Who Gets Osteoarthritis?

Abstract Osteoarthritis, has existed as far back as the prehistoric eras-it has been found in dinosaur skeletons, and affects all mammals. Studies of skeleton X-rays from all ages show that if one lives long enough, osteoarthritis will develop in some joints. However, even though more than 80% of X-rays in people older than 75 years have osteoarthritis of the knee, less than 30% of people will ever develop knee pain from their osteoarthritis. Other estimates are that 10-15% of all Americans suffer from osteoarthritis knee pain. Clearly there is a large discrepancy between those that have X-ray evidence of osteoarthritis and those who eventually develop joint pain; however, the reasons for this are not yet clear. The older we get, the higher the chance of getting osteoarthritis, with a nearly 90% chance of X-ray findings in some joint by age 75. However, after the seventh decade the incidence appears to plateau, and this may mean that those who reach this age without symptoms are not likely to get them or that it has not yet been carefully studied in older individuals. While osteoarthritis appears to be an inescapable cause of aging, there is still no clear link between the normal aging process and the articular cartilage loss seen with osteoarthritis. Here we will review the risk factors for developing osteoarthritis (summarized in Table 3, at the end of the section).