what causes osteoarthritis pain in a joint

Obesity. Maintaining an ideal weight or losing excess weight may help prevent osteoarthritis of the knees, hips, and back. Weight loss can also decrease the progression of OA.

Injury. People with joint injuries due to sports, work-related activity, or accidents may be at increased risk of developing OA. For example, athletes with knee-related injuries may be at higher risk of developing osteoarthritis of the knee. In addition, people who have had a severe back injury may be predisposed to develop osteoarthritis of the spine. People who have had a broken bone near a joint are prone to develop osteoarthritis in that joint.

Heredity. Some people have an inherited defect in one of the genes responsible for making cartilage. This can cause defective cartilage, which leads to more rapid deterioration of joints. People born with joint abnormalities are more likely to develop osteoarthritis, and those born with an abnormality of the spine (such as scoliosis, a curvature of the spine) are more likely to develop osteoarthritis of the spine.
Joint Overuse. Overuse of certain joints increases the risk of developing OA. For example, people in jobs requiring repeated bending of the knee are at increased risk for developing OA of the knee.
Age. Although age is a risk factor, research has shown that OA is not an inevitable part of aging