Novel computed tomographic analysis demonstrates differences in patterns of bone mineral content between fracture configurations in distal condylar fractures of the third metacarpal/metatarsal bones in 97 Thoroughbred racehorses

OBJECTIVE To evaluate bone mineral content patterns between fracture configurations using novel CT image analysis. ANIMALS CT images from 97 Thoroughbred racehorses with third metacarpal/tarsal condyle fractures provide the case population for analysis. PROCEDURES Fractures were grouped by radiographic appearance. Image analysis objectively measured area of highly attenuating pixels (aHAP), areal density of highly attenuating pixels (dHAP) utilizing novel convex hull analysis, and subjective assessment of apparent attenuation intensity ranking (AAIR) for each fracture. Differences between fracture configuration groups were evaluated. RESULTS Analysis of dHAP identified lower-density regions of highly attenuating pixels in propagating fractures and higherdensity regions of highly attenuating pixels in unicortical fractures (P =.028). Complete and incomplete configurations were almost indistinguishable in dHAP (P = 1.000). The ratio of dHAP between fractured and nonfractured condyles revealed higher density gradients between condyles in unicortical (P =.040) and incomplete (P =.031) fractures than propagating fractures. CLINICAL RELEVANCE Differences in patterns of bone mineral content were identified between propagating, bicortical (incomplete and complete), and unicortical fractures of third metacarpal/tarsal bone condyles. Computer-assisted geometric measurement of dHAP identified on CT images could help to assess fracture risk in equine athletes. This application may have greater relevance as standing CT screening becomes more available.