Magnetic Resonance Imaging Measurements of the Proximal Palmar Cortex of the Third Metacarpal Bone and the Suspensory Ligament in Non-Lame Endurance Horses before and after Six Months of Training.
Authors: Likon Ines, Dyson Sue, Nagy Annamaria
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary Proximal metacarpal pathology represents a significant concern in endurance horses, yet the adaptive responses of structures in this region to systematic training remain poorly characterised. Likon and colleagues used low-field MRI to track objective structural changes in the palmar cortex of the third metacarpal bone and suspensory ligament in six novice and six experienced horses, obtaining detailed measurements at multiple levels before and after six months of competitive endurance training. Notably, experienced horses demonstrated significantly greater medial cortical thickness at 2 and 3 cm distal to the carpometacarpal joint compared to novice horses—a finding likely reflecting years of accumulated training stimulus—and all horses showed a consistent pattern of medial-to-lateral thickness asymmetry. Importantly, six months of training produced no statistically detectable changes in cortical thickness or suspensory ligament dimensions using low-field MRI, suggesting either that adaptive remodelling requires longer timeframes to become radiographically evident or that changes at this stage occur at a subcellular level beyond current imaging resolution. For practitioners, these findings underscore that structural strengthening of the proximal metacarpus represents a chronic adaptation process; short-term conditioning periods may improve functional capacity without generating measurable morphological changes, and endurance horses may benefit from strategically extended training programmes that allow sufficient time for protective skeletal adaptation before competing at intensity.
Read the full abstract on PubMed
Practical Takeaways
- •Baseline structural changes in the proximal metacarpus appear to reflect years of cumulative training rather than acute training responses over short timeframes.
- •Low-field MRI may not be sensitive enough to detect early exercise-induced remodeling in these structures within a six-month training period, limiting its utility for monitoring acute adaptations.
- •The natural medial-lateral asymmetry of cortical thickness should be considered when evaluating pathology or asymmetrical lameness in endurance horses.
Key Findings
- •Experienced horses showed significantly thicker medial proximal palmar cortex of the third metacarpal bone at 2-3 cm distal to the carpometacarpal joint compared to novice horses, likely reflecting cumulative long-term exercise effects.
- •The medial aspect of the proximal palmar cortex was significantly thicker than the lateral aspect across all horses studied.
- •Six months of endurance training produced no detectable changes in proximal palmar cortex thickness or suspensory ligament dimensions on low-field MR imaging.
- •Mediolateral asymmetry exists in the proximal metacarpal region, with medial predominance of cortical thickness.