Gypsy, the Equine Encyclopedia, has something to say about ringbone. Like all Shetlands, she is always watching, learning and listening.
Ringbone is a raised bony ridge that forms around the pastern bone (just above the hoof). It is nearly always parallel to the coronary band (where the hoof attaches to the leg). Bone growth near the fetlock joint is more serious than if it forms closer to the coronary band.
This condition received the name “Ringbone” because it can sometimes form raised a ring all the way around the pastern bone. However, it most commonly it occurs on the front of the pastern.
Ringbone usually affects the front pasterns but not the hind. Ringbone can cause lameness or unsoundness. By the time a raised ridge is visible, it is usually quite chronic. However, sometimes this condition can be harmless and is merely unsightly.