Ossa sesamoidea
The equine foot and fetlock contain both proximal sesamoid bones (at the back of the fetlock joint) and the distal sesamoid bone, commonly called the navicular bone. The proximal sesamoid bones act as pulleys for the flexor tendons at the fetlock and provide attachment for the suspensory apparatus. The navicular bone serves this role within the podotrochlear apparatus in the foot. Both sets of sesamoid bones are subject to high mechanical stress and are prone to inflammation, degeneration, and fracture.
Proximal sesamoid fractures and sesamoiditis are important causes of fetlock lameness. Navicular syndrome involves the distal sesamoid and surrounding structures. Diagnosis uses clinical examination, nerve blocks, and imaging. Prognosis depends on the specific injury.
Acute fetlock swelling or lameness after fast work, or chronic heel pain, should be evaluated. Protective boots can help reduce risk in some disciplines.
Proximal sesamoid fractures and sesamoiditis are important causes of fetlock lameness. Navicular syndrome involves the distal sesamoid and surrounding structures. Diagnosis uses clinical examination, nerve blocks, and imaging. Prognosis depends on the specific injury.
Acute fetlock swelling or lameness after fast work, or chronic heel pain, should be evaluated. Protective boots can help reduce risk in some disciplines.
See the Sesamoid Bones on our interactive 3D horse model. Open 3D Model