Osteoarthritis

Osteoarthritis

There are over 100 different types of arthritis conditions affecting over 20 million people in the United States, of those Osteoarthritis is the most common. It affects as many pople as all other types of arthritis combined. Arthritis is the leading cause of disability among older adults. Joint diseases account for half of all chronic conditions in persons aged 65 years and over. The prevalence of Osteoarthirtis is high and will get even higher as the number of older Americans increases. Because of its prevalence it is recognized as a significant public health problem.

Osteoarthritis is a type of arthritis that is caused by inflammation, breakdown, and eventual loss of the cartilage of the joints. Cartilage is a protein substance that serves as a "cushion" between the bones of the joints. Osteoarthritis is also known as degenerative arthritis. Most cases of osteoarthritis have no known cause, and are called primary osteoarthritis. When the cause of the osteoarthritis is known, the condition is called secondary osteoarthritis (3). Primary osteoarthritis is mostly related to aging. After prolonged use of joints, the cartilage begins to degenerate by flaking or forming tiny crevasses. In advanced cases, there is a total loss of the cartilage cushion between the bones of the joints. Loss of cartilage cushion causes friction between the bones, leading to pain and minimized movement of the joint(s). Inflammation of the cartilage can also stimulate new bone outgrowths (spurs) to form around the joints. These spurs may cause the joint to enlarge and press on other nearby structures such as nerves or tendons. This can lead to significant pain, further limitations in joint motion, tendonitis and other problems. Secondary osteoarthritis is caused by another disease or condition. Conditions that can lead to secondary osteoarthritis include obesity, repeated trauma or surgery to the joint structures, abnormal joints at birth (congenital abnormalities), gout, diabetes, and other hormone disorders (3).

The biologic factors leading to the deterioration of cartilage in osteoarthritis are not entirely understood. Many experts now believe that osteoarthritis results from a genetic susceptibility that causes some biologic response to injuries to the joint, which in turn leads to progressive deterioration of cartilage.

Researchers report a higher correlation of osteoarthritis between parents and children or between siblings than between husbands and wives. Genetic factors are thought to be involved in about half of osteoarthritis cases in the hands and hips and a somewhat lower percentage of cases in the knee. Multi-generational studies in Iceland indicate that some families are genetically predisposed to develop Osteoarthritis of the hip. On the other hand, people of Asian, African and Indian descent are less likely to develop hip Osteoarthritis. A single gene defect leads to an uncommon sub-type of Osteoarthritis, called primary generalize osteoarthritis.

A number of genes are under investigation that might contribute to an inherited risk. For example, mutations in the ank gene may be important in some cases. The ank gene regulates pyrophosphate, a chemical that inhibits the formation of mineral deposits, and may