Can we use subchondral bone thickness on high-field magnetic resonance images to identify Thoroughbred racehorses at risk of catastrophic lateral condylar fracture?

This study investigates if there’s a link between the thickness of a horse’s subchondral bone, as seen on magnetic resonance imaging (MRI), and the risk of catastrophic lateral condylar fractures. The research found that greater subchondral bone depth in a specific part of the horse’s metacarpus was associated with increased fracture likelihood.

Research Methods and Participants

• The study was conducted as a case-control study, aimed at identifying the bone-level risk factors that make racehorses more susceptible to fractures.
• A total of 191 horse metacarpals (third metacarpus or MC3) were subjected to MRI. These specimens were sourced from both horses that had experienced a lateral condylar fracture of the MC3 and those that had not.
• The thickness of the dense subchondral or trabecular bone was measured at various sites around the distal end of the bone. The goal was to spot any differences in this thickness that could be associated with the likelihood of fractures.

Research Findings

• The results showed that denser subchondral or trabecular bone in the palmar half of the lateral parasagittal groove of the distal MC3 (a specific location in the horse’s lower leg) was linked to a higher chance of fracture.
• A Receiver Operator Characteristic analysis was used to find the best subchondral bone thickness cutoff that could predict the horse’s fracture status.
• The study estimated both positive and negative predictive values, using not only the study’s fracture prevalence but also a prevalence estimate for the larger racehorse population.

Conclusion and Future Recommendations

• The research highlighted a need for suitable pre-screening tests that can rule out true negative horses – those not at risk of fractures – and increase the prevalence of pre-fracture pathology in the horse population screened using MRI.
• Such a pre-screening test could potentially enhance the positive predictive value of the MRI scan, thus improving the diagnostic process of horses at risk for such fractures and potentially help prevent catastrophic racing injuries.