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TDK conference 2008

Ex vivo breaking test of equine third metacarpal bones and proximal phalanges
Végh Zsófia - year 5
Large Animal Clinick, Üllő
Supervisor: Dr. Tóth Péter


The aim of our study is to give an answer to the question of the possibility of using densitometry to evaluate the risk of fracture not only in human medicine, but similarly in equine medicine. In human medicine, osteodensitometry by measuring the mass of mineral content is the basis of diagnosing calcipaenic osteopathies. The result of the measurement is the bone mineral density, BMD (g/cm2). The mineral content expressed in grammes is called the BMC, the bone mineral content (g).

We carried out BMD and BMC measurements of density of the third metacarpal bones and proximal phalanges of eight horses with DEXA (Dual Energy X-Ray Absorbtiometry) instrument from dorsopalmar direction. The third metacarpal bones and proximal phalanges of the left and right fore limbs were compared with paired t-test, from which no significant differences were found between the two sides. The BMD and BMC values of the third metacarpal bones and the proximal phalanges were also compared, and it was found that both the BMD and BMC values were significantly greater in case of the third metacarpal bone.

After the measurements of osteodensity and the bonemass, we tested the fragility of the matacarpal bones and proximal phalanges. The proximal phalanges were examined with CT before the breaking test and also after it. We defined certain morphological parameters of the proximal phalanges (the length of axes, cross-section area) and we examined the places of breaking gaps and fracture lines. Similarly to the data of our references, we carried out a three-point bending test on the third metacarpal bones. We tested the proximal phalanges with loading pressure. There is no information of the ex vivo fragility of bones similar to the proximal phalanges in the international reference source. Thus, we chose the method of loading pressure, because this is used for similar bones as the proximal phalanges (e.g. human lumbal vertebrae). We noted the holding power, the young module, the tensile strength and the bending strength of the bones, and we compared these data to osteodensity and bone mass with a linear regression analysis.

The holding power of the metacarpal bones was found to show significant correlation with BMD and BMC values, while in the proximal phalanges only the correlation with BMD values was found to be significant. Our results point to the possibility that osteodensitometry, which is applied nowadays routinely in human medicine, might be suitable to estimate the risk of bone fracture in horses. Further examinations with a larger sample number have to be done to prove our findings.

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