Pharmacologic treatment of osteoarthritis.

Current pharmacotherapy for osteoarthritis (OA) is aimed at relief of pain and functional disability. Although an inflammatory component may be found in some cases, there is little evidence that anti-inflammatory drugs commonly used in the treatment of OA provide more relief than simple analgesics. A growing body of knowledge about the pathophysiology of OA now offers opportunities to develop interventions aimed at retarding the progressive degeneration of articular cartilage. This is a function of an imbalance between cartilage matrix synthesis and breakdown. New and experimental treatments include oral, parenteral, and intra-articular agents, some of which are chemicals and others biological products. Their modes of action have generally not been established in humans, but may be inferred from in vitro culture systems and animal models. These mechanisms include inhibition of synovial cell-derived cytokines and chondrocyte-derived degradative enzymes, inactivation of superoxide free radicals, stimulation of matrix synthesis, and enhancement of synovial fluid lubrication. Many of these treatments have been shown to provide short- or long-term symptomatic improvement in clinical trials. Protection of cartilage or promotion of repair has been demonstrated in animal studies, but not convincingly in human OA studies.