Association of biomechanical properties of the calcified metacarpal articular surface with clinically assessable subchondral bone microstructure in thoroughbred racehorses
Non-invasive measures of bone quality and injury risk are an important area of investigation in Thoroughbred racehorses. Onset of race training in Thoroughbred racehorses is associated with adaptive improvement in biomechanical properties at the distal third metacarpal calcified articular surface. Repetitious high loading however can result in fatigue injuries of subchondral bone and calcified cartilage, particularly palmar/plantar osteochondral disease and third metacarpal/-tarsal condylar fractures. We aimed to determine the correlation between clinical computed tomography (clinical-CT) microstructural parameters, training history and calcified articular surface biomechanical properties and therefore potential fracture risk in the distal palmar third metacarpal condyle of Thoroughbred racehorses. Third metacarpal condyles were examined from 31 Thoroughbred horses, including horses in race training, resting or untrained. Samples were imaged with 100μm resolution clinical-CT (Somatom® Emotion®). Reference point indentation mechanical testing of the calcified articular surface was performed (BioDent™ Hfc). The association between indentation distance increase (IDI), an inverse measure of toughness and clinical-CT and training variables were assessed.