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Osteoarthritis (OA) is the most common type of arthritis affecting older people. OA affects different people differently. There are several risk factors associated with the development of OA. These include ethnicity, age, gender, genetic factors, bone density, nutritional factors, obesity, prior joint injuries and occupational factors. Obesity, hypertension, dyslipidemia, diabetes and insulin resistance tend to cluster into the so-called metabolic syndrome (MS). There are not many studies that have explored the relationship between MS and OA. The motivation for the study was to determine if there was an increased risk of cardiovascular diseases in subjects with OA.
Epidemiology of OA
Osteoarthritis (OA) is the most prevalent form of arthritis and a major cause of disability in people aged 65 and older (Lawrence, 1998). Osteoarthritis is a clinical syndrome of joint pain and dysfunction caused by joint degeneration. Current estimates are that 27 million people in the United States have OA (Helmick, 2008) and this number is expected to reach 60 million by the year 2020 (CDC, 1996). Approximately 10-30% of those affected with OA in the United States have significant pain and disability (Garstang, 2006). It has been estimated that by the year 2020, 12 million Americans are estimated to have limitation in some aspect of function because of OA (CDC, 1996). OA symptoms typically begin after age 40 and progress slowly (Arthritis Foundation, 2008). OA typically affects only certain joints, such as the hips, hands, knees, low back and neck. After age 50, women are more affected by OA than men (Lawrence, 1998). Loss of joint function as a result of OA overall is a major cause of work disability and reduced quality of life (Arthritis Foundation, 2008) The CDC estimates that OA and related arthritic conditions cost the U.S. economy nearly $128 billion per year in direct medical care and indirect expenses, includding lost wages and productivity (MMWR, 2007). The total annual cost of a person living with OA is approximately $5700 (Maetzel, 2004).
Pathogenesis of OA
The pathogenesis of OA is not fully understood, although multiple contributing factors are recognized including genetic, environmental, metabolic, and biomechanical factors (Kraus, 1997). Osteoarthritis can affect any synovial joint (Mandelbaum and Waddell, 2005). The normal joint is protected by biomechanical factors such as alignment and muscle strength, the lubrication provided by the synovial fluid, and the shock-absorbing function of bone and cartilage (Mandelbaum and Waddell, 2005). These functions get altered at both the macroscopic and cellular levels resulting in further joint destruction. It involves both destructive and reparative metabolic processes, with a variety of biochemical triggers in addition to mechanical injury of the joint (Mandelbaum and Waddell, 2005). The increased prevalence, chronic nature, lack of preventive services or cure of OA makes it a substantial economic burden for patients and healthcare systems (Brooks PM, 2006).