Third metacarpal condyle bone mineral density in relation to equine condylar fractures
Date
2004
Authors
Zimmerman, Chelsea A., author
Shearin, M. G., author
Kawcak, Chris E., author
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Abstract
Fractures of the third metacarpal condyle in metacarpophalangeal joints frequently occur in young racehorses during high-speed training or racing, and can be career or life ending. Prior research suggests that equine condylar fractures may occur from periods of continued loading, as opposed to a single traumatic event. Also, repeated trauma may lead to higher subchondral bone density, possibly reducing bone quality making it more susceptible to microfractures. The coalescence of these microfractures can lead to gross fracture. The objectives of this study were to evaluate density patterns within the distal third metacarpal (MC3) bone of forelimbs in racing and non-racing horses, and to determine how density patterns might relate to areas of condylar fracture commonly seen in racehorses. Computed Tomographic (CT) scans of the metacarpophalangeal joints were taken bilaterally on eight racehorses and eight control horses. Using OsteoApp, a program that utilizes CT data to create three-dimensional volumes, bone mineral density was measured from fifteen slices, taken in the frontal plane, radiating at 2mm increments from the palmar aspect to the dorsal aspect of the distal third metacarpus. A specific color scheme, based on CT pixel values, was established to identify visual patterns of the slices. Density data were then calibrated and analyzed using SAS software (Cary, NC). There was a statistically significant difference (p<.0005) between the mean densities of racehorses vs. control horses. Although there was no evidence that the limb (L, R) played a significant role, mean slice density of racehorses was significantly different between slice locations (p<.0001). In conclusion, racing and high speed training leads to a significant increase in density, and a density pattern that appears to create a sharp density gradient. Large changes in bone density are thought to increase the chances of fracture, therefore predisposing racehorses to injury. Further research is needed to identify the changes preceding a condylar fracture in order to prevent them.
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Subject
Horses -- Fractures
Bone densitometry