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Discover the effects of knee osteoarthritis around the world

9th January 2018

Osteoarthritis is generally believed to be the biggest cause of disability in older adults. As such, it affects millions of people and costs governments billions of pounds in treatments.

Worldwide, an estimated 10%-15% of all adults aged 60 and over have some degree of osteoarthritis (often abbreviated to OA).

In Britain, more than 8 million people - 33% of people aged over 45 years, plus 49% of women and 42% of men aged 75 and over - have been treated for OA. An estimated 4.7 million of those affected have arthritis of the knee.

So it is widely recognised as one of the biggest drains on the NHS, as well as being a cause of pain and misery for millions of people across the globe.

But just what is osteoarthritis, what causes it, how is it treated, and do people in certain countries develop it less than in others?

Diagram showing the stages of osteoarthritis of the knee Diagram showing the stages of osteoarthritis of the knee

Let’s take a look at the facts

Osteoarthritis is a very common condition which causes joints to become stiff and painful. It can affect all the joints in the body but is most likely to develop in the knees, hips and in the hands. Symptoms include swelling, redness, pain and stiffness in the affected joint, which usually lead to reduced movement and, in the worst cases, the inability to carry out everyday tasks. In the case of OA of the knee and hip, for instance, it can lead to difficulty in walking.

The severity of OA differs from person to person, and some people only ever experience mild symptoms which are sporadic in nature. Others suffer from continuous symptoms which seriously restrict their ability to cope with everyday life.

Osteoarthritis is just one type of arthritis with rheumatoid arthritis (RA) being the other most common type. OA differs from RA, which is an autoimmune disease, in that it is primarily caused by wear and tear on the joints, which is why it is more commonly found in older people. It occurs when the use of the joints leads to the protective cartilage at the end of bones breaking down. This sometimes results in the development of bony growths, which cause the joints to swell.

It is not known what causes OA, but certain factors, such as being overweight, overuse and injury and just plain old getting older, are known to increase your likelihood of developing it. Genetic factors also play a part - a family history of OA increases your chance of getting it yourself.

Diagnosis of OA usually includes an examination of the affected joints, plus questioning about symptoms and other factors. Your doctor will probably be able to diagnose the condition without any invasive tests, depending on your answers to certain questions, such as whether your joints are stiffer in the mornings, or whether the pain increases after exercise. If there is any doubt about the diagnosis, your doctor may ask you to go for blood tests or x-rays, mainly to rule out other possible causes of the symptoms such as RA or a fracture.

Doctor inspecting an x-ray of a knee

Unfortunately, there is currently no cure for OA, but it can be treated and may improve over time. Most treatments concentrate on easing the symptoms. They can include pain relief, regular exercise, physiotherapy, and the use of joint supports to reduce strain. If you are overweight, your doctor may encourage you to lose those extra pounds, as being heavier puts an increased amount of strain on your joints. If your OA is particularly severe, or it is restricting your everyday activities to a high degree, other, more invasive treatments may be offered. These include surgery to repair, strengthen or even replace the affected joint (knee or hip replacement).

So those are the basic facts about osteoarthritis. But what about those well-known ‘facts’ about warmer, drier weather being better for your OA than wetter, colder conditions? Is it true that people in warmer countries don’t get OA? How about the fact people with OA say they can tell when it’s going to rain because their symptoms get worse?

Well, some of these old wives’ tales, like most, are rooted in fact. Recent studies have indeed shown that there seems to be a relationship between the severity of OA symptoms and the weather. Recent research suggested that people with OA tend to feel less pain when the weather is dry and warm. According to the Arthritis Foundation in America, some studies have shown a direct relationship between the barometric pressure and arthritis pain. A 2014 study of a couple of hundred patients with OA in the hip seemed to support the idea that barometric pressure and the humidity related to it can influence symptoms. Another study suggested that each 10-degree drop in temperature was linked with an incremental pain increase, and that a rise in barometric pressure also triggered an increase in pain.

Most experts agree, then, that drier, warmer weather results in less OA pain, while wetter, colder weather can lead to an increase in pain. So there may well be some truth behind the belief that retiring to Spain would help ease your symptoms. However, people throughout the world get arthritis - millions of people are affected in warm and dry countries, just as they are in wetter climes, such as the UK. You are no less likely to get OA if you live in the desert.

Medical experts overwhelmingly agree that wet weather does not cause arthritis and those living in wetter countries are not more likely to develop the condition than those in drier ones. Moving to a warmer climate will not cure your OA, or stop you getting it in the first place, although it may well help ease the pain a little if you do have it.

It is thought that a change in humidity could be having an influence on the tissues in the joints, causing them to expand or contract, which results in an increase in pain. Other experts think the lower temperatures increase the stickiness of the fluids which lubricate the joints, making them more likely to cause pain. There is also a theory that the change in pain levels is simply down to the affect the warmer weather has on our mood - that people are more likely to be affected by pain when the weather is gloomy because it affects our overall outlook. This theory, however, has not been supported by research.

Hiking in the hills

So what can you do if, like most of us in the UK, you live in a largely wet climate? Moving to a warmer country is not for everyone, even if they can afford it. Not everyone wants to retire to the Mediterranean (though it would be nice).

Medical practitioners advise people living in wetter climates to ensure they stay warm and dry as much as possible when the weather is bad. This could involve wearing several layers to ensure you always stay at a comfortable temperature, and keeping the heating at a moderate level to make sure your house is always warm.

They also advise people with OA not to fall into the trap of staying indoors by the fire when the great British weather descends - instead, getting out and about, taking moderate but regular exercise, is more likely to keep you moving.

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