The cannon bone should be short, wide and flat. Fetlocks are large and wide, free from swelling or windpuffs. The pasterns are of moderate length with an angle of 50-55 degrees. The hocks are severely angled from the point of the hock to the fetlock. The horse appears to stand under from the hock down.
Subjects horse to strain in hocks - causes curb, throughpin, and bog spavin.
Sickle hocked horses tend to interfere at the trot. They are often cow-hocked, making for a severe hind leg deficit. This prevents the horse from getting its legs under itself for collection. Hunters and jumpers will have trouble pushing off over jumps. Often associated with upright pasterns.