ABSTRACT
There is evidence that certain knee conditions, such as osteoarthritis of the knee, have a strong genetic component and occur in some individuals, regardless of exposure. Table 1 presents data on the prevalence of episodes of knee pain lasting 1 month and of osteoarthritis of the knee in the general population in the USA (from the National Health and Nutrition Examination Survey in the USA, “NHANES II, 1971-75,” sampling about 110 000 individuals annually). Osteoarthritis of the knee is a problem of latemiddle age onwards, in the general population, whereas knee pain is very common, even in young people, and may appear before any radiological changes indicative of osteoarthritis. Similarly, those with osteoarthritis of the knee do not necessarily report knee pain.
