A personalized finite element model for the study of boston brace correction in idiopathic scoliosis

Abstract

In an effort to delineate the tolerance of the human facial skeleton with respect to steering wheel impact, research was conducted using human cadavers. We reported the biodynamics of steering-wheel-induced facial trauma due to impacts at the unsupported rim (Yoganandan, Pintar & Sances, 1991). The present study was conducted to determine the probability of facial bone fracture secondary to impact at the spoke-rim junction. Either zygoma was impacted once onto the spoke-rim junction at velocities ranging from 1.4–6.9 ms. A six-axis load cell placed under the hub documented the generalized force histories. Interface force at the impact location was computed using the generalized force and deformation histories recorded at the spoke-rim junction using transformation principles. Bone mineral content was also determined. Facial pathology was evaluated using x-ray, two- and three-dimensional computed tomography, and defleshed skulls. Fractures of the zygoma, orbit, and maxilla were observed. While higher impact velocities resulted in propagation of fracture to the contralateral site, unilateral fractures of less severity occurred at lower speeds. Results indicated that a force level of 1525 N corresponds to 50% probability of facial fracture for the spoke-rim junction. Consequently, significant amelioration of facial injuries can be achieved if the forces are kept below this limit.