What happens when distal sesamoidean ligaments rupture?

What happens when distal sesamoidean ligaments rupture?

• A. Fetlock hyperextension and collapse of the stay mechanism, causing severe lameness
• B. Increased stay mechanism with improved weight bearing
• C. No change to stay mechanism
• D. Reduced lameness unrelated to stay mechanism

Answer: (A)

Distal sesamoidean ligaments act as tension cables that stabilize the fetlock and keep the stay apparatus functioning during weight bearing. They resist the tendency of the fetlock to over-extend when the limb is loaded and the muscles are relaxed. If these ligaments rupture, that passive restraint is lost, the fetlock can hyperextend, and the stay mechanism collapses. The horse then presents with severe lameness due to instability and inability to support weight through the limb.

Distal sesamoidean ligaments act as tension cables that stabilize the fetlock and keep the stay apparatus functioning during weight bearing. They resist the tendency of the fetlock to over-extend when the limb is loaded and the muscles are relaxed. If these ligaments rupture, that passive restraint is lost, the fetlock can hyperextend, and the stay mechanism collapses. The horse then presents with severe lameness due to instability and inability to support weight through the limb.