title: Determining bruise etiology in muscle tissue using finite element analysis.
abstract: Bruising, the result of capillary failure, is a common physical exam finding due to blunt trauma and, depending on location and severity, a potential indicator of abuse. Despite its clinical relevance, few studies have investigated the etiology of capillary failure. The goal of this study was to determine whether capillaries primarily fail under shear stress or hydraulic-induced tensile stress. An arteriole bifurcating into four capillaries was modeled using ANSYS 14.0 (®) . The capillaries were embedded in muscle tissue and a pressure of 20.4 kPa was applied. Any tensile stress exceeding 8.4 × 10(4)  Pa was considered failure. Results showed that failure occurred directly under the impact zone and where capillaries bifurcated, rather than along the line of greatest shear stress, indicating that internal tensile stress is likely the primary mode of capillary failure in bruising. These results are supported by the concept that bruising can occur via blunt trauma in which no shearing lacerations occur.
authors: Biomechanics Laboratory, Deerfield Academy, 7 Boyden Lane Deerfield, Deerfield, MA 01342.
authors: Kevin
authors: K
authors: Tang
authors: Wyatt
authors: W
authors: Sharpe
authors: Alexandra
authors: A
authors: Schulz
authors: Edric
authors: E
authors: Tam
authors: Ian
authors: I
authors: Grosse
authors: John
authors: J
authors: Tis
authors: Dennis
authors: D
authors: Cullinane
mesh_terms: D055592:Biophysical Phenomena / Q000502:physiology; D002196:Capillaries / Q000502:physiology; D003198:Computer Simulation; D003288:Contusions / Q000209:etiology* / Q000503:physiopathology; D020342:Finite Element Analysis; D006801:Humans; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000098:blood supply / Q000293:injuries*; D013314:Stress, Mechanical
keywords: bruising; capillary failure; finite element analysis; forensic science; hydraulic tensile stress; shear stress