Osteoarthritis is a chronic progressive disease of the joints, resulting from the deterioration of the cartilage with subsequent change in the underlying (located just under the articular cartilage) bone tissue, development of edge osteophytes, joint deformities, as well as development of moderately expressed synovitis. Osteoarthrosis, osteoarthritis, deforming arthrosis are presented in the 10th International Classification of Diseases as synonyms.