Biomechanical investigation of the association between suspensory ligament injury and lateral condylar fracture in thoroughbred racehorses.
Authors: Le Jeune Sarah S, Macdonald Melinda H, Stover Susan M, Taylor Ken T, Gerdes Max
Journal: Veterinary surgery : VS
Summary
# Editorial Summary Loss of medial branch suspensory ligament (MBSL) integrity may predispose Thoroughbreds to lateral condylar fractures by fundamentally altering load distribution across the metacarpophalangeal joint. Le Jeune and colleagues conducted a controlled in vitro study on seven cadaveric Thoroughbred forelimbs, measuring bone surface strains and joint angles during axial compression before and after partial MBSL transection at physiologically relevant loads (1,400–5,600 N). Following MBSL injury, all lateral condylar strains increased significantly whilst medial condylar strains decreased, indicating a pathological shift in load-bearing that concentrates compressive and tensile forces on the lateral condyle—the site of common catastrophic fractures in racing Thoroughbreds. Whilst joint angles did not change significantly post-transection, the biomechanical data suggest that even partial MBSL damage compromises the ligament's stabilising function, creating a mechanical environment favouring lateral condylar failure. This finding has direct clinical relevance: early detection and management of suspensory ligament injuries, particularly medial branch involvement identified through ultrasound or advanced imaging, may help prevent progression to condylar fracture in racing animals.
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Practical Takeaways
- •Suspensory ligament damage, particularly involving the medial branch, should be considered a risk factor for lateral condylar fracture in racehorses; early detection and management of ligament lesions may help prevent fracture
- •Horses with MBSL injuries require modified training and load management to reduce peak forces through the metacarpophalangeal region until ligament healing is complete
- •Diagnostic imaging for condylar stress or microfractures should be considered in racehorses presenting with concurrent suspensory ligament injury to identify fracture risk before catastrophic failure occurs
Key Findings
- •Partial transection of the medial branch of the suspensory ligament (MBSL) significantly increased lateral condylar bone surface strains across all measured locations
- •Lateral condylar bone strains increased proportionally with axial load (1,400–5,600 N), with higher strains observed after MBSL transection at all load levels
- •Medial condylar abaxial surface strains were significantly lower after MBSL transection, indicating load redistribution away from the medial condyle
- •Loss of MBSL integrity may increase risk of lateral condylar fracture in Thoroughbreds by amplifying mechanical stress on the lateral condyle