Find out all about the causes of arthritis in the knee

Arthritis in the knee occurs when there is “wear and tear” of the bones and cartilage in the knee. Resultant friction on the joint causes pain, stiffness and disability. 

Arthritis may occur throughout the knee or just on one side of the joint, most commonly on the inner side.  It can range from mild to severe and knee arthritis symptoms often fluctuate.

Approximately 11% of people over 64 years of age have arthritis in the knee.  There is usually no specific cause of arthritis but there are a number of factors which have been found to be linked with the condition. 

Here, we will look at the most common of these factors. 

Common Causes of Knee Arthritis

1) Aging

X-ray of arthritis in the knee compared to a normal knee joint.  Note the loss of joint space

Arthritis is related to, but not caused by aging, most commonly affecting people over 65. As we age, our bones become more brittle, our muscles often weaken, and the body becomes less efficient at healing itself. 

As a result, the cartilage and bone is more prone to damage and wear and tear, which can lead to arthritis in the knee.

2) Gender

Women are twice as likely to develop arthritis in the knee as men. The most likely reason for this is hormone levels affecting the cartilage and bone.

3) Weight

Studies have shown that osteoarthritis is three times more likely in people who are overweight (BMI over 27).  The more we weigh, the more weight goes through our bones, and therefore the more likely that the cartilage will get worn away.

It is not as simple as saying that if you are overweight you will get arthritis in the knee and if you are thin you won’t, but there is a direct correlation between the two.

4) Previous Injury

If you have injured your knee joint in the past e.g. suffered from a meniscus tear, you are more likely to develop arthritis of the knee.  This is due to changes in the bones and cartilage from the initial injury e.g. a broken bone heals but it will never be exactly the same as it was before.

Knee cartilage in particular is very slow to heal as it has a poor blood supply making it prone to wear and tear and thus arthritis.

5) Previous Surgery

If you have had to have part of your cartilage removed in the past (known as a menisectomy), you are more likely to develop arthritis in the knee as the cartilage never regrows, which puts more pressure and friction through the bones.

6) Flat Feet

Flat feet are a common feature in those suffering from arthritis in the knee

Some doctors and podiatrists believe that having flat feet increases the incidence of osteoarthritis of the knee. 

This is thought to be due to the changes in the way the forces are directed through the joint due to the altered foot position, increasing the wear on parts of the knee – usually the inner side.

7) Genetics

While we don’t fully understand the link between genes and arthritis, a link definitely exists. One example of this is that our genes may affect the quality/quantity of our cartilage (some people are born with amazing cartilage, others like me aren’t).

Up to 60% of cases of osteoarthritis are thought to be linked with genetics.

The Arthritis Vicious Circle

Arthritis in the knee often causes a vicous cycle to develop

A vicious cycle often develops with arthritis knee pain. Arthritis causes pain so you stop moving the knee as much.  Then as a result the knee gets stiffer and you lose more movement. 

Then when you try and move the knee, it hurts more, so you stop using it and the cycle continues.  The same goes for the strength of the knee.

If activities start feeling painful, we tend to avoid them, but then the muscles get weaker. As a result they can’t support the joint and more weight ends up going through the bones rather than the muscles and things get more painful. Yet another vicious cycle. 

This is why exercises are one of the best arthritis treatment options.  Muscles stay strong by being used. 

People often find they go through good spells and bad spells with arthritis in the knee. Some attribute it to the weather. Stress and tiredness often makes things worse.