What causes osteoarthritis?
Arthritis involves chronic inflammation of one or more joints in the body. Osteoarthritis (OA) is the most common type of arthritis. In people with OA, the cartilage in one or more joints deteriorates with time.
Cartilage is a tough, rubbery substance. Normally, it protects the ends of bones and allows joints to move easily. When the cartilage degenerates, the smooth surfaces of bones in joints become pitted and rough. This causes pain in the joint and can irritate the surrounding tissues. Over time, the cartilage may wear away completely. Bones in the joint that rub together can cause severe pain.
Some degradation of cartilage is part of the natural aging process. However, not everyone develops OA. The reasons one person develops the disease when someone similar does not is not well understood. Specific causes of OA may vary from person to person.
Risk factors for osteoarthritis
Certain factors are known to increase the risk of OA. Some of these factors are beyond your control. However, you can reduce the risk of developing OA from damage caused by lifestyle factors such as:
- overuse of joints
OA sometimes runs in families. If your parents or siblings have OA, you’re more likely to as well. Doctors don’t know why OA runs in families. No gene has yet been identified as the cause, but genes may contribute to OA risk.
OA is directly connected to wear and tear on joints. It becomes more common as people get older. According to the Centers for Disease Control and Prevention, more than one third of adults over the age of 65 have symptoms of OA.
OA can affect both men and women. According to the National Institutes of Health, it’s slightly more common in men until age 45. After that, it’s more common in women. This may reflect the different joint stressors experienced by men and women at different ages.
People who have injured a joint are more likely to develop OA in that joint.
Being overweight or obese puts increased stress and strain on the body. This increases the risk of OA in the joints. People who are overweight or obese are particularly susceptible to OA in the:
However, obesity is also associated with OA in non-weight-bearing joints, such as those in the hands. This suggests that extra mechanical stress on the joints or weight alone may not increase OA risk.
Repetitive actions can put undue stress on your joints, and occupations that require such repetitive actions can increase OA risk. Job tasks that fit this category might include:
- kneeling or squatting for more than an hour a day
- climbing stairs
People who regularly participate in joint-intensive sports may also have an increased OA risk.
Sitting or standing improperly can strain your joints. This can increase OA risk.
Other types of arthritis
Other types of arthritis can increase your risk of developing OA later in life. These include:
Other medical conditions
Medical conditions that affect joint health can affect your risk for OA. For example, bleeding disorders can cause bleeding in the joints. Conditions that affect blood flow or inflammation can also affect risk. Some medical conditions associated with OA include:
- Paget’s disease of bone
- underactive thyroid
Not everyone with OA has symptoms all the time. Most people with OA have symptoms that come and go throughout the day. Certain common triggers for OA symptoms have been identified. However, specific triggers may vary from person to person.
Lack of activity
Staying still for too long can cause your joints to stiffen. This makes movement more likely to hurt. Lack of activity during the night may partially explain why OA pain is often worse when people wake up.
Research has linked stress to exaggerated perceptions of pain.
Changes in weather can worsen symptoms of OA. People with OA are often especially sensitive to cold, damp weather.