Strain of the musculus interosseus medius and its rami extensorii in the horse, deduced from in vivo kinematics.

This research examined the strain experienced by specific ligaments in a horse’s forelimb during different types of movement. The study used regression models and data from both in vivo kinematics and in vitro limb loading experiments to reach the conclusions.

Methodology

• The study focused on the strains of the musculus interosseus medius (also known as the suspensory ligament) and its rami extensorii (extensor branches) in a horse’s forelimb.
• The researchers used changes in the angles of the metacarpophalangeal and distal interphalangeal joints to deduce the strains.
• In vitro limb loading experiments were conducted, with regression models fitted to strains and joint angle combinations to create a basis for comparison.
• The team then studied the kinematics (the physics of motion) of eight live horses as they walked, trotted, and cantered to establish the in vivo strains.

Findings

• The extensor branches showed a strain of about 1.0% at the moment of hoof impact. This indicates these branches work to passively extend the interphalangeal joints just before impact, and prevent flexion (bending) of the pastern joint immediately afterwards.
• The maximal strain experienced by the suspensory ligament was 3.4% while walking, 5.6% while trotting, and 6.3% during a slow canter. This shows the strain increases correspondingly with the speed and impact of the horse’s movements.

Implications

• The findings provide a concrete understanding of the strains experienced by these particular ligaments during different types of movement. This could be used to inform injury prevention strategies or recovery plans for equine athletes.
• The methodologies adopted in this study – especially the use of regression models and the in vitro limb loading experiments – could provide valuable reference for future research into animal locomotion and biomechanics.