Osteoarthritis is the most common of all joint disorders. It is caused by the wearing away of the natural cartilage layer and may lead to the symptoms of joint wear. Osteoarthritis affects not only older people: whenever joints are highly stressed over many years, osteoarthritis may result, for example in athletes. Osteoarthritis may also develop as a late complication of accidents or already in earlier life due to a malformation or weakness of the joint.
The cartilage layer of joints serves as a kind of shock absorber. The smooth and elastic layer ensures an even, frictionless motion sequence and protects the joints during all movements.
In contrast with other types of human tissue (such as the skin, for example), cartilage has no potential of self-healing or repair. Injured or worn joint cartilage is therefore lost forever. This loss of the surface layer quickly leads to a painful limitation of function and movement.
The main symptom of osteoarthritis is pain. Initially, this typically manifests itself as “starting pain”, e.g. when beginning to walk after prolonged standing or when getting up after prolonged sitting. Later it appears as load-bearing pain. Often it leads to a habit of going easy on the joint. This causes further deterioration of the cartilage because cartilage depends on movement for the uptake of nutrients.
The most common form of osteoarthritis is so-called idiopathic osteoarthritis (joint wear of unknown causes), a typical symptom of old age. The disease takes a slow course and develops over many years. When pain and restriction of movement occur, the cartilage is incurably damaged.
A disorder with similar symptoms but other causes is chronic polyarthritis (joint rheumatism) which often affects several joints. A defence reaction of the body produces substances that swell the mucosa of the joint and lead to chronic joint inflammation with progressive destruction.