This horse developed some recurring abscesses in the right hind foot. They abscessed out, both at the bottom and directly above at the coronet. All together there were about four significant abscesses over the course of a year, that came out at the top. After that the horse stopped abscessing.
The hooves looked reasonable to begin with, but had excess concavity (sole contraction) in the hind feet. After the abscessing the sole contraction normalised and the hoof demonstrated normal concavity.
The photos show the difference at sole level 5 years apart. Note how the damage is reflected in the sole contour. The horse now has a much healthier foot. Despite the bone loss, sole production has recovered and a bit of extra laminar horn is filling the gap.
Despite the bone loss, the focus on developing a hoof with integrity, allowed the area to heal over. Only a small amount of widened white line remains in that area. Other than that, the white line appears tight and the horse has not been lame since the last abscess burst.
More than likely, the sole contraction contributed to the tissue and bone damage in that area. The abscessation was the body’s mechanism to remove any foreign body (bone fragments in this case). Once those were out, the area could heal over.