Synovial fluid, made up mostly of a substance called hyaluronic acid, lines the joints, acting as a shock absorber and lubricant. As we age, cartilage begins to lose its flexibility and becomes more vulnerable to damage from overuse or injuries. Repeated injuries, such as those from playing very active sports or doing heavy labor, such as construction work, can also cause cartilage breakdown. As the cartilage cushion is worn away, the joint is put under increased stress. This causes further cartilage destruction.
Bones begin to thicken or change shape and joint spaces narrow, causing inflammation and pain.
In severe cases, all of the cushioning cartilage may be destroyed. Bone comes in direct contact with other bone, causing pain and limiting movement in the joint. Symptoms you may notice Pain is the major symptom of osteoarthritis and cartilage loss. Some people also experience swelling and inflammation. Others may feel no pain, even though X-rays show joint damage.