The intercarpal ligaments of the equine midcarpal joint, Part 2: The role of the palmar intercarpal ligaments in the restraint of dorsal displacement of the proximal row of carpal bones.

This study examines the role of palmar intercarpal ligaments in the midcarpal joint, specifically their contribution to preventing the backward movement of carpal bones in horses. While they are relatively small, the findings suggest they play a significant role in maintaining skeletal structure and suggest that a deeper understanding of these ligaments is vital for preventing and treating injuries.

Research Methodology

• The researchers conducted a biomechanical study on eight forelimbs of six thoroughbred horses that had died of unrelated causes.
• They simulated movement in the joint by displacing the horse’s radius backward while the midcarpal joint was in full extension.
• The displacement force at a joint displacement of 1.5mm was calculated from the load-displacement curve.
• They then repeated this procedure after sectioning a ligament or pair of ligaments, using the change in restraining force to determine the ligament’s role in preventing displacement.
• They also measured the cross-sectional areas of the ligaments at the level of the midcarpal joint.

Findings

• The study found that the collateral ligaments play a major role in restraining dorsal displacement, or movement toward the rear, in horses (P < .001).
• Of the joints tested, the smaller palmar intercarpal ligaments contributed more to restraining force than the palmar carpal ligament (P < .05).
• The average contribution to preventing dorsal displacement calculated was 62.8 +/- 3.4 for the collateral ligaments, 14.5 +/- 1.4 for the PCL, and 22.7 +/- 2.2 for the palmar intercarpal ligaments.
• The cross-sectional area of the ligaments as a percentage of the total ligamentous area was 9.0 +/- 0.3 for the palmar intercarpal ligaments, 27.1 +/- 3.0 for the PCL, and 63.8 +/- 2.8 for the collateral ligaments.

Conclusion

• Despite their small size, palmar intercarpal ligaments have a crucial role in preventing the dorsal displacement of the proximal row of carpal bones in horses.
• Understanding the biophysical role and contribution of these ligaments is necessary for interpreting the cause and extent of potential ligamentous injuries, as well as for the development and administration of effective prevention and treatment strategies.