Preface–Osteoarthritis: From the Simple X-ray to Compositional MRI: What Have We Learned?

Abstract

Osteoarthritis (OA) is an extraordinarily prevalent disease. Approximately 50 million Americans and 800 million people worldwide have reported having OA and approximately 20 million Americans arthritis-associated activity limitations. OA of the knee, which is the joint most well investigated, affects an estimated 6% of adults and is a leading cause of disability among adults in the United States. The economic burden of arthritis is estimated to be approximately $120 billion, which is equivalent to 1.2% of the gross domestic product. OA, however, remains an enigmatic disease. At the meeting of the Osteoarthritis Research Society International held in Montreal, Canada, September 10–13, 2009, it was reported that 10% of the population has asymptomatic OA, 58% of persons with knee OA have no radiographic findings, and 80% of persons who have had an anterior cruciate ligament develop OA. Today, knowledge of the pathophysiology and natural history of OA is so limited that most of the patients and even physicians believe that there is little we can do to treat or prevent the disease other than trying to alleviate the inflammatory symptoms when they occur. In the meantime, several epidemiologic studies were or are currently under way to help understand the relationship between structure and function and how best to intervene in this disease process. Imaging is playing a major role in these studies and providing insights in understanding of this complex disease. In this issue of Rheumatic Disease Clinics of North America, world-renowned researchers and clinicians report on the latest advances in understanding of the disease using imaging. Dr Hunter presents insights on epidemiology of the disease and how to tackle its risk factors. Drs Hunter and Wilson describe the importance of alignment and mechanics in pathophysiology of OA and in the treatment of the disease.