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Osteoarthritis and Inflammation: Exploring a Possible Link

Linda Crampton is an experienced teacher with a first-class honors degree in biology. She writes about the scientific basis of disease.

Osteoarthritis in the fingers; a bony enlargement known as a Heberden's node is located next to a fingernail

Osteoarthritis in the fingers; a bony enlargement known as a Heberden's node is located next to a fingernail

The Nature of Osteoarthritis

Osteoarthritis is a disorder in which the cartilage in a joint degenerates and eventually disappears. The cartilage normally covers the ends of the bones in a joint and acts as a low-friction cushion between them as the bones move. When the cartilage is absent, the end of one bone rubs against the end of another, causing pain and difficulty in movement. Osteoarthritis is often a symptom of aging, but it may appear at any age due to an injury to a joint.

It was once thought that osteoarthritis was caused solely by wear and tear and involved no inflammation, unlike rheumatoid arthritis. The latter is an autoimmune and inflammatory condition that affects joints and other parts of the body as well. Researchers now say that inflammation is at least sometimes involved in osteoarthritis. It may not be as severe as that found in rheumatoid arthritis, but it may still be significant.

Who Gets the Disease?

Osteoarthritis is the most common form of arthritis. It's also known as degenerative arthritis or degenerative joint disease. Its name is sometimes abbreviated as OA. OA can affect any joint in the body, but it most commonly appears in joints located in the spine, hips, knees, feet, or hands.

Though the disorder is most common in older people, it can develop in anyone if a joint is malformed or injured. Research indicates that the majority of people in North America will have some degree of osteoarthritis by the time they are seventy. Not everyone will experience every symptom of the disorder. For many people, however, osteoarthritis is a painful disease. It can also be disabling.

The synovial joint is the most common type of joint in our body and is the site of osteoarthritis development.

What Happens to a Joint in OA?

A joint is a region where two bones meet. The type of cartilage that covers the ends of the bones is known as hyaline cartilage. It's a stiff but flexible material that is very slippery and allows bones to move over each other smoothly with low friction. If this cartilage gradually disappears, as it does in osteoarthritis, the ends of the bones will rub together.

The cartilage in a joint is sometimes known as articular cartilage. The body may form extra bone in a joint that lacks this cartilage. The extra bone may form irregular projections called bone spurs or osteophytes. Pieces of bone spurs may break off and be trapped in the joint, along with broken bits of cartilage. It's thought that the pieces of cartilage and/or the bits of bone sometimes irritate the membrane that lines the joint capsule, or the synovium, causing inflammation. There are additional theories to explain why the joint lining may become inflamed, however.

Possible Symptoms of OA

There may be no symptoms of osteoarthritis. Some people experience problems, however, which may be severe.

  • A person with OA may experience pain when moving the affected joint or when putting weight on it.
  • The joint may be stiff, especially after a person wakes up or after they have been inactive for a while.
  • There may be limitation in movement. The presence of osteophytes may further limit movement.
  • Bone spurs in a joint may produce a knobby appearance.
  • There may be a creaking, crackling or grating sound or sensation when the joint is moved. This sound is known as crepitation or crepitus.

Although there are treatments to make osteoarthritis more bearable, there is no cure for the disease, other than replacing the diseased joint with an artificial joint. Therefore, researchers (and patients) are very interested in finding ways to stop the progression of OA.

I've had osteoarthritis in my neck for years. I sometimes experience discomfort from the problem, but in general it doesn't bother me much. I hope the condition doesn't worsen as I get older.

Do You Have Arthritis?

Types of Inflammation

Acute Inflammation

Acute inflammation appears rapidly and lasts for a short period of time. It's a normal body response to an infection or an injury and is usually a beneficial process. It's characterized by an increased blood flow to the injured area. The blood carries white blood cells and proteins to fight bacteria and remove damaged tissue cells. The blood vessels become more permeable during inflammation, allowing the helpful substances to leave the blood and enter the injured tissue. Possible signs and symptoms of acute inflammation are heat, swelling, redness, and pain.

Chronic Inflammation

Chronic inflammation lasts for a long time. It may be weaker than the acute form. Sometimes the acute condition becomes chronic instead of being resolved, however. In this situation, the concentrations of white blood cells and of proteins associated with the inflammation remain abnormally high and can damage tissues. This can lead to health problems. Both types of inflammation may be involved in osteoarthritis.

The synovium is also called the synovial membrane or the synovial lining.

The synovium is also called the synovial membrane or the synovial lining.

Ligaments are fibrous structures that join one bone to another at a joint. Tendons are fibrous structures that join muscles to bones at a joint. The entheses are transition areas where ligaments and tendons join to a bone. A bursa is a fluid-filled sac that acts as a cushion that reduces friction during movement of body parts.

A Possible Cause of Joint Inflammation

Based on what I've read, inflammation is being found in osteoarthritic joints with increasing frequency. It's not universally accepted that the disorder always involves inflammation, however. If inflammation does occur, it may arise from damage to the synovium that lines the inside of a joint capsule.

The synovium is also known as the synovial membrane or the synovial lining. It covers the inside of the capsule surrounding a joint and produces synovial fluid, which nourishes the articular cartilage.

Inflammation of the synovium is called synovitis. In osteoarthritis, synovitis is thought to be generated when broken pieces of articular cartilage — and broken pieces of bone spurs, if they form — irritate the synovium. However, this doesn't explain all cases of osteoarthritis inflammation.

Researchers have been puzzled by the fact that in some cases of early osteoarthritis, synovitis has existed without cartilage breakdown and without bone spur formation. This suggests that the stimulus for the inflammation of the synovium comes from elsewhere.

The Significance of the Complement System

There is additional evidence that inflammation may be a cause of osteoarthritis instead of (or as well as) a result of the disease. A research team at Stanford University in the United States has shown that osteoarthritis may develop due to a malfunctioning complement system.

The complement system is part of the immune system. It's normally activated to help other components of the immune system fight infectious bacteria and viruses that have entered the body. It "complements" the action of the rest of the immune system.

The complement system consists of proteins that take part in a series of reactions known as the complement cascade. The process ends with the activation of a special complex of proteins called the membrane attack complex. This complex kills cells by creating holes in their membranes. This is very useful if a cell that is being attacked is a bacterial cell.

Although the complement system is helpful in the fight against harmful microbes, it's dangerous for healthy cells, since its function is to destroy cells. Therefore, the body makes control proteins that act as brakes for the complement cascade.

A representation of the membrane attack complex formed by the complement cascade; the letters and numbers represent proteins

A representation of the membrane attack complex formed by the complement cascade; the letters and numbers represent proteins

The Complement System in Osteoarthritis

The research carried out by the Stanford scientists suggests that the first step in the development of osteoarthritis is damage to a joint. As a result of the damage, the complement system is activated.

By extracting and analyzing joint fluid from people with and without osteoarthritis, researchers have found that people with osteoarthritis have an excessive number of proteins that accelerate the complement cascade and a low level of the proteins that stop the cascade compared to the levels in people without osteoarthritis. The researchers believe that in susceptible people the complement system attacks the injured joint, causing inflammation and damage to the articular cartilage.

The Possible Role of Cytokines

Cytokines are molecules that act as chemical messengers in the body. One group is known as pro-inflammatory cytokines. As mentioned earlier, inflammation can be useful, but an excessive amount can be harmful.

Researchers have found inflammatory cytokines in the synovial fluid of osteoarthritic joints. It's not yet certain whether the cytokines play a role in causing osteoarthritis or whether their presence is a consequence of osteoarthritis that is primarily triggered by another cause. The cytokines may make the disease worse when they are present, even if they weren't its primary cause.

The nociceptors mentioned in the quote below respond to harmful stimuli. They are often described as pain receptors because they trigger the sensation of pain when they are stimulated. Chemokines are a group of cytokines.

• Osteoarthritis is a chronic and painful disease of synovial joints.

• Osteoarthritic joint tissues produce and respond to cytokines and chemokines.

• Cytokines promote joint destruction and directly activate innervating nociceptors.

— Rachel E. Miller, Richard J. Miller, and Anne-Marie Malfait via the NIH

Steps That May Help to Prevent Osteoarthritis

It may be possible to prevent, delay, or at least weaken osteoarthritis. Since the condition often develops due to an injury to a joint, it's very important to try to reduce injuries and to treat them properly if they do happen. Joint degeneration may not be noticed until years after an injury. Although there does seem to be an inherited tendency to develop osteoarthritis in some people (as there seems to be in my family), everybody can reduce their risk of joint degeneration by taking some precautions. Here are some tips recommended by experts.

  • It's known that weight gain increases the risk of hip and knee arthritis, since there is increased force exerted on the lower body joints as the person moves. Maintain a healthy weight to reduce the chance of osteoarthritis developing.
  • Exercise to strengthen the muscles around a joint to reduce the chance of injury
  • Avoid repetitive exercise that stresses a joint.
  • Maintain good posture to protect certain joints from pressure.
  • Do warm-ups before participating in sports.
  • Participate in a variety of exercise activities that emphasize the use of different muscles and joints.
  • Start a new physical activity carefully, gradually increasing the intensity.
  • Wear safety equipment if necessary during an activity, such as knee pads for inline skating.
  • Use proper body mechanics when lifting weights to avoid injury
  • If you are injured, get proper treatment. Wait for the injury to heal completely before returning to the activity that caused the injury.

The condition known as "inflammatory osteoarthritis" affects the finger joints and does involve inflammation. Swelling and pain in the fingers may be sudden. Despite its name, the condition is neither rheumatoid arthritis nor regular osteoarthritis.

Some Common Treatments for OA

At the moment, the main treatment for osteoarthritis seems to be the use of pain- relieving medications such as acetaminophen (paracetamol) or ibuprofen. These may help remove pain for a while but don't stop the progression of the disease. Anyone who has to use pain relievers more than occasionally should consult a doctor.

Creams are available that relieve discomfort temporarily when placed on a joint. Some people find that the application of cold or heat makes their sore joints feel better. Doctors may prescribe more powerful medicines than over-the-counter ones. They may also inject potentially helpful substances into a joint, such as corticosteroids or hyaluronic acid.

Physical therapy may be helpful for osteoarthritis in some parts of the body, and so may specific joint exercises. These exercises must be done with medical guidance in order to improve the function of the joint instead of making it worse.

Dealing With the Disease in the Future

The Stanford University researchers hope to find ways to stop the complement cascade in joints in order to end inflammation. This may be tricky because anything that stops the complement cascade may also increase our susceptibility to bacterial and viral infections. If researchers can find a way`to hinder the complement system only in damaged joints and nowhere else in the body they may have an effective way to prevent osteoarthritis, or at least to slow its progression. Understanding the role of cytokines in OA and finding a way to control them may also be helpful.

Since the incidence of osteoarthritis seems to be increasing in many countries, researchers are trying to understand the disease better in order to create improved treatments. Better treatments would be appreciated by many people.


  • Osteoarthritis facts from the NIH (National Institutes of Health)
  • The complement system and osteoarthritis from Stanford University
  • Sokolove J, Lepus CM, Role of inflammation in the pathogenesis of osteoarthritis from Therapeutic Advances in Musculoskeletal Disease
  • Rachel E. Miller, Richard J. Miller, and Anne-Marie Malfait, Osteoarthritis Joint Pain: The Cytokine Connection from the National Institutes of Health
  • Inflammatory osteoarthritis information from the Arthritis Foundation

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

© 2012 Linda Crampton


Linda Crampton (author) from British Columbia, Canada on December 22, 2015:

Thank you very much, Bill. I hope you stay free of OA. I hope you have a great Christmas and New Year, too!

Bill De Giulio from Massachusetts on December 22, 2015:

Great information Linda. I sure hope I don't have to face this and so far so good. I try to stay as active as possible but it's interesting to know that injuries can lead to OA. Have a Merry Christmas and a Happy New Year.

Linda Crampton (author) from British Columbia, Canada on August 30, 2012:

Thank you very much, unknown spy! I appreciate your visit.

DragonBallSuper on August 30, 2012:

you did a great job on this hub Alicia. this is a serious thing and must not taken lightly. thanks for the info!

Linda Crampton (author) from British Columbia, Canada on August 28, 2012:

Thank you very much for the comment, drbj! I appreciate it. Yes, the C.C.C. club is one I'd rather not belong to!

drbj and sherry from south Florida on August 28, 2012:

Welcome to the club, Alicia. I'm referring to the C.C.C. - the Creaky Clicking Club. My neck clicks and creaks on demand. Not painful - yet - but annoying. You have written a remarkable, complete treatise on the topic of osteoarthritis that any encyclopedia publisher would be happy to include in the volume labeled 'O.'

Linda Crampton (author) from British Columbia, Canada on August 28, 2012:

Thank you, teaches. I appreciate the comment. Although there's no guarantee that we can avoid osteoarthritis, there are certainly ways in which we can significantly reduce the chance!

Dianna Mendez on August 28, 2012:

Alicia, this is very interesting and useful, voted up and as such. Keeping healthy and exercising is such a simple remedy to this condition. I hope that others read this and follow your advice.

Linda Crampton (author) from British Columbia, Canada on August 27, 2012:

Hi, Mama Kim 8. I think I inherited my tendency to develop osteoarthritis from my mother, who had the same problem. There does seem to be an inherited component to the disorder, at least in some families. I agree with you - that toenail infection does look very unpleasant! Thanks for the vote.

Aloe Kim on August 27, 2012:

Oh my goodness! That picture of the ingrown toenail infection was horrible! The mother of all ingrowns :/ The women in my family have OA problems in the hands. I'm not looking forward to it, but maybe some of your prevention tips will help. Voted up!

Linda Crampton (author) from British Columbia, Canada on August 27, 2012:

Thank you very much for the advice, Joyce. I appreciate it.

Joyce Haragsim from Southern Nevada on August 27, 2012:

I'm glad in a sense you go as far as osteo-arthritis. That was what I was diagonise with at first then another blood test showed the Rheumatoid.

Do keep up all your blood tests, please.

Linda Crampton (author) from British Columbia, Canada on August 27, 2012:

I'm so glad that you've found a medication that helps you with your RA, Joyce! I've been told that I have osteoarthritis in my neck, but luckily it's not causing any symptoms, apart from a clicking and creaky sound at times as I move my neck. It would be very nice if scientists could find out more about rheumatoid arthritis, osteoarthritis and the other forms of arthritis, because then they may be able to find better treatments and prevention methods.

Joyce Haragsim from Southern Nevada on August 27, 2012:

Great article for all with osteo arthritis. I'm on a fairly new med that I inject for my R/A and it seems to be working very well.

Voted up useful and very interesting, Joyce.

Linda Crampton (author) from British Columbia, Canada on August 26, 2012:

Thank you so much for such a wonderful comment, Ingenira! I appreciate it very much, and I appreciate the vote and the tweet as well.

Ingenira on August 26, 2012:

Wow, this information is as good as encyclopedia or wikipedia. Thank you for all your hard work ! Excellent article. Voted up and tweeted.