Meeting Abstract

33.3  Tuesday, Jan. 5  How accurately does finite element analysis reproduce strain in the ostrich mandible during simulated pecking behavior? RAYFIELD, EJ; University of Bristol e.rayfield@bristol.ac.uk

Using finite element analysis (FEA) to model the musculoskeletal behavior of animals poses particular challenges, such as determining appropriate elastic properties, loading conditions, and capturing relevant geometry. In order to assess how accurately FEA can represent actual bone strain, a study was conducted to compare experimentally derived strain to FE-derived strain in the mandible of extant ostriches. A peak pecking force of 39 newtons (N) was recorded in live ostriches. Dissected ostrich mandibles were clamped at the condyles and loaded at the beak tip with 50 N of force in a hydraulic testing machine. Strains were recorded using gauges at four locations: lateral surangular, medial surangular, dorsal and ventral dentary. Strains were consistently highest in the ventral dentary, and lowest in the lateral surangular. Specimen-specific FE-models were created from CT data, and loaded identically. Models were isotropic and homogenous. Despite this inaccuracy, similarity was achieved between experimental and FE-derived strain. Patterns, orientation and peak strain locations were consistent with experimental data. Comparable magnitudes could be achieved by modifying Young’s modulus in the FE-model. Gauges bonded to the dentaries were more accurate than postdentary gauges. This may be due to intramandibular sutures modulating the bending behavior of the mandible, or increased cancellous bone in the posterior jaw (neither which were modeled at this stage using FE). This study implies that FE-models, even with simple material properties, may have the potential to reproduce reliable patterns of strain. These models may be informative in comparative and hypothetical studies, but one must be sure of functional loads, material properties and the effect of sutures and cancellous tissue in order to comment on absolute strains.