Bone remodelling deregulation

If a bone is repeatedly subjected to excessive mechanical stresses (the navicular bone in a show-jumper, for example) this will lead to excessive remodellingChange in the shape of the bone as compared with its normal shape: the contours of the bone are changed in an X-ray. of the bony area in question.

This leads to the development of areas affected by what is known as "lysis" (which are washed out, less calcified, less dense) or areas of "sclerosisIncreased bone density: the area is whiter in an X-ray." (which are more calcified, denser, less flexible).

These changes can be seen on X-rays.

On the other hand, when the bone is subject to fewer stresses and strains (when a horse is convalescing or resting), bone tissue demineralises and becomes less dense.

Finally, as the bone resorption phase (the work of the osteoclasts) is far quicker than the bone formation phase (the work of the osteoblasts), decalcified areas of lysis may appear on areas subject to excessive stress: there is not enough time for bone densification to occur, and this leads to excessive resorption.