TDK conference 2010

Stress fractures are considered to be one of the most significant economic losses in race industry. Microfractures tend to accumulate and are the sequelae of numerous factors during a horse’s life. Available non invasive methods for the evaulation of failure of strength of equine bone are limited. The objective of this study was to set the data gained from DXA (dual energy X-ray absorptiometry) and CT (computer tomography) examinations and compare to those obtained by loading pressure examination.

Sixteen proximal phalanxes of the thoracic limb were used after extraction from eight horses euthanized unrelated to a musculoskeletal injury. DXA was used to measure the whole bone mineral density (BMD), and additional three region of interests (ROIs) sites. Following evaluation of the bone density, whole bone, cortex width and cortical area in three different plane were measured using a CT. Finally bones were broken using a manually controlled universal bone crusher, a machine utilized in human research settings to measure bone failure strength.

Significant positive linear correlation was found between trabelcular BMD and the breaking strength (P=0,023, r=0,62). Other parameters did not significantly correlate with the breaking or compression force in this study.

The results of our experiment coincide with the common predilection site of the proximal phalanx fracture: the saggittal fracture, which is caused by the effect of the crista saggitalis of the third metacarpal bone. Based on this study, we can conclude that the trabecular site of the proximal phalanx also exhibits particular failure strength in an in vitro setting. These outcomes could be reassessed with a larger sample size to further reveal the predictive value of trabecular BMD in an in vitro biomechanical model with the presence of the third metacarpus, or an in vivo fracture risk model in the most affected population of horses.