ABSTRACT
Arthritis af–icts as many as one in —ve Americans, or approximately 20% of the U.S. population [1]. There are more than 100 forms of arthritis, and the two most common and best-known types are osteoarthritis (OA) and rheumatoid arthritis (RA). OA is by far the most prevalent form affecting approximately 60% of all arthritis sufferers. RA is the second most common form of arthritis impinging on 1.3 million adults [1, 2]. OA is a condition in which low-grade in–ammation results in pain in the joints, caused by wearing of the cartilage that covers and acts as a cushion inside joints. OA is characterized by articular cartilage degradation with an accompanying periarticular bone response. OA of the knee and hip is a growing health concern because it is the second most common chronic disease leading to Social Security disability payments because of long-term absence from work [3]. It is prevalent in the aging population and affects roughly 12% of elderly (persons 60 years or older) [4]. Patients with OA have pain that typically worsens with weight bearing, including walking and standing. The debilitating pain induced by OA results in decreased movement leading to regional muscle atrophy. Indeed, OA sufferers account for 25% of visits to primary care physicians and half of all nonsteroidal anti-in–ammatory drug (NSAID) prescriptions. Consequently, OA imposes a tremendous socioeconomic burden on the U.S. public health system and diminishes the quality of life of millions of people.
