Osteoarthritis is considered to be a disease with many possible causes. The onset of osteoarthritis, its severity and degree of pathological processes progression are determined by the following factors:
Chronic microtraumas of cartilagilages
The main cause of osteoarthritis can be a mismatch between the mechanical load on the chondral surface and the ability of cartilage tissue to resist this load. Therefore, osteoarthritis tends to develop in individuals engaged in hard physical work involving mechanical overloading on joints due to frequent stereotyped movements and especially in athletes. Adverse effects can also be caused by work in a monotonous posture involving bent knee joints or a sitting position with pressure on the knees. The stress on knee joints increases if combined with obesity.
Congenital malformations of joints
Dysplasias contribute to chronic microinjuries of cartilage and lead to the decrease in the articular surfaces congruence, which results in displacements of load axes in joints. The risk of developing osteoarthritis in individuals with congenital defects of locomotor system is increased by 7.7 times.
The most important risk factor of developing a symptomatic (i.e., clinically detectable) and radiographically proven osteoarthritis. It has been proved that the incidence of osteoarthritis for men and women with body mass index 30-35 is 4 times higher than for people with a normal BMI. It has been established that each 5 kg of excess body weight present a 40% risk of developing diseases of joints and, on the contrary, a 5 kg reduction in body weight leads to a reduction in clinical symptoms.
Development of osteoarthritis of the interphalangeal joints of hands with concomitant erosive changes in articular cartilages is 10 times more common in women, due to the autosomal dominant inheritance of this disorder in females and a recessive transmission of this trait in males. Newly discovered defects in gene responsible for Type 2 collagen production lead to the development of this condition.
Acute or chronic infectious arthritis, including tuberculous arthritis, non-specific inflammation of the joint, rheumatoid arthritis, etc lead to the development of osteoarthritis. Identification of specific immunoglobulins and complement components deposition in the articular surfaces suggests their involvement in the progression of osteoarthritis.
Disorders of proprioceptive impulses lead to decreased tone in the muscle near the hip and, consequently, to increased mechanical stress on the joint. E.g. a normally developed quadriceps can compensate for not less than 30% load on the knee joint; however, in the case of pathologic impulsation the muscle does not receive information from the brain about the strain required to perform its function, and the joint begins experiencing a physical overload.
In particular, so-called "deposition" diseases, such as hemochromatosis, ochronosis, chondrocalcinosis, gout. The deposition of various substances in the cartilage matrix tends to lead to direct damage of chondrocytes and secondary disorders of shock absorbing ability of the cartilage.