The cause of arthrosis is unknown, so it is thought that the disease is multifactorial, that is caused by several simultaneous causes. It can be stated in general that the state of joint equilibrium is maintained by a normal load exerted on a normal cartilage, therefore all the factors capable of modifying this state can be considered risk factors. The imbalance can derive from the abnormal influence of the factors acting on the load (mechanical stress, obesity, malformations, traumas and microtraumas) or on cartilage (inflammation, genetic predisposition, metabolic disorders, aging) or on both. The extent and severity of the process may also depend on the number of factors involved, their size and their duration of action.
The main risk factors that predispose to the development of osteoarthritis are:
Age : the modifications of senile cartilage involve a loss of elasticity and resistance to stress and favor the damaging action of other factors.
Mechanical factors : very important for joint balance. Malformations or joint malpositions are especially important in osteoarthritis of the knee, which is quite common in the female population, probably due to excessive use, repeated microtraumas and dislocations. Professional and sports activities have been seen to be responsible for the onset of the disease. Among workers there is arthritis of the shoulders, elbows and hands in pneumatic hammer workers, hip osteoarthritis in professional dancers, knee osteoarthritis in miners and lumbar osteoarthritis in truck or bus drivers. For athletes, judgment is more difficult, as there can be many causes. In football players, for example, one of these may be the frequent breaking of the meniscuses. An underlying weakness of the ligaments may instead explain the osteoarthritis of tennis players' shoulders. The ascertainment of an increased frequency of hand arthrosis in judoists is also suggestive. As for traumas, violent trauma with fracture can generate an atrose indirectly, due to instability or incongruity of the articular heads. However, it seems that a responsibility can also be ascribed to the contusion on the cartilage, without fracture.
Inheritance : some inherited diseases such as hemochromatosis, Ehlers-Danlos syndrome and Marfan syndrome, compromise metabolism and / or joint function and may generate some types of secondary arthrosis. It has long been known that osteoarthritis of the fingers often recognizes a family transmission.
Obesity and diseases of the endocrine system : obesity is without a doubt the most important risk factor for the development of knee osteoarthritis in both sexes. Instead, some doubt remains about its role in determining that of the hip, of which, however, it influences the type of evolution, aggravating it. Also some alterations of the endocrine system, such as diabetes mellitus and gout, regardless of obesity, have been called into question as possible risk factors.
Inflammation : its role is highly valued, both for its ability to cause arthrosis, and for its influence on its progression. In the first case the forms of arthrosis that derive from arthritis are inserted, especially rheumatoid arthritis and, in the second case, the intervention of a real inflammatory process is considered in the joints affected by arthrosis.
