About Osteoarthritis of the Knee
Osteoarthritis is the most common form of arthritis, affecting over 100 million people in the United States with over 48 million people suffering from osteoarthritis of the knee. It is a progressive disorder of the joints involving degradation of the intra-articular cartilage, joint lining, ligaments, and bone. The incidence of developing osteoarthritis of the knee over a lifetime is approximately 45%. Certain risk factors in conjunction with natural wear and tear lead to the breakdown of cartilage. Osteoarthritis is a chronic, progressive condition caused by inflammation of the soft tissue and bony structures of the joint, which worsens over time and leads to progressive thinning of articular cartilage. Other progressive effects include narrowing of the joint space, synovial membrane inflammation and thickening, osteophyte formation and increased density of subchondral bone. Inflammation of the synovium interrupts the natural chondrocyte metabolism, which is responsible for the production and maintenance of cartilage’s extracellular matrix. Osteoarthritic synovial fluid activates pro-inflammatory cytokines in active chondrocytes through autocrine and paracrine mechanisms. The cytokines, such as tumor necrosis factor (TNF-), interleukin-17 (IL-17), and interleukin-18 (IL-18), stimulate the synthesis of matrix metalloproteinase (MMPs) whose enzymatic activity leads to the degeneration of cartilage.
The global osteoarthritis therapeutics market continues to expand and is expected to exceed $3 billion by 2015. Despite the size and growth of the osteoarthritis of the knee market, few adequate treatment options currently exist for this chronic, debilitating disease.