What mechanisms are involved in …

Osteoporosis is a disease that affects the bones and not the joints as in osteoarthritis. It consists in an accelerated loss of bone mass and impaired bone architecture. As a result, bones become fragile, brittle and more easily susceptible to fractures.

The following pictures (image of a bone biopsy, analysed by a microtomograph) show the effects of osteoporosis on the bone matrix.

Fig. 1 : Normal bone tissue.

Fig. 2 : Schematic diagram showing significant osteoporosis. In osteoporosis, there are perforations in the trabeculae and disruption of trabecular bone microarchitecture which constitute bone fragility

Osteoarthritis, in contrast to osteoporosis, is a disease of the joint, i.e. the contact areas between the bones (hips, knees, knuckles, etc.).

• The cartilage covering the ends of bones inside the joint wears out, fissures, splits and breaks up. Bony projections called bone spurs or osteophytes may form around the edge of the joint.
• Consequently, movements became more painful, more difficult and limited.

To learn more about the formation mechanisms of osteoarthritic lesions, take a look at the section "Understanding."