Osteoarthritis is defined for research purposes at different levels, like clinical and radiological basis. This definition makes the basis for diagnosis of the disease. Clinical basis involves a certain set of symptoms like pain, morning stiffness, warm and tender joints etc.
Radiological set of criteria involves certain changes in the joint spaces and the bones that are appreciated on the x-ray of the relevant joints. The confusing character of the disease is that the radiological signs of bone and joint lesions may not always align with the clinical signs and symptoms.
Epidemiology
In contrast with the earlier belief where osteoarthritis were widely known to be a result of trauma or aging, it is now recognized as multifactorial in origin and epidemiology. The number of patients goes up in the middle aged population. It is also seen to be coupled more strongly with the female gender, however, given the large distribution; males are not seen as an exception. Nearly 80% of the population above 75 years is affected by osteoarthritis. Other factors like trauma, sports involvement, environmental factors, and the role of genetic components are discussed in further detail later in the article.