The Structure of a Joint
Cartilage, the smooth, rubbery connective tissue on the end of bones, cushions joints and helps them move smoothly and easily. A lifetime of walking, exercising, and moving takes a toll on your cartilage. The degeneration of cartilage can cause chronic inflammation in the joint. This inflammation can further break down the cartilage over time. The cartilage may wear away completely if it is left untreated.
A membrane called the synovium produces a thick fluid that helps keep the cartilage healthy and makes joints run smoothly. The synovium can become inflamed and thickened as OA progresses. The inflammation produces extra fluid within the joint, resulting in swelling.
As cartilage deteriorates, adjacent bones may no longer have sufficient lubrication from the synovial fluid and cushioning from the cartilage. Once the bone surfaces come in direct contact, this results in additional pain and inflammation to the surrounding tissues. As bones continually scrape one another, they can become thicker and begin growing osteophytes, or bone spurs. The joints most commonly affected by OA are in the hands, feet, spine, and weight-bearing joints, such as the hips and knees.
The Aging Body
The older we get, the more common it is to experience mild soreness or aching when you stand, climb stairs, or exercise. The body does not recover as quickly as it did in younger years.
Another cause for the soreness: Cartilage naturally deteriorates. The smooth tissue that cushions joints and helps them move more easily disappears with age. In a sense, the body’s natural shock absorbers are wearing out, which means you begin feeling more of the physical toll your body is experiencing. In addition, we lose muscle tone and bone strength the older we get. That can make physically demanding tasks more difficult and taxing on the body.
A common factor for developing osteoarthritis is age: Most people with osteoarthritis are over the age of 55. Still, other factors increase a person’s chances for developing the disease. These factors include:
Excess weight. Being obese or overweight puts additional stress on joints, cartilage, and bones, especially those in the knees. It also means you’re less likely to be physically active.
Family history. Genetics may make a person more likely to develop OA. If you have family members with the disease, you may be at an increased risk of developing OA, too.
Gender. Before age 45, men are more likely to develop osteoarthritis. After 50, women are more likely to develop OA than men. The difference becomes almost even around age 80.
Occupation. Certain occupations, such as those in construction, agriculture, cleaning, and retail, increase a person’s risk for developing OA. Their bodies are used more rigorously as part of their job, which means their joints are worked more and likely age faster than people who have a desk job.
Younger, more active people can also develop osteoarthritis. However, it’s often the result of a trauma, such as a sport injury or accident. A history of physical injuries or accidents can increase a person’s chance of later developing osteoarthritis.