What causes osteoarthritis?

The cause of osteoarthritis, or degeneration of the cartilage in joints, is multi-factorial. There is a hereditary component. It's not genetic where, say, one fourth of all offspring will have this, but it does tend to run in families. If a person has a family history of early osteoarthritis, it's more likely that he or she will have early osteoarthritis than someone who does not, but it's not guaranteed. How much a person uses the joints is another contributing factor. Also, someone who is significantly overweight puts a lot more stress on the joints, wearing them out quicker, causing degeneration.

Debra Fulghum Bruce PhD
Healthcare Specialist

Exact causes are unknown, but common risk factors for osteoarthritis include:

  • increased age
  • injury
  • heavy, constant joint use
  • athletes
  • overweight
  • knee surgery
  • abnormal joint positions
  • changing forces or positions of joints
  • joint injury by other types of arthritis
  • lack of exercise
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Osteoarthritis is made worse by joint damage. You cannot distinguish arthritis caused by trauma versus atraumatic osteoarthritis. However, in either case, further trauma to the joint makes it worse.

The main risk factor for development of osteoarthritis is obesity; reducing body weight will reduce symptoms and slow progression. Watch as rheumatologist Natalie Azar, MD, discusses how genetics and obesity play main roles in osteoarthritis.

Dr. Grant Cooper, MD
Physical Medicine & Rehabilitation Specialist

Primary osteoarthritis tends to occur after age 45. A combination of genetic predisposition and normal "wear and tear" of the joints from repetitive microtrauma may contribute to its development.

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Dr. Kevin J. Soden, MD
Family Practitioner

Osteoarthritis is usually caused by repetitive trauma to the joint due to activities such as exercise or work.

The most common cause of osteoarthritis is wear and tear due to the activity of your life—especially if you're overweight, because every pound of weight adds about four pounds of pressure on your joints such as your knee. Other causes of osteoarthritis include heredity, alignment issues, developmental issues and even infections.

Dr. Christopher P. Chiodo, MD
Orthopedic Surgeon

Osteoarthritis may be caused by wear and tear or injury and generally develops over time. It involves the gradual erosion of a joint's surrounding cartilage, leaving less cushioning between bones, which in turn causes pain and sometimes inflammation. Since the feet support most of the body's weight, they are especially susceptible. Obesity can add to the problem by putting more pressure on joints. A recent government study, one of the largest ever to monitor the onset of osteoarthritis, found that obese people had the highest risk for developing osteoarthritis—which is why maintaining a healthy weight is so important. A severe foot injury or a history of previous injuries (as from playing sports) can also make the feet more susceptible to osteoarthritis.

Age is one of the greatest risk factors for osteoarthritis (OA). The general wear and tear of aging can erode the cartilage that supports and cushions the joints of the hands, spine, hips and knees so that bones rub against each other. This rubbing can cause the painful condition of osteoarthritis. More than a third of people age 65 and older have OA.

Also, being overweight or obese puts extra pressure on the knee and hip joints, which can lead to osteoarthritis. OA may also be hereditary. Other risk factors include:

  • joint defects
  • genetic defects
  • female gender
  • deformities and misaligned bones
  • injuries to the joint
  • occupations that require repetitive motions
  • other diseases, like gout or rheumatoid arthritis

According to the National Osteoporosis Foundation, osteoarthritis is the most common type of arthritis, affecting nearly 27 million Americans. It’s caused by a breakdown of cartilage in joints, resulting in reduced cushioning and, consequently, pain, stiffness and loss of movement in the affected joint. Major risk factors for the development of osteoarthritis include heredity, joint trauma, aging and obesity.

Most people think osteoarthritis happens because they’re getting older. That could be true, but there are reasons for osteoarthritis that you may not have thought about. Osteoarthritis happens when cartilage, the tissue that cushions the ends of your bones, wears away. So, instead of the bones gliding over each other when you move, they grind together. This causes stiffness, soreness and the inability to bend as you normally would.

Osteoarthritis has a number of causes. But there are three causes of osteoarthritis that might surprise you:

  • being overweight
  • lack of exercise
  • uneven wear and tear

Osteoarthritis is most often seen in the knees, hips, hands and spine.

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Dr. Michael T. Murray, ND
Naturopathic Medicine Specialist

Osteoarthritis (OA) is divided into two categories, primary and secondary. In primary OA, the degenerative "wear-and-tear" process occurs after a person turns 40. The cumulative effects of decades of use lead to the degenerative changes by stressing the collagen matrix of the cartilage. Damage to the cartilage results in the release of enzymes that further destroy cartilage components. With aging, the ability to restore and manufacture normal cartilage structures decreases. 

Secondary OA is associated with some predisposing factor that is responsible for the degenerative changes. Predisposing factors in secondary OA include inherited abnormalities in joint structure or function; trauma, including fractures along joint surfaces, surgery and other injuries to the joint; presence of abnormal cartilage; and previous inflammatory disease of joints, such as rheumatoid arthritis and gout.

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There are good reasons to believe that neither aging nor the normal use of joints causes osteoarthritis. But exactly what the cause of osteoarthritis is remains unknown. In one study, no obvious cause could be found in more than 90 percent of people with osteoarthritis.

There are hints that active disease processes are involved that upset the normal breakdown and remodeling of cartilage. Some researchers suggest that inappropriate loads placed on the bones may change the way their metabolism works. This can happen when the bones are used too much or not enough, when injuries occur that upset normal joint function, or when unusual stress is placed on the joint (by, say, operating a jackhammer).

Recent evidence suggests, too, that certain enzymes (metalloproteinases) are involved in the destruction of cartilage and bone in osteoarthritis. The loss of glycosaminoglycans (large molecules that help trap water) by cartilage during the disease process also may play a role.

Other conditions that can cause osteoarthritis include:

  • Injury to joints: Repeating movements that put stress on a joint can eventually lead to osteoarthritis. Apparently, movements that our joints are not used to will cause problems. Direct impact on joints also may loosen tendons or damage cartilage, which can lead to osteoarthritis.
  • Meniscus injury and repair of the knee: Many knee injuries also tear a meniscus. If the meniscus injury is severe enough, it may have to be repaired surgically. Both the injury and its repair increase the chances that osteoarthritis will develop in the affected knee.
  • Instability of weight-bearing joints: Small changes in the mechanics of a joint, such as instability or changed shape of the joint, may contribute to the development of osteoarthritis.
  • Inflammation of joints: Rheumatoid arthritis and several other, less common, types of arthritis with accompanying inflammation can lead to osteoarthritis.
Dr. Mehmet Oz, MD
Cardiologist (Heart Specialist)

Scientists used to think that osteoarthritis was a simple matter of wear and tear. Your knees, hips and other joints are formed by two bones. Tough tissue called cartilage protects the ends of those bones from rubbing against each other. But over time, cartilage can wear away. When bone starts scraping against bone, the result is pain and stiffness.

This theory hasn't changed, but scientists now think that other factors are involved in osteoarthritis, including:

  • Age: Just getting older increases you risk of OA.
  • Weight: Being overweight or obese sharply increases your risk of OA.
  • Gender: Women get OA more than men, especially after menopause.
  • Joint injuries: If you've ever hurt a joint, you're at greater risk of getting OA in that joint later on.
  • Gene defects: Some may cause people to lose cartilage prematurely.

You can't do anything about your age, sex or old joint injuries, but you can definitely reduce your risk of OA by losing weight.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.