Currently, about 20 million Americans are affected by osteoarthritis, and the prevalence of osteoarthritis is two-and-a-half times that of heart disease and six times that of cancer. It is projected that by 2030, 20% of Americans—about 70 million people—will have passed their sixty-fifth birthday and will be at risk for osteo-arthritis (National Institute of Arthritis, 2003). Similar percentages of most Western populations suffer from osteoarthritis (Statistisches Bundesamt Germany, 2003; Statistics Canada, 2003). The risk of developing osteo-arthritis is higher in African-Americans, Hispanics, and
Asians compared to Caucasians (Escalante and del Rincon, 2001; Jordan et al., 2003; Xu et al., 2003).
The incidence of clinically symptomatic osteoarthritis increases with increasing age, independent of site, and for both female and male populations (Felson et al., 1987; Oliveria et al., 1995; Verbrugge, 1995). Biological tissues undergo significant changes during the aging process including biological changes and associated changes in mechanical properties.
Although the incidence of osteoarthritis at the knee and hip is similar in male and female populations under the age of 60 years, the incidence in females over the age of 60 years increases at a faster rate than in males over the age of 60 years (Oliveria et al., 1995; Peyron et al., 1993). Differences or changes in hormone levels, in part, may account for these differences, although this association is still under debate (Richette et al., 2003). Estrogen, the female sex hormone, has been shown to affect biological tissue properties and turnover. For instance, in cartilage, increased estrogen levels have been related to increased matrix protein turnover (for review, see Richette et al. (2003)). In comparison, lower estrogen levels during adolescence may lead to increased femoral cartilage thickness and stiffness. In certain ligaments, higher estrogen levels are associated with greater stiffness (Romani et al., 2003), and the maximum voluntary force per cross-sectional area in skeletal muscle dramatically declines in post-menopausal women (Phillips et al., 1993). During menopause, estrogen levels decrease drastically. These reports suggest that lower estrogen levels during and after menopause may lead to lower matrix protein turnover in cartilage, greater cartilage stiffness, greater joint laxity, and lower muscle forces. These changes occur in addition to age-related physiological and morphological changes in biological tissues (see later) and may be, in part, responsible for higher incidence of idiopathic osteoarthritis in women after menopause.
Although osteoarthritis can affect most synovial joints of the upper and lower extremities and trunk (hand, wrist, ankle, knee, hip, neck, back), it is observed most frequently at the knee and rarely at the wrist and ankle (Neame et al., 2004; Oliveria et al., 1995). Potential reasons for the site specificity of osteoarthritis include structural and metabolic differences of biological tissues between joints, for instance the higher content of proteo-glycans and water in cartilage and decreased catabolic and increased anabolic activity of chondrocytes at the ankle compared to the knee (Kuettner and Cole, 2005). However, co-occurrence of hand and knee osteoarthritis in the same patient (Englund et al., 2004) suggests that not only local joint-specific biological and mechanical factors, but also global factors such as hereditary and environmental factors affecting the entire organism, may play a role in the development of osteoarthritis.
Cost to society Costs to the American society associated with osteo-arthritis currently exceed 80 billion dollars per year (National Institute of Arthritis, 2003). This number will increase with the increase in life expectancy and with the rapid aging of the population, especially as the baby-boomers will reach the age of 60 years within the next two decades and thus will be at greater risk of developing osteoarthritis. Currently, osteoarthritis is the sixth fastest growing disease in the United States (Forbers, 2005). Approximately two-thirds of the costs associated with osteoarthritis are indirect costs due to work loss and work disability payments (for review see Dunlop et al. (2003)).
Was this article helpful?
Did You Know That Herbs and Spices Have Been Used to Treat Rheumatoid Arthritis Successfully for Thousands of Years Do you suffer with rheumatoid arthritis Would you like to know which herbs and spices naturally reduce inflammation and pain 'Treating Rheumatoid Arthritis with Herbs, Spices and Roots' is a short report which shows you where to start.