The Development and Validation of a Finite Element Human Thorax Model for Automotive Impact Injury Studies

Chang, Fred

doi:10.1115/imece2001/amd-25445

Cited by 6 publications

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“…To help determine the energy levels necessary required to produce orbit fracture, finite element (FE) analysis of orbital fracture from various impact energies was carried out using a human head FE model with detailed ocular anatomy. 8,9 The globe model included the cornea, sclera, aqueous humor, iris, lens, zonules, ciliary body, retina, and vitreous humor. The extraocular structures included 6 muscles, optic nerve, fat, and the orbit.…”

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Biomechanic Factors Associated With Orbital Floor Fractures

Patel

Andrecovich

Silverman

et al. 2017

JAMA Facial Plast Surg

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lowout fractures of the orbit, a term first put forth by Smith and Regan, 1 describes a specific set of fractures of the orbital bone often resulting from blunt trauma. Most commonly this refers to fractures of the orbital floor but can also include the medial orbital wall or the roof of the orbit. To further explain the mechanism underlying this type of fracture, the "buckling" theory and the "hydraulic" theory have been previously proposed. 2,3 The buckling theory contends that injury-but not fracture-to the infraorbital rim then leads to a fracture of the more delicate orbital floor. The hydraulic theory purports that insult to the globe itself transmits pressure to the orbital floor, thereby inducing a fracture. 4 However, in attempting to evaluate these theories, many previous studies have had inconsistences in their study design. For example, several studies 5,6 used fixed cadaveric skulls and failed to properly quantify the forces applied. Recent work by Ahmad et al 7 analyzed direct trauma to both the globe and rim in the orbits of fresh, intact, human postmortem cadavers using strain gauges in an attempt to test both the hydraulic and buckling mechanisms. Their experimental setup allowed for both qualitative and quantitative assessment of orbital floor fracture and demonstrated that the buckling mechanism tends to produce fractures in the anterior and anteromedial aspects of the orbital floor, whereas the hydraulic mechanism tends to produce fractures in the posterior aspects of the orbital floor. Our hypothesis is that both the hydraulic and buckling theories will manifest similar force thresholds required for fracture; however, anatomical fracture patterns will differ and can provide clinical data on the necessity of ophthalmologic evaluation. Methods The study was exempt from institutional review board approval because there were no HIPAA issues or human studies and only cadavers were used. A total of 10 orbits from 5 heads (3 male and 2 female) were used for this study. These came from IMPORTANCE Orbital floor fractures are commonly seen in clinical practice, yet the etiology underlying the mechanism of fracture is not well understood. Current research focuses on the buckling theory and hydraulic theory, which implicate trauma to the orbital rim and the globe, respectively. OBJECTIVE To elucidate and define the biomechanical factors involved in an orbital floor fracture. DESIGN, SETTING, AND PARTICIPANTS A total of 10 orbits from 5 heads (3 male and 2 female) were used for this study. These came from fresh, unfixed human postmortem cadavers that were each selected so that the cause of death did not interfere with the integrity of orbital walls. Using a drop tower with an accelerometer, we measured impact force on the globe and rim of cadaver heads affixed with strain gauges. RESULTS The mean impacts for rim and globe trauma were 3.9 J (95% CI, 3.4-4.3 J) and 3.9 J (95% CI, 3.5-4.3 J), respectively. Despite similar impact forces to the globe and rim, strain-gauge data displayed greater mean strain for...

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