10 Surprising Facts About Osteoarthritis

Where it strikes, gender differences, mortality, and more

Knee pain
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Osteoarthritis (OA) is often called "wear and tear" arthritis. It used to be considered just a consequence of aging.

Bow now, researchers know it's a more complex disease process than that. OA develops when the cartilage inside a joint breaks down. (Cartilage helps bones glide over each other.)

This article will look at some important information about osteoarthritis, including what kinds there are, where it most often strikes, who gets OA, and even how it can lead to death.

Most Common Form of Arthritis

An estimated 32.5 million American adults have OA.

Arthritis comes in more than 100 different forms. But osteoarthritis is by far the most common. OA affects:

  • 13.9% of people over age 24
  • 33.6% of people over age 64


Unlike many forms of arthritis, OA is not an autoimmune disease. It's considered a degenerative disease.

ARTHRITIS TYPE U.S. PREVALENCE
Osteoarthritis 32.5 million
Gout  8.3 million
Psoriatic Arthritis 2.25 million
Rheumatoid Arthritis 1.5 million
Ankylosing Spondylitis 1 million
Juvenile Arthritis 300,000
Source: Arthritis National Research Foundation

Types of Osteoarthritis

The two main types of osteoarthritis are defined by what causes the condition.

  • Primary OA has no known underlying cause or genetic predisposition. It's sometimes called idiopathic OA.
  • Secondary OA is caused by another medical condition or trauma to the joint such as a sports injury or repetitive use.

Medical conditions that can lead to secondary OA include:

Most Commonly Affected Joints

OA can affect any joint. It's more common in the ones that are used more and are prone to injuries or repetitive stress trauma.

The joints that are most commonly involved in OA are:

Knee OA is the most common. It's estimated to affect at least 19% of Americans over 45.

Every year in the U.S., doctors perform a million OA-related joint-replacement surgeries on knees and hips alone.

Recap

About 32.5 million Americans have osteoarthritis. It's the most common form and can be primary or secondary to conditions like RA and gout.

The most commonly affected joints are the knees, hips, hands, feet and ankles, and back and neck.

Sex Differences

The sex you were assigned at birth makes a difference in your OA risk.

  • In people under 45, OA is more common in males
  • In people 45 and older, OA is more common in females
  • 62% of people with OA are female

Females are more than 40% more likely than males to have knee OA. After age 60 the prevalence rates are:

  • 10% of males
  • 13% of females

Research suggests that the differences may be due to:

  • Fluctuations of female hormones
  • A tendency for females to carry more weight
  • Different ways of moving lead to greater joint strain
  • Differences in the musculoskeletal symptom (e.g., less knee cartilage than males)

Osteoarthritis and Mortality Risk

You usually don't think of arthritis as a killer disease. But osteoarthritis is associated with an increased risk of death from:

  • Cardiovascular disease
  • Diabetes
  • Kidney disease

An estimated 500 deaths per year are directly attributed to OA-related factors. And that number may be too low. OA's true contribution to mortality is hard to judge.

For example, deaths from complications due to NSAID use aren't counted, even though they can be the cause of OA-related kidney disease.

It may be that pain from OA leads to less exercise and movement, which contributes to weight gain. Higher weight is linked to heart disease and diabetes.

Even so, there's no evidence that OA, on its own, shortens your life span. One 2019 study even reported a longer life span in people with OA.

Major Cause of Disability

Many people find themselves sidelined when they develop knee osteoarthritis. It's among the leading causes of disability in people over 60.

  • About 80% of people with OA have a limited range of motion.
  • About 25% cannot perform activities of daily living.
  • 30% say it's hard to stoop, bend, or kneel
  • 20% have trouble walking 3 blocks or handling large objects

Statistics from 2015 show that people with knee osteoarthritis missed about 10 days of work that year, compared to the average person's 7.5 missed days.

Working-age people with OA are unemployed more often than people without OA. This is likely because of OA-related limitations.

Reducing Your Risk

Risk factors for developing osteoarthritis include:

  • Age: OA is most common after age 40.
  • Hormones: Menopause changes appear tied to OA.
  • Previous injury: Trauma to a joint increases its risk.
  • Other conditions: RA, gout, and several other disorders contribute to cartilage wear.
  • Genetics: OA runs in families and is believed to involve a genetic component.

If you're high risk and want to lower your odds of developing OA, or if you want to slow it down, you have several options:

Recap

Females are more likely to have OA. About 500 deaths per year are attributed to the condition. OA increases the risk of dying from heart disease, kidney disease, or diabetes.

People with OA are more likely to miss work and be unemployed. A healthy lifestyle can lower your OA risk.

Genetics and OA

OA is believed to have a genetic component. Researchers say about 20-35% of knee OA and between 40% and 80% of hip and hand OA may be determined by genetics.

So far, 90 locations on the human genome have been linked to the development of OA. More important, though, are changes in gene expression (epigenetics) that happen throughout your life.

Ancestry and ethnicity play a role as well:

  • Black Americans are the most likely to have symptomatic knee OA
  • Hip OA is lower in people with Asian heritage

Imaging Findings

Not everyone with evidence of OA on imaging tests has symptoms.

For example, about 80% of people over age 55 have X-ray evidence of osteoarthritis. But only about 60% of them have symptoms.

The degree of damage visible on an X-ray isn't always relevant, either. X-rays don't detect early cartilage damage. Sometimes a person with severe pain has minimal findings.

X-rays do show:

  • Narrowed space between joints, where cartilage has worn away
  • Bone spurs, which are common in degenerating joint
  • Increased bone density (subchondral sclerosis), which is often found around narrowed joint spaces

Affects Overall Health

Osteoarthritis is often not the only health problem someone has. Approximately 40% of adults diagnosed with knee OA report that their health is either poor or fair.

Fall-related injuries can have a major impact on health. In one study, more than 50% of people with knee OA said they'd fallen in the previous year.

Researchers found a worse health-related quality of life in people with knee OA and a history of falling than in other groups.

The CDC says one in five falls leads to a serious injury. Falls can cause broken bones and head injuries. They're especially dangerous for someone taking blood thinners.

Recap

Genetics are a significant cause of OA risk. Symptomatic knee OA is most common in Black people.

X-ray findings often don't match reported pain and other symptoms. OA increases your risk of falling, which can lead to broken bones and head injuries.

Summary

OA is the most common form of arthritis. It can be primary or secondary. The knees, hips, and hands are most often affected. Those assigned female are more likely to have OA.

About 500 OA-related deaths are reported each year. People with OA are at increased risk of death from diabetes and heart or kidney disease.

OA is a major cause of disability. It's linked to absenteeism and unemployment. You can lower your OA risk by managing weight, protecting joints, and living a healthy lifestyle.

Genetics make up a large portion of your OA risk. Black people are most likely to have symptomatic knee OA. Asians have a lower rate of hip OA.

X-rays may show very little damage in someone with severe pain or severe damage in someone with no symptoms. OA impacts your overall health. Fall risk is high and falling can result in serious injuries.

A Word From Verywell

Osteoarthritis is a serious condition that can have very real impacts on your life and health. The good news is that researchers have learned a lot about it and that's led to better treatments.

More than ever, you have treatment options that can help you stay mobile and active, minimize pain, and keep you enjoying life.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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