An important point to be highlighted, initially, that are different exams and for different stages of osteoarthritis. But an important point is cost. X-rays are cheaper and certainly provide accurate diagnoses of osteoarthritis and their classification. MRIs are expensive, but are useful in the evaluation of mechanical joint problems, and are also great for an initial diagnosis of injuries due to bone failure. In routine practice, both are useful. But logically Rx ends up being the most used and in cases of advanced osteoarthritis they are the best choice of analysis.