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The simple osteoarthritis definition provided by the NHS is outlined as 'a condition that causes joints to become painful and stiff', but the mechanisms behind osteoarthritis are a lot more complicated.

It is also referred to as arthrosis, osteoarthrosis or OA and is a degenerative disease that causes the cartilage that protects the ends of your bones to wear down. This causes pain, swelling and problems with mobility.

It is older people who tend to develop osteoarthritis, with wear and tear of the joints being responsible for a lot of the damage. A number of degenerative changes can take place at the same time and one change can trigger further damage in a domino effect.

Typically, the protective fluid in the joint loses its shock-absorbing abilities, causing bones to rub against each other. This causes the bones to thicken and stick out, a symptom known as spurs. OA will also cause the capsules and ligaments, bands that hold the joint together, to thicken as extra fluid forms around the joint. The end result is swelling and the joint appears larger.

These symptoms are a result of the body attempting to repair the joint, something that can sometimes occur relatively pain free. In severe cases the cartilage can become so thin that it doesn't cover the end of the bone, leaving it exposed and consequently changing the shape of the joint due to the excessive wearing away of the bone and the presence of bony spurs. Any joint in the body can be affected by OA but the most common damage is found in the knees, hips, lower back, neck, fingers and toes.

What is osteoarthritis of the knee?

Osteoarthritis of the knee is one of the forms of the disease that can be suffered by younger people and can also be hereditary. It is associated with certain types of occupation and people who have to kneel, lift heavy weights or squat repeatedly are more likely to develop it because their knee joints are under constant pressure. Also, sports professionals and amateurs who play football or tennis or who regularly run long distances are also at a higher risk of developing this condition.

So, what is osteoarthritis of the knee pain like? Typically it will start with a niggling pain when you are exercising but will stop hurting when you rest. You may notice that the knee joint is enlarged (swelling) and that it feels warm to the touch. This is a sign that the joint is inflamed. After a while there will be some changes in how the joint moves. For many people, this starts as a mild stiffness after sitting down or sleeping at night.

The stiffness resolves as you move around at first but gets progressively worse after a period of weeks and months. Eventually, it may be difficult to get up out of a chair or to get in and out of a car. Stairs and steep slopes can be particularly challenging. You may also start to hear a cracking or creaking like sound coming from the joint when you bend your knee, especially if you are putting weight on it.

Diagnosing osteoarthritis of the knee

The diagnosis of osteoarthritis of the knee is made using a physical examination together with X-rays or MRI scans. Using this information, your doctor will be able to tell the severity of the disease and classify it into one of four stages. Stage 1 is a mild disease where there is minor wear and tear of the knee joint and some small bone spur growths. The level of pain and discomfort is likely to be minimal and it can be treated conservatively. This means that you may be advised to make lifestyle changes to reduce your weight to ease the pressure on your joints and you may be offered an exercise plan. You may also be advised to try a dietary supplement such as chondroitin to support joint health.

At Stage 2 there will be more extensive growth of bone spurs but the cartilage will still be normal and the bones of the knee joint will not rub together as you move. The fluid bathing the joint (synovial fluid) is still providing lubrication so that the joint can move normally. However, you will be experiencing some pain and discomfort at this stage. It will be most severe after you have walked a long distance or been for a challenging run.

You will also notice stiffness first thing in the morning or when you have sat down for a long time. Osteoarthritis of the knee at this stage is characterised by tenderness when you are kneeling or bending the joint. Treatment is aimed at preventing the disease from progressing and relieving discomfort. It includes weight loss, low impact exercises and strength training and avoiding squatting, jumping and kneeling. Braces may be needed to stabilise the knee and shoe inserts can realign the bones.

Stages 3 and 4 cause significant pain and impact mobility. There is a lot of friction within the joint and the cartilage and synovial fluid are significantly depleted. At this stage you may need injections into the joint or surgery and in the most severe cases this can be a total knee replacement.

For further information on the condition, take a look at the What is Osteoarthritis of the Knee guide from Arthritis Research UK, which offers a comprehensive review of the condition and how the charity can help sufferers.

What Is Osteoarthritis - Osteoarthritis Knee - OA Knee Pain What Is Osteoarthritis? - Osteoarthritis Knee

Who can be affected?

There is no direct cause of OA and almost anyone can get the condition, including children. However, you’re more likely to suffer OA if you fall under any of the following categories:

  • You are a woman
  • You are 40 years old or older
  • Your parents have had OA
  • You are overweight
  • You have had a previous joint injury
  • You are in a physically demanding job
  • Your joints have been affected by another disease, for example, gout or rheumatoid arthritis

For more information on the conditions that can cause OA, click here.

Types of Osteoarthritis

Osteoarthritis is the most common type of arthritis in the UK. Other types of arthritis that cause pain and inflammation in the joints include:

  • Ankylosing spondylitis
  • Cervical spondylosis
  • Enteropathic arthritis
  • Fibromyalgia
  • Gout
  • Psoriatic arthritis
  • Rheumatoid arthritis
  • Reactive arthritis
  • Secondary arthritis
  • Polymyalgia rheumatica

To find out how the different types of arthritis can affect your joints, take a look at our Types of Arthritis page.

Common symptoms of Osteoarthritis

The most common symptoms of OA are pain and stiffness in the joint, with some people experiencing swelling, tenderness and a grating sound when using the damaged joint.

The severity of symptoms differs from person to person with some feeling mild discomfort that can come and go and others suffering continuous debilitating pain, which can make it difficult to go about their daily activities.

If you’re showing the symptoms of OA, you should make an appointment with your GP who can diagnose the condition and prescribe relevant treatment.

What Is Osteoarthritis - Knee OA - OA Knee Pain Knee OA causes pain and stiffness in the affected knee joint

Is osteoarthritis an autoimmune disease?

Some types of arthritis are autoimmune disorders, but osteoarthritis is not one of them. The mechanism of disease in autoimmune arthritis is very different. Osteoarthritis is all about mechanical wear and tear whereas autoimmunity is caused by the body attacking its own tissues. The body’s defence mechanisms mistakenly identify the joints as a foreign substance that has the potential to do harm to the body such bacteria or viruses. This causes it to launch an attack.

The immune system plays a vital role in protecting us from pathogens and is very powerful. Sadly, when those powers are directed against the body’s own tissues it can do a lot of harm and normal healthy tissue becomes damaged. Autoimmune arthritis is characterised by an attack of self-tissues that begins in the joints and joint pain is often one of the early symptoms.

The most common type of autoimmune arthritis is called rheumatoid arthritis but juvenile arthritis and lupus are also widespread conditions. There is on-going research to try and identify the best methods of treatment and to understand how the disease arises in the first place. It is important to note that if you have been diagnosed with osteoarthritis this is a completely different type of disease and it does not involve your own immune system.

Understanding diagnosis and treatment osteoarthritis meaning

Your GP can usually diagnose OA based on your symptoms and a physical examination of your joints. However, your doctor may also ask for a blood test, X-ray or a Magnetic Resonance Imaging (MRI) scan. For more information on diagnosing OA, visit our Diagnosis page.

Even though OA is a long-term incurable condition, treatments can be prescribed to ease the symptoms, improve the condition and prevent it from getting worse. There are a number of treatment options available, including non-surgical solutions, such as exercising, bracing and medication, as well as surgical solutions, like arthroscopy, tibial osteotomy and full knee replacements.

To find out more about the different types of treatment available for OA, take a look at What are my Options?

What Is Osteoarthritis - Osteoarthritis Of The Knee - OA Knee Pain An x-ray or MRI can be used to help diagnose osteoarthritis of the knee

Useful Links

There are multiple studies available online relating to osteoarthritis.

Visit https://www.pubmed.de/gateway/nlm-pubmed/ and use the search term “knee osteoarthritis therapy” (with over 800 pages of results).

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