Primary osteoarthritis (OA) causes joint pain, swelling, and tenderness. It can affect a person’s mobility and quality of life, but treatment can often help. Primary OA has no known cause, whereas secondary OA results from an injury or another condition.

According to the Arthritis Foundation (AF), there are over 100 different types of arthritis and related diseases.

Primary OA is the most common, affecting most people by age 65 and about 80% of people over age 75. The condition causes pain, stiffness, and tenderness in and around affected joints.

This article reviews primary OA, its symptoms, causes, treatment, and more.

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Doctors classify OA into two types: primary and secondary.

Primary OA has no known cause, though liifestyle factors may increase a person’s risk of primary OA. The cause of secondary OA is often an injury or a preexisting condition, such as osteoporosis.

Primary OA is the most common form of arthritis in older adults. It is a disease of the whole joint that may result from weakened bones and connective tissues and inflammation, according to the Arthritis Foundation.

Joints affected by OA have damage to the cartilage that protects the end of bones. Cartilage allows bones to glide smoothly across each other. When it wears away, bones rub against each other, causing pain and inflammation.

OA may be asymptomatic for some people, while others have a significantly decreased quality of life. It can affect one or multiple joints and is common in the knees, hips, and hands. That said, it can affect any joint in the body.

Pain associated with movement is the most common symptom of primary OA.

Another term for primary OA is wear-and-tear arthritis. This is because it may result from overuse and aging. However, this does not mean that everyone will get primary OA in older age. People can make lifestyle choices that reduce their risk of developing OA.

Learn more about OA.

The primary symptom of OA is joint pain that gets worse with use and improves with rest. Many people find that their pain peaks in the afternoon or early evening as well as when they wake up in the morning. Stiffness in the joint is also common.

Experiencing pain can discourage people from being active, making stiffness and pain even worse over the long term.

Doctors divide primary OA pain into two types:

  • sharp, sudden pain in and around the joint that happens when a person moves
  • dull, aching pain, which may intensify as the condition progresses

People with OA often experience flares, which are periods of worsening symptoms. Local injuries to the joint may cause flares through overexertion but sometimes they happen without an obvious trigger.

Other symptoms of primary OA include:

  • stiffness
  • tenderness
  • crepitus, which is a snapping or popping sound in the joint, particularly in the knees
  • instability
  • limited range of movement
  • joint swelling
  • structural changes

Learn more about OA flare.

Symptoms in different joints

Primary OA can affect joints in different ways. For example:

  • OA in the knees: With OA in the knees, a person’s knees may develop crepitus when moving. This is caused by air bubbles in the fluid surrounding the joint or by the snapping of tightly stretched ligaments.
  • OA in the hips: Pain in the hips may radiate to the buttocks or groin if a person has OA in the hips.
  • OA in the feet: Pain may be primarily in the big toe with OA in the feet.
  • OA in the fingers: With OA in the fingers, a person’s fingers may swell or develop bony growths, which affect their shape.

Arthritis resources

To discover more evidence-based information and resources for arthritis, visit our dedicated hub.

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Experts do not exactly know what causes OA. It may be due to a combination of environmental and genetic factors, with an estimated 30–65% of cases likely resulting from epigenetics, according to a 2022 overview of the condition.

Epigenetics refers to how environmental factors and people’s behavior may cause changes to the way genes work. This combination of factors can lead to the development of arthritis.

According to the 2022 overview, three processes are involved in causing OA. They include:

Overuse of the joint and aging are the most common factors in OA.

The biggest risk factor of primary OA is older age, according to the 2022 overview of the condition. Experts think that age-related loss of muscle, failure of the joints to resist damage over time, and increased bone turnover account for this increased risk.

Females have a higher risk of developing the condition than males, per the 2022 overview. This may be due to:

  • bone density
  • joint alignment
  • ligament strength
  • pregnancy and menopause

A person’s anatomy may also increase their risk of OA. When joints are not aligned property or a person has structural changes in the joints from birth, it can increase the risk of joint damage, making OA more likely.

Other potential risk factors can include:

Learn how to increase bone density naturally.

People who experience joint pain and stiffness may wish to consult a doctor for a diagnosis.

During the appointment, a doctor will likely:

  • review the person’s medical history
  • ask about their symptoms
  • ask about family medical history
  • perform a physical examination
  • inspect the affected joints

Though no test can detect OA, doctors may order blood tests to rule out other causes of joint pain. They may check for inflammatory markers to rule out rheumatoid arthritis (RA) or other underlying causes.

Doctors may also order imaging tests to better examine the joints. The most common is an X-ray, though they may also order an MRI scan or ultrasound.

Find out what arthritis looks like on an MRI scan.

Treatment for OA focuses on relieving symptoms and preventing flares since there is no cure.

Treatments can include:

People can also reduce the chance of flares and manage them when they happen by:

Learn about 11 effective home remedies for arthritis.

The following sections provide answers to frequently asked questions about osteoarthritis.

Is primary OA a disability?

The Social Security Administration does not specifically list OA as a disability. However, a person may qualify for benefits under section 1.00: musculoskeletal disorders.

To qualify, a person will need to show evidence of significant, long lasting physical limitation. A person should work with a doctor to determine their eligibility and start the application process if they feel they qualify.

What are the stages of osteoarthritis?

There are three stages of OA based on pain levels:

  • Early OA: Pain is sharp and predictable. It may limit high impact activities.
  • Mid OA: Pain is increasingly constant and may affect daily activities. There may be unpredictable pain and joint locking.
  • Advanced OA: People experience a dull ache most of the time combined with unpredictable sharp pain. This pain restricts movement and daily activities.

A person may wish to see a doctor if they notice joint pain, stiffness, or tenderness. Though anyone can develop primary OA, people over age 65 have a higher risk.

A doctor can help diagnose and treat the condition. They may recommend testing to check for the presence of other forms of arthritis or underlying conditions that may be causing the joint pain.

A person with OA should consider consulting a doctor if their symptoms worsen. This could be a sign of disease progression, and a doctor may recommend adjusting their treatment.

OA does not have a cure. Making healthy lifestyle choices and learning how to manage symptoms can help people cope with their condition. As OA worsens, doctors may recommend different treatments, including surgery.

Primary OA is the most common form of arthritis. It primarily affects people over age 65, but it can affect anyone at any age. The most common symptoms are pain, stiffness, and tenderness in the affected joints.

The cause may be a combination of environmental and genetic factors. How a person uses their joints and their lifestyle choices can affect their risk of developing OA.

A person can treat the symptoms of primary OA in various ways, including pain medication, assistive devices, and lifestyle changes. Staying active and maintaining a healthy weight can strengthen the muscles around the joints and reduce pressure on them.

With careful management, many people with OA can live active, healthy lives.