Definition: What is Osteoarthritis? Also known as degenerative chronic arthropathy, osteoarthritis is the most common joint disease today. It is most often linked to aging. Therefore, it only appears at a certain age. According to the French Society of Rheumatology, osteoarthritis affects only 3% of French people under the age of 45 years old. On the other hand, it affects 65% of people over the age of 65, and 80% of people over the age of 80. This disease results in the degeneration of the cartilage that lines the bony ends of the joints. Its thickness is reduced, causing dysfunctions in the joints where the bones do not slide well against each other. As of today, the real cause of this destructive disease remains unknown, though several factors have been mentioned.Causes of Osteoarthritis Age is one major cause of osteoarthritis, but the disease can also be linked to metabolic dysfunction, excessive pressure, and natural fragility of the cartilage. As such, sources of mechanical stress on the joints, such as being overweight, frequently carrying heavy loads, or too much physical activity can increase the risk of damaging the cartilage. Sequelae such as joint fractures, sprains, or dislocations can also be contributing factors, as can other diseases of the joints. Nevertheless, researchers have highlighted a hereditary character in some cases. Therefore, genetics - or more specifically, mutations of certain genes - can play a role in the development of osteoarthritis. That said, this does not concern all forms of the disease. In fact, this degeneration can affect different joints from the shoulder to the knee, through the hip, wrist, and ankle.