What Is Osteoarthritis? Symptoms, Causes, Diagnosis, Treatment, and Prevention

Osteoarthritis (OA) is the most common type of arthritis, or inflammation of the joints (where the ends of two adjacent bones meet).

It is also called degenerative joint disease or “wear and tear” arthritis because it most often develops slowly over time, as people age. (1,2)

People with osteoarthritis typically have joint pain or stiffness that’s most often caused by damage to cartilage, the slippery tissue that covers the ends of bones in the joints.

Other common symptoms of osteoarthritis include:

• Swelling around the joint
• Clicking or cracking sound when the joint bends
• Reduced range of motion
• Muscle weakness around the joint (1,2,3)

Osteoarthritis can occur in any joint, but it most commonly affects the joints of the hands, hips, and knees, as well as the lower back and neck. (3,4)

Learn More About the Signs and Symptoms of Osteoarthritis

Within normal, healthy joints is cartilage — a firm, rubbery material mostly made up of a matrix (a gel-like substance with a high water content) and two types of proteins (collagen and proteoglycan).

Cartilage serves as a shock absorber that allows bones to glide over each other when a joint bends or straightens. Thanks to its water content, cartilage can change shape to absorb impacts when it is compressed.

In people with osteoarthritis, the cartilage loses a lot of its water content (often through normal wear and tear) and deteriorates, reducing its ability to absorb shocks.

Without this cartilage, the bones underneath can rub together, causing pain and inflammation at the joint. Cartilage can undergo some repair when damaged — slowly, since it contains no blood vessels — but the body does not produce new cartilage after injury. (2)

Primary Osteoarthritis vs. Secondary Osteoarthritis

Osteoarthritis is classified as either primary or secondary.

Cartilage breaks down in both types of osteoarthritis; the difference between the two types lies in the underlying cause of this breakdown.

Primary osteoarthritis, which is more common, is the “wear and tear” type of osteoarthritis that develops over time without a specific cause. It affects women more often than men, especially after menopausal age. Most often, primary osteoarthritis affects the fingers, spine, hips, knees, and big toes. (2,5,6)

Secondary osteoarthritis, on the other hand, has a specific cause other than normal wear and tear. For example, young people can get secondary osteoarthritis if they’re athletes who use their joints a lot or if they have jobs that require the same bodily movements over and over.

Causes of secondary osteoarthritis include:

• Injury — sports-related injuries in particular
• Obesity, which adds extra weight onto joints, causing them to wear faster
• Physical inactivity
• Congenital (present from birth) joint disorders, such as congenital hip dysplasia
• Scoliosis (curvature of spine)
• Hemophilia and other disorders that cause bleeding in the joints
• Disorders that block the blood supply near a joint, such as avascular necrosis
• Other types of inflammatory arthritis, such as rheumatoid arthritis and gout
• Being “double-jointed” or having another condition associated with increased joint laxity
• Abnormal growths of bone and cartilage
• Paget’s disease, a chronic disease marked by deterioration of bone tissue (2,3,5,7,8,9)

Osteoarthritis Risk Factors

Several factors can lead to the development of osteoarthritis. Risk factors may vary depending on the joint involved.

Older age and being female are common risk factors for primary osteoarthritis. Primary osteoarthritis occurs in equal frequency for men and women younger than age 55, but it is more common in women among adults older than age 55. (8)

Having a close relative with osteoarthritis or a family history of the disease is also a risk factor for primary osteoarthritis. In fact, most people with primary osteoarthritis have family members with the condition. (2)

Risk factors for secondary osteoarthritis include:

• Being overweight or obese, which particularly affects and puts more wear and tear on the joints of the hips, knees, ankles, and feet
• Previous joint injury
• Fractures and injuries to the cartilage and ligaments in the joints
• An occupation that requires repetitive use of certain joints, such as a lot of kneeling, lifting, or walking up flights of stairs
• Playing sports, especially those that involve direct impact on joints or involve joint twisting or throwing motions
• Lack of physical activity
• Type 2 diabetes and elevated glucose levels (2,10)

There is no single symptom or test that can diagnose osteoarthritis. Diagnosis is based on a review of your symptoms and medical history, a physical examination, and laboratory and imaging tests.

In reviewing your medical history and giving you a physical examination, your doctor will look for signs that indicate osteoarthritis, including:

• Pain that worsens with activity and gets better with rest
• Age over 45 years
• Morning stiffness that lasts less than 30 minutes
• Enlargement of the joints
• Reduced range of motion (11,12)

The physical exam may also reveal various other signs of osteoarthritis, including joint tenderness, joint swelling, crepitation (joint crackling during movement), altered gait, and instability of the joint. (8)

Your healthcare provider may conduct various other tests if he suspects you might have osteoarthritis.

Blood tests and other laboratory tests will not help diagnose osteoarthritis but may help rule out other potential causes of your symptoms, such as inflammatory arthritis.

Imaging tests, including X-rays, magnetic resonance imaging (MRI) scans, and ultrasounds, are usually not necessary. But they can help rule out other causes of symptoms and show the extent of damage to your cartilage, bones, and ligaments. (8,11,12)

Prognosis of Osteoarthritis

Pain from osteoarthritis can make it difficult to enjoy — or even perform — everyday activities, such as running errands, cleaning house, exercising, or getting good rest. Some research suggests that osteoarthritis symptoms and restlessness from a lack of activity can interfere with sleep. In fact, about 70 percent of people with osteoarthritis have sleep issues. (8,13)

The course of osteoarthritis varies between people and depends on the joints affected. Pain and disability due to hip osteoarthritis usually worsens over time, while osteoarthritis affecting the fingers initially causes intermittent pain and stiffness but fewer symptoms later on. (12)

The disease may rapidly progress if you have:

• Obesity
• Advanced age
• Osteoarthritis affecting multiple joints
• Bowlegs (varus deformity) (11)

Osteoarthritis is a long-lasting condition with no cure.

Osteoarthritis is a chronic condition that typically gets worse over time if left untreated.

Treatments aim to reduce pain and other symptoms, improve joint function, slow the progression of the disease, and maintain quality of life. (1)

Common treatments for osteoarthritis include:

• Injections of thick liquids (hyaluronic acid gel) into the joints to mimic the functionality of normal cartilage
• Supportive or assistive devices, such as crutches, shoe inserts, splints, and braces
• Physical activity, including aerobics and strength training exercises
• Physical therapy and occupational therapy
• Hot and cold therapies
• Weight loss (if necessary)
• Self-management strategies
• Surgery (2,4,9,11,14)

The American College of Rheumatology and Arthritis Foundation produces guidelines and recommendations for the treatment of hip, knee, and hand osteoarthritis. In their latest guidelines, published in February 2020, the experts strongly recommended the following treatments: (15)

• Exercise
• Weight loss (for knee and hip osteoarthritis in people who are overweight)
• Self-sufficiency and self-management programs
• Tai chi
• Certain supportive or assistive devices, such as canes and knee braces
• Oral nonsteroidal anti-inflammatory drugs (NSAIDs)
• Topical NSAIDs and intra-articular glucocorticoid injections for knee osteoarthritis

Medications for Osteoarthritis

Various medications may play a role in osteoarthritis treatment, including: (1,15)

• NSAIDs
• Analgesics (pain relievers), including acetaminophen (Tylenol) and opioids
• Corticosteroids
• The antidepressant duloxetine (Cymbalta) and the antiseizure drug pregabalin (Lyrica), which are FDA-approved to treat osteoarthritis pain
• Lidocaine, capsaicin cream, and other topical counter-irritants

Recent research suggests various other medications may soon be available to treat osteoarthritis. These include:

• An anti-inflammatory antibody called canakinumab (16)
• Injections of adenosine triphosphate to help regrow lost cartilage (17)
• Injections of a novel molecule blocker to halt cartilage destruction (18)
• Growth factors delivered via nanoparticles to regenerate cartilage (19)

Alternative and Complementary Therapies for Osteoarthritis

Various alternative and complementary therapies may be used in conjunction with standard treatments to reduce osteoarthritis. These include:

• Acupuncture
• Glucosamine and chondroitin sulfate
• Tai chi or yoga
• Nutritional supplements, including fish oil and curcumin (active ingredient in turmeric)
• Transcutaneous electrical nerve stimulation (TENS)
• Platelet-rich plasma injections
• Massage therapy
• Adenosyl-L-methionine (SAMe) (2,20,21)

Speak with your doctor before trying any alternative and complementary treatments for osteoarthritis, as many of them lack clear evidence of benefit and may carry risks. For example, the American College of Rheumatology and the Arthritis Foundation do not recommend TENS, glucosamine, or chondroitin, but conditionally recommend (on a case-by-case basis) yoga. (15)

RELATED: Natural Remedies for Osteoarthritis Pain

Prevention of Osteoarthritis

Since most cases of osteoarthritis are caused by normal wear and tear on the joints, it’s not possible to prevent it. But you may be able to reduce your risk of getting osteoarthritis with these measures:

• Maintain an active lifestyle, nutritious diet, and healthy weight
• Exercise regularly to strengthen muscles that protect joints, especially weight-bearing joints (knee, hip, or ankle)
• Avoid using a painful joint
• Practice good posture
• Avoid injury to joints (8,9,22)

Osteoarthritis can be debilitating. If it’s not treated, your movement may become limited over time.

Complications of osteoarthritis can vary depending on the severity of the condition and the joint involved.

Potential complications and related disabilities include:

• Long-term (chronic) pain
• Difficulty moving and performing daily tasks
• Inability to work
• Infection in the joint
• Stress fractures
• Pinched nerve (in spinal osteoarthritis)
• Joint deformities — hard or bony nodules that form where two bones come together, often giving the joint a knobby or knotted appearance
• Misaligned joints
• Decreased joint motion
• Nerve root damage
• Impaired balance and increased risk of falling (4,11,23,24)

Osteoarthritis is the most common joint disorder in the United States, but the prevalence of osteoarthritis varies slightly from one scientific study to another.

In the United States, nearly 27 million adults have clinical osteoarthritis, according to a study from 2008. (25) A more recent study, from 2015, found that an estimated 30.8 million U.S. adults (13.4 percent of the adult population) had osteoarthritis between 2008 and 2011. (26)

Estimates from the U.S. Centers for Disease Control and Prevention (CDC) place the prevalence of osteoarthritis at more than 32.5 million adults. (4) Worldwide, it affects an estimated 302 million people and is a leading cause of disability among older adults. (15)

Knee Osteoarthritis, or KOA, Is Not Rare

The knee is the joint most commonly affected by osteoarthritis. Approximately 14 million people have symptomatic knee osteoarthritis, according to a 2016 study. More than half these people are younger than 65. (27)

Research suggests that people who are overweight or obese are 2.5 or 4.6 times, respectively, more likely to have knee osteoarthritis than those who are “normal” weight. (28)

Other studies have shown that knee osteoarthritis has doubled in prevalence since the mid-20th century, but this increase cannot be explained by increased longevity and body mass index alone. (29)

Hand osteoarthritis is also fairly common.

While the lifetime risk of developing symptomatic knee osteoarthritis is 45 percent, one study found that the lifetime risk of systematic hand osteoarthritis is about 40 percent. Nearly 1 in 2 women and 1 in 4 men have an estimated lifetime risk of developing hand osteoarthritis by age 85.

Comparatively, the lifetime risk of developing hip osteoarthritis is 25 percent. (30)

Osteoarthritis vs. Rheumatoid Arthritis: What Is the Difference?

Several different types of arthritis exist. Aside from osteoarthritis, other common types include rheumatoid arthritis (RA), gout, and lupus. (11)

Osteoarthritis and RA affect the body differently.

In osteoarthritis, which is most often a mechanical (wear and tear) disease, the cartilage that covers the ends of the bones in a joint is damaged by multiple different causes.

But in RA, the joint lining becomes inflamed and eventually erodes the joint.

This disease is considered an autoimmune condition because the immune system mistakes joint linings for foreign objects and attacks them, resulting in inflammation.

Additionally, unlike osteoarthritis, RA develops because of a combination of genetic and environmental factors, such as tobacco exposure. (11,31)

Learn More About Rheumatoid Arthritis vs. Osteoarthritis Joint Pain

The available evidence on the correlation between race and ethnicity and osteoarthritis is conflicting, and more research is needed on outcomes for Black, Indigenous, and People of Color (BIPOC) communities in the United States.

Some Asian populations have a lower risk of osteoarthritis, according to the CDC. And while some studies suggest that Black American women are more likely to develop knee osteoarthritis than Black men and white people generally, other studies have found no such connection. (4,10)

Osteoarthritis can be primary or secondary.

Cartilage breaks down in both types; the difference between primary and secondary lies in the underlying cause. Primary osteoarthritis is from wear and tear that develops over time, without one specific cause. It is more common, and it affects women more often than men, especially after menopause. (2,6,11)

Secondary osteoarthritis has a specific cause other than normal wear and tear. For example, young people can get secondary osteoarthritis if they’re athletes who use their joints a lot or if they have jobs that require the same bodily movements over and over. Specific causes of secondary osteoarthritis, which are listed in the Primary vs. Secondary Osteoarthritis section, include obesity, injury, and having other types of arthritis. (2,3,7,8,9,11)

Favorite Orgs for Essential Osteoarthritis Info

Arthritis Foundation

The Arthritis Foundation is a nonprofit organization dedicated to helping people with arthritis live their best lives through science, advocacy, and community connections. It also publishes the magazine Arthritis Today. Its website has numerous guides and articles for osteoarthritis and other types of arthritis, including about how to reduce your risk of falls and medical treatments for osteoarthritis.

American College of Rheumatology

While the American College of Rheumatology’s mission is to help rheumatologists succeed (it even publishes the journals Arthritis & Rheumatology and Arthritis Care & Research), the organization has a web portal dedicated to patients and their caregivers. There you will find guides about disorders of the joints, muscles, and ligaments, including osteoarthritis, to teach you about the symptoms, diagnosis, and treatment of the disorders, among other things. It also contains patient education videos on topics such as when you should see a rheumatologist.

CreakyJoints

A support, education, advocacy, and research organization for people living with rheumatic disorders, CreakyJoints is dedicated to raising awareness of all forms of arthritis, including osteoarthritis. Their activities include educating people about treatment and management strategies for these disorders.

The National Institute of Arthritis and Musculoskeletal and Skin Diseases

NIAMSD is the United States’ premier institute for research support, scientific training, and dissemination of information about arthritis, including osteoarthritis. It includes both basic and in-depth guides on osteoarthritis and various other arthritis, musculoskeletal, and skin diseases. This includes information on who treats the diseases and the progress of research on them.

Mayo Clinic

The Mayo Clinic website is a great initial resource when you’re first diagnosed with osteoarthritis and want to help your loved ones understand what you’re going through. The site offers basic information about osteoarthritis that can help you get a handle on the disorder’s symptoms, diagnosis, and treatment options.

U.S. Centers for Disease Control and Prevention

The CDC strives to protect the American public from public health, safety, and security threats through the control and prevention of diseases. Its guide on osteoarthritis includes basic information on its symptoms, risk factors, and treatment, as well as steps you and your loved ones can take to manage your osteoarthritis.

Favorite Annual Meetings

American College of Rheumatology Annual Meeting

This annual meeting hosts 16,000 rheumatologists, rheumatology health professionals, fellows in training, patient advocates, and exhibitors from more than 100 countries. The convention includes more than 450 sessions that provide opportunities for attendees to improve their professional development, network, and access the latest rheumatology research and clinical applications.

Favorite Online Support Network for Arthritis

Live Yes! Arthritis Network

This network, hosted by the Arthritis Foundation, provides various lines of support to help people with arthritis live life to the fullest. This includes online forums and a virtual connection group to empower people with arthritis to gain confidence in dealing with their disease proactively.