Interaction of hydraulic and buckling mechanisms in blowout fractures.
The etiology of blowout fractures is generally attributed to 2 mechanisms--increase in the pressure of the orbital contents (the hydraulic mechanism) and direct transmission of impacts on the orbital walls (the buckling mechanism). The present study aims to elucidate whether or not an interaction exists between these 2 mechanisms. We performed a simulation experiment using 10 Computer-Aided-Design skull models. We applied destructive energy to the orbits of the 10 models in 3 different ways. First, to simulate pure hydraulic mechanism, energy was applied solely on the internal walls of the orbit. Second, to simulate pure buckling mechanism, energy was applied solely on the inferior rim of the orbit. Third, to simulate the combined effect of the hydraulic and buckling mechanisms, energy was applied both on the internal wall of the orbit and inferior rim of the orbit. After applying the energy, we calculated the areas of the regions where fracture occurred in the models. Thereafter, we compared the areas among the 3 energy application patterns. When the hydraulic and buckling mechanisms work simultaneously, fracture occurs on wider areas of the orbital walls than when each of these mechanisms works separately. The hydraulic and buckling mechanisms interact, enhancing each other's effect. This information should be taken into consideration when we examine patients in whom blowout fracture is suspected.
Nagasao
Tomohisa
T
Department of Plastic and Reconstructive Surgery, School of Medicine, Keio University, Tokyo, Japan. nagasao@sc.itc.keio.ac.jp
Miyamoto
Junpei
J
Jiang
Hua
H
Tamaki
Tamotsu
T
Kaneko
Tsuyoshi
T
D001696:Biomechanical Phenomena; D003198:Computer Simulation; D006801:Humans; D009917:Orbital Fractures / Q000209:etiology* / Q000503:physiopathology*