos
Simulação por Computador , Cabeça/fisiologia , Modelos Biológicos , Lesões do Pescoço/fisiopatologia , Pescoço/fisiologia , Medicina Aeroespacial , Dispositivos de Proteção da Cabeça , Humanos , Medicina Militar , Suporte de Carga/fisiologia
15.
Stapp Car Crash J ; 50: 651-71, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17311182

RESUMO

Eye ruptures are among the most devastating eye injuries and can occur in automobile crashes, sporting impacts, and military events, where blunt projectile impacts to the eye can be encountered. The purpose of this study was to develop injury risk functions for globe rupture of both human and porcine eyes from blunt projectile impacts. This study was completed in two parts by combining published eye experiments with new test data. In the first part, data from 57 eye impact tests that were reported in the literature were analyzed. Projectile characteristics such as mass, cross-sectional area, and velocity, as well as injury outcome were noted for all tests. Data were sorted by species type and areas were identified where a paucity of data existed, based on the kinetic and normalized energy of assaulting objects. For the second part, a total of 126 projectile tests were performed on human and porcine eyes. Projectiles used for these tests included blunt aluminum projectiles, BBs, foam pellets, Airsoft pellets, and paintballs. Data for each projectile were recorded prior to testing and high-speed video was used to determine projectile velocity prior to striking the eye. In part three the data were pooled for a total of 183 eye impact tests, 83 human and 100 porcine, and were analyzed to develop the injury risk criteria. Binary logistic regression was used to develop injury risk functions based on kinetic and normalized energy. Probit analysis was used to estimate confidence intervals for the injury risk functions. Porcine eyes were found to be significantly stronger than human eyes in resisting globe rupture (p=0.01). For porcine eyes a 50% risk of globe rupture was found to be 71,145 J/m2, with a confidence interval of 63,245 J/m2 to 80,390 J/m2. Human eyes were found to have a 50% risk of globe rupture at a lower, 35,519 J/m2, with confidence intervals of 32,018 J/m2 to 40,641 J/m2. The results presented in this paper are useful in estimating the risk of globe rupture when projectile parameters are known, or can be used to validate computational eye models.


Assuntos
Traumatismos Oculares/etiologia , Traumatismos Oculares/fisiopatologia , Olho/fisiopatologia , Modelos Biológicos , Estimulação Física/efeitos adversos , Estimulação Física/métodos , Medição de Risco/métodos , Ferimentos não Penetrantes/etiologia , Ferimentos não Penetrantes/fisiopatologia , Animais , Simulação por Computador , Humanos , Fatores de Risco , Ruptura/etiologia , Ruptura/fisiopatologia , Especificidade da Espécie , Suínos
16.
J Trauma ; 59(4): 960-4, 2005 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-16374288

RESUMO

BACKGROUND: Eye injuries affect a large proportion of the population and are expensive to treat. This article presents a parametric analysis of experimental data to determine the most significant factors for predicting ocular injuries or tissue lesions. METHODS: Using logistic regression, statistical values were generated to determine significant projectile characteristics for predicting ocular injury in published studies. Projectiles included BBs, metal rods, and foam particles with velocities ranging from 2 m/s to 122 m/s. RESULTS: A normalized energy (energy per projected area) value was found as the best predictor for ocular injury. Using this predictor, a 50% injury risk of corneal abrasion, lens dislocation, hyphema, retinal damage, and globe rupture was found to be 1,503 kg/s(2), 19,194 kg/s(2), 20,188 kg/s(2), 30,351 kg/s(2), and 23,771 kg/s(2), respectively. CONCLUSION: Normalized energy was the most significant predictor of injury type and tissue lesion. This finding is of great value for history-taking management triaging and as a design aid to minimize the risk of ocular injury for consumer products.


Assuntos
Traumatismos Oculares/etiologia , Balística Forense/métodos , Intervalos de Confiança , Traumatismos Oculares/fisiopatologia , Humanos , Fatores de Risco
17.
Stapp Car Crash J ; 49: 199-230, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17096275

RESUMO

The purpose of this study was to develop material properties of human rib cortical bone using dynamic tension coupon testing. This study presents 117 human rib cortical bone coupon tests from six cadavers, three male and three female, ranging in age from 18 to 67 years old. The rib sections were taken from the anterior, lateral, and posterior regions on ribs 1 through 12 of each cadaver's rib cage. The cortical bone was isolated from each rib section with a low speed diamond saw, and milled into dog bone shaped tension coupons using a small computer numerical control machine. A high-rate servo-hydraulic Material Testing System equipped with a custom slack adaptor, to provide constant strain rates, was used to apply tension loads to failure at an average rate of 0.5 strains/sec. The elastic modulus, yield stress, yield strain, ultimate stress, ultimate strain, and strain energy density were determined from the resulting stress versus strain curves. The overall average of all cadaver data gives an elastic modulus of 13.9 GPa, a yield stress of 93.9 MPa, a yield strain of 0.88 %, an ultimate stress of 124.2 MPa, an ultimate strain of 2.7 %, and a strain energy density of 250.1 MPa-microstrain. For all cadavers, the plastic region of the stress versus strain curves was substantial and contributed approximately 60 % to the strain energy and over 80 % in the tests with the 18 year old cadaver. The rib cortical bone becomes more brittle with increasing age, shown by an increase in the modulus (p < 0.01) and a decrease in peak strain (p < 0.01). In contrast to previous three-bending tests on whole rib and rib cortical bone coupons, there were no significant differences in material properties with respect to rib region or rib level. When these results are considered in conjunction with the previous three-point bending tests, there is regional variation in the structural response of the human rib cage, but this variation appears to be primarily a result of changes in the local geometry of each rib while the material properties remain nearly constant within an individual.

18.
Artigo em Inglês | MEDLINE | ID: mdl-15319124

RESUMO

The purpose of this paper is to determine the static and dynamic rupture pressures of 20 human and 20 porcine eyes. This study found the static test results show an average rupture pressure for porcine eyes of 1.00 +/- 0.18 MPa while the average rupture pressure for human eyes was 0.36 +/- 0.20 MPa. For dynamic loading, the average porcine rupture pressure was 1.64 +/- 0.32 MPa, and the average rupture pressure for human eyes was 0.91 +/- 0.29 MPa. Significant differences are found between average rupture pressures from all four groups of tests (p = 0.01). A risk function has been developed and predicts a 50% risk of globe rupture at 1.02 MPa, 1.66 MPa, 0.35 MPa, and 0.90 MPa internal pressure for porcine static, porcine dynamic, human static, and human dynamic loading conditions, respectively.


Assuntos
Acidentes de Trânsito , Traumatismos Oculares/fisiopatologia , Idoso , Idoso de 80 Anos ou mais , Animais , Fenômenos Biomecânicos , Elasticidade , Humanos , Pressão , Ruptura , Suínos
19.
Stapp Car Crash J ; 48: 27-51, 2004 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17230260

RESUMO

The purpose of this study was to develop injury risk functions for dynamic bending of the human femur in the lateral-to-medial and posterior-to-anterior loading directions. A total of 45 experiments were performed on human cadaver femurs using a dynamic three-point drop test setup. An impactor of 9.8 kg was dropped from 2.2 m for an impact velocity of 5 m/s. Five-axis load cells measured the impactor and support loads, while an in situ strain gage measured the failure strain and subsequent strain rate. All 45 tests resulted in mid-shaft femur fractures with comminuted wedge and oblique fractures as the most common fracture patterns. In the lateral-to-medial bending tests the reaction loads were 4180 +/- 764 N, and the impactor loads were 4780 +/- 792 N. In the posterior-to-anterior bending tests the reaction loads were 3780 +/- 930 N, and the impactor loads were 4310 +/- 1040 N. The difference between the sum of the reaction forces and the applied load is due to inertial effects. The reaction loads were used to estimate the mid-shaft bending moments at failure since there was insufficient data to include the inertial effects in the calculations. The resulting moments are conservative estimates (lower bounds) of the mid-shaft bending moments at failure and are appropriate for use in the assessment of knee restraints and pedestrian impacts with ATD measurements. Regression analysis was used to identify significant parameters, and parametric survival analysis was used to estimate risk functions. Femur cross-sectional area, area moment of inertia (I), maximum distance to the neutral axis (c), I/c, occupant gender, and occupant mass are shown to be significant predictors of fracture tolerance, while no significant difference is shown for loading direction, bone mineral density, leg aspect and age. Risk functions are presented for femur cross-sectional area and I/c as they offer the highest correlation to peak bending moment. The risk function that utilizes the most highly correlated (R2 = 0.82) and significant (p = 0.0001) variable, cross-sectional area, predicts a 50 percent risk of femur fracture of 240 Nm, 395 Nm, and 562 Nm for equivalent cross-sectional area of the 5(th) percentile female, 50(th) percentile male, and 95(th) percentile male respectively.

20.
Stapp Car Crash J ; 48: 155-76, 2004 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17230265

RESUMO

This paper describes a three part analysis to characterize the interaction between the female upper extremity and a helicopter cockpit side airbag system and to develop dynamic hyperextension injury criteria for the female elbow joint. Part I involved a series of 10 experiments with an original Army Black Hawk helicopter side airbag. A 5(th) percentile female Hybrid III instrumented upper extremity was used to demonstrate side airbag upper extremity loading. Two out of the 10 tests resulted in high elbow bending moments of 128 Nm and 144 Nm. Part II included dynamic hyperextension tests on 24 female cadaver elbow joints. The energy source was a drop tower utilizing a three-point bending configuration to apply elbow bending moments matching the previously conducted side airbag tests. Post-test necropsy showed that 16 of the 24 elbow joint tests resulted in injuries. Injury severity ranged from minor cartilage damage to more moderate joint dislocations and severe transverse fractures of the distal humerus. Peak elbow bending moments ranged from 42.4 Nm to 146.3 Nm. Peak bending moment proved to be a significant indicator of any elbow injury (p = 0.02) as well as elbow joint dislocation (p = 0.01). Logistic regression analyses were used to develop single and multiple variate injury risk functions. Using peak moment data for the entire test population, a 50% risk of obtaining any elbow injury was found at 56 Nm while a 50% risk of sustaining an elbow joint dislocation was found at 93 Nm for the female population. These results indicate that the peak elbow bending moments achieved in Part I are associated with a greater than 90% risk for elbow injury. Subsequently, the airbag was re-designed in an effort to mitigate this as well as the other upper extremity injury risks. Part III assessed the redesigned side airbag module to ensure injury risks had been reduced prior to implementing the new system. To facilitate this, 12 redesigned side airbag deployments were conducted using the same procedures as Part I. Results indicate that the re-designed side airbag has effectively mitigated elbow injury risks induced by the original side airbag design. It is anticipated that this study will provide researchers with additional injury criteria for assessing upper extremity injury risk caused by both military and automotive side airbag deployments.

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