Mechanical properties of the cortical bone of the proximal phalanx in horses

The modulus of elasticity for the cortical bone in horses presented in the literature ranges between 1.75 and 20 GPa. The aim of the study was to determine the mechanical properties of the cortical bone of the proximal phalanx in horses in the three-point-bending test. Material and methods: The cortical bone was obtained from 10 horses (40 bones), both male and female, aged between 2-15 years. Bones were collected within 24 hours post mortem, dissected free of soft tissues, and then wrapped in plastic bags to prevent drying, and stored at -20 degrees Celsius. For the investigation, rectangular pieces of cortical bone were taken from the dorsal part of the bone. To determine the mechanical properties of the cortical bone the three-point-bending test was performed using the universal testing machine (Zwick 1435). All specimens were loaded with speed 2 mm/min to failure. During the testing procedure the following parameters were determined: maximum force, strength for bending, deformation for maximum force, modulus of elasticity and destroying work. Results and discussion: During investigation, the cortical bone from the dorsal part of the bone was exclusively tested because of its clear development. Mean values estimated during the tests were as follows: the modulus of elasticity 3.41GPa, maximum force (F-max) 605.32N, deformation for F-max 1.59 mm, strength for bending 110.61 MPa, destroying work 0.32Nm. Most of the bones used during the investigations were collected from horses of unknown breed killed in slaughter houses. Bones were collected only from healthy horses older than 2-years-of-age. Due to the lack of information about the breed, use of the horse and its feeding, determining the influence of these factors on the results was not possible. The dispersion of the results were significant and ranged for the elastic modulus between 1.37-6.66 GPa. An explanation for this can be the factor of using bones from different horses from different conditions like age, feeding, training, etc. Conclusions: Results of the elastic modulus achieved in our test are lower than the ones in horses and humans for long bones, which ranged between 16 and 20 GPa.