arthritis on the knee

What is Arthritis?

Arthritis is basically defined as an inflammation of one or more joints. There are many different types of arthritis that exist and you may be affected by more than one at once.

We will mention here the most common forms of arthritis as well as symptoms indicating that you might be having arthritis. We will not get into details on each type of arthritis as that may cause this article to be ridiculously long.

Most people think arthritis affect only old people, but it is not the case. Anyone can have arthritis, including children.

Let’s first talk about what makes up the joint before going into details on types of arthritis.

What makes up a Joint?

Your joint is made up of two bones that join together. The bones don’t really touch each other, instead there is a cartilage tissue at the top of each bone head to prevent rubbing of bones during movement which can cause erosion of the bones.

Another thing found in each joint is the synovial fluid. The fluid is found inside the joint cavity to keep it moist and to nourish the surrounding structures found inside the join.

Joint anatomy
Joint anatomy

As you know that the two bones that meet do not really touch. There are fibrous tissues surrounding the joint called ligaments. Some ligaments, such as Anterior Cruciate Ligament (ACL) and Posterior Cruciate ligaments run inside the joint attaching one end to the 1st bone and the other end to the 2nd bone.

The inside of the surrounding ligaments produce the synovial fluid.

What has been described so far is how Synovial joints are structured.

There are three types of joints that exist

  • Synovial joints such as knees, elbows, fingers and toes, shoulders, ankles and hips.
  • Cartilaginous joints do not contain any synovial fluid and are immobile or have limited mobility. They are found in the spine connecting the spine bones and in the pelvic bones.
  • Fibrous Joints are found on the skull bones

Now, when you have arthritis, it simple means that there is inflammation or something wrong in one or more of these joints.

Types of Arthritis

There are many types of arthritis caused by different factors which are not related at all.

They can be divided into:

  • Monoarthritis
  • Polyarthritis
  • Migrating arthritis or Reactive arthritis


Mono-arthritis means arthritis affecting one joint in the body.

The two most common forms or causes of Monoarthritis are:

  1. Septic arthritis or infectious arthritis
  2. Gouty arthritis simple known as Gout.

Septic arthritis is caused by an infection that finds its way inside the joint and cause inflammatory response. It is common if you have an open wound near or on the joint itself.

It is more common in children who like to play and get a bruise on the knees after falling. But adults do get it as well, especially if they have weak immune system such as those who have Diabetes Mellitus, HIV, and Cancer.

Gouty Arthritis, also known as Gout is one of the most painful forms of arthritis out there. Here you have uric acid crystals that form inside the synovial joints. There are many causes of excess uric acid, including some drugs used to treat High blood Pressure, Alcohol, and starvation. We will not dwell much on it in this article because it is a long topic that requires its own coverage.


Polyarthritis is a type of arthritis in which many joints are affected at the same time. The joints affected may be symmetric or asymmetric.

An example of symmetric joints is when you have both hands and both wrists or shoulders affected at the same time.

When the distribution of arthritis is asymmetric, it’s like, for example when you have an elbow affected on one side and a knee on the other. This pattern is seen in a type of arthritis called osteoarthritis.

Below is a list of common types of polyarthritis:

  • Rheumatoid Arthritis
  • Osteoarthritis
  • SLE ( known as Systemic Lupus Erythematosus in full)
  • Juvenile Idiopathic Arthritis which affects children and involves many joints
  • Psoriatic arthritis

As you can see from the list above, there are many types of polyarthritis that exist. It is therefore important that you do not diagnose yourself at home if you have joint pains.

Now look at signs and symptoms of arthritis.

Signs and symptoms of Arthritis 

Joint pain of arthritis

The common symptom of arthritis is Arthralgia!

Arthralgia is a medical term for painful joint or joints. Do not confuse it with inflammation of the joint called arthritis.

The pain is accompanied by swelling and redness of the affected joint. The movement of the joint is also limited by pain and swelling.

Those with Rheumatoid arthritis may also develop a deformity called ‘swan neck deformity”.

If you also have fever, it may be a sign that you have septic arthritis.

You should seek medical help as soon as possible if you have any of the following:

  1. Joint pains for more than a week
  2. Severe  pain on the joint or swelling after an injury or on the side with a small bruise
  3. Joint pains in a child needs medical evaluation as early as possible
  4. Having joint pains and someone at home with arthritis as you may have inherited a form of arthritis that is genetically passed.

Who is at Risk of developing arthritis?

There are some people who are more likely to develop arthritis than others. Here are some of the risk factors:

  1. Age: Arthritis can affect people of all ages, but the risk increases with age. Osteoarthritis, for example, is more common in older adults.
  2. Gender: Some types of arthritis are more common in one gender. For instance, rheumatoid arthritis is more common in women, while gout is more common in men.
  3. Family History: A family history of arthritis, particularly certain types like rheumatoid arthritis and ankylosing spondylitis, can increase the risk of developing arthritis.
  4. Genetics: Certain genetic factors can predispose individuals to various types of arthritis. Researchers have identified specific genes associated with some forms of arthritis.
  5. Obesity: Excess weight places added stress on the joints, especially in the knees, hips, and spine. This can increase the risk of developing osteoarthritis. So if you’re Obese, it’s a risk.
  6. Joint Injuries: Previous joint injuries or trauma, such as sports injuries or accidents, can increase the likelihood of developing post-traumatic arthritis.
  7. Occupation: Jobs that involve repetitive joint movements or heavy lifting may increase the risk of arthritis, particularly osteoarthritis.
  8. Infections: Some infections can lead to reactive arthritis, an autoimmune response that can affect the joints. This includes certain bacterial and viral infections.
  9. Autoimmune Diseases: Conditions like lupus, psoriasis, and inflammatory bowel disease (IBD) can increase the risk of developing autoimmune forms of arthritis, such as rheumatoid arthritis.
  10. Diet: Poor dietary habits, especially a diet high in processed foods, sugary drinks, and red meat, may contribute to inflammation and increase the risk of developing arthritis.

It’s important to remember that having one or more risk factors does not guarantee that someone will develop arthritis, and conversely, the absence of risk factors does not guarantee immunity

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