Abstract of Thesis Presented to the Graduate School
                 of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science FORAMEN IS TOUGHER THAN DRILLED HOLE IN EQUINE THIRD METACARPUS

                                        By

                                  Barbara Garita

                                  December 2002
Chair: Dr. Andrew Rapoff
Department: Biomedical Engineering

       The purpose of this work was to compare the damage resistance and tolerance of bone in the vicinity of a natural hole, the nutrient foramen and a drilled hole in the equine third metacarpus. The nutrient foramen hole starts to form in early fetal stages, and the microstructure around it has been adapting to its presence since then. The indefinite adaptability is a reason why related studies have investigated the foramen and the microstructure around it. These studies have revealed that the microstructure reduces the local stress concentrations near the foramen, and that it increases structural strength. Also, elastic and strength manifestations of this microstructure were mimicked in the design and fabrication of a plate with a central hole. This plate demonstrated superior performance over a uniform plate with a hole. The present research deepens even more into the microstructure around the foramen and verifies that it also increases damage resistance and tolerance ("toughness") in response to cyclic loading. Also, osteon trajectories near the foramen were uncovered; they exist in regions of transverse tension