Almost 21 million people in the United States are afflicted by osteoarthritis and it accounts for nearly 25% of all visits to primary care physicians. Moreover, close to 50% of those 65 and older will develop symptoms of this disorder This issue of Medical Clinics examines the clinically important aspects of osteoarthritis and features articles on the following topics: epidemiology; etiopathogenesis; the role of bone and meniscus in disease genesis; genetics; joint mechanics; symptoms, imaging; overview of management; obesity and management of body weight; the role of muscle in disease genesis; use of orthotic devices; the role of analgesics and intra-articular injections in disease management; potential pharmacologic treatments; and surgical interventions.