Ringbone is an osteoarthritic condition that most commonly affects the pastern joint (high ringbone), but also can affect the coffin joint (low ringbone). The term gets its name from the ring or enlargement that can, in the more severe cases, form a true ring or enlargement of bone surrounding the pastern joint just above the coronet band. It is a degenerative disorder that affects the pastern and/or coffin joints and has no cure.