Osteoarthritis pathology begins in cartilage and involves progressively across the joint. Initially cracks develop on the surface of cartilage and it becomes irregular. Gradually these cracks get deeper and broader and erode a joint cartilage portion. This occurs in some places, while other areas of cartilage remain not involved.
Microscope chondrocytes multiply and congregate in clusters around areas of cartilage damage. These cells under the influence of some certain molecules that regulate the inflammatory process called enzymes release of cytokines and growth factors , this breach more matrix of cartilage. For this reason, the tight binding of the negatively charged molecules becomes loose and now cartilage is more capable of resisting the forces in compression and is more quickly downwards.
Under the effect of cytokines, cells called osteocytes bone just below the cartilage become active and cause bone become thickened and rigid.
Near areas of cartilage loss chondrocytes are also cartilage new form. This new cartilage is not organized and under the influence of cytokines gets vascularized. Blood vessels provide calcium which gets deposited in this cartilage and now it is converted to the os. This os is seen in the form of outgrowths called osteophytes. These can be seen in x-rays and are useful in diagnosis. Develop of osteophytes on the site of maximum loss of cartilage.
Under the influence of cytokines and growth factors, synovial tissue becomes inflamed. Number of cells in the increase in the synovium and synovial fluid quantity also increase. Enzymes are released in the synovial fluid trying to digest the chips of the loose cartilage. Sometimes the synovium can remain normal and lose these changes.
Swelling and deformation can produce stretching of ligaments, making joint unstable and vulnerable to injury. Pain causes the patient to avoid this leads to the weakening of muscle activity. These weak muscles are unable to support the articulation, effectively leading to more damage.
As can be seen that the inflammation and the breakdown of cartilage leads to weakening of protective joint that leads to failure like cartilage and generating a vicious circle that causes a rapid progression of the disease.
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This page was last updated June 10, 2009.
To learn more about osteoarthritis...
OA issue
Symptoms of osteoarthritis
Diagnosis OA
Treatment of osteoarthritis
Rewind pathology OA to OA
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