Osteoarthritis is a cartilage wear and an alteration of the tissues constituting the joint, which occurs because of a long or intense use of the joint, but also because of a more or less physiological degeneration of these tissues. But we do not exactly know the specific causes of osteoarthritis, even if we know some of the contributing factors ...
The bones of the joints are all covered with cartilage. This allows them to slide easily against each other during movement. When the cartilage wears out and starts to be destroyed, the bones of the joint rub against each other and are damaged. At the level of the pressure zones, the cartilage becomes fragile, splits, is damaged. In the long term, it can be destroyed, the bones of the osteoarthritic joints are then in direct contact: these in turn are altered.
They repair themselves but imperfectly: irregular bone condensation replaces the normal bone, and osteophytosis appears. These are bone growths, such as "parrot beaks" named by doctors, and sometimes seen on radios vertebrae.
Fragments of cartilage and bone may be present in the synovial fluid. A synovitis, that is to say an inflammatory reaction, can then occur and the joint become swollen, red, hot, painful. It is called inflammatory thrust of the joint.
Genetic factors may carry weight in the development of the disease. If the disease can start to show signs of pain from 40 or 50 years, in most cases, it can appear discreetly much earlier.
Mechanical factors may be responsible for osteoarthritis:
- Poor axing of the lower limb: a genu valgum (knee inside) or a genu varum (knee outside) can give osteoarthritis because the joint is poorly focused, the weight of the body carries more on one side of a knee than on the other and the cartilages of the tibia wear out faster on the supporting side.
- High level sport can also be the cause of osteoarthritis on particularly stressed joints.
- The trauma of a particular joint, joint fracture, repetitive sprains, dislocation, may be responsible for the onset of osteoarthritis.