Picture: File A study has found that arthritic knees is a highly preventable condition

THE number of people with arthritis of the knee has doubled since the Second World War – with sedentary modern lifestyles to blame, research suggests.

While it is often thought the condition is caused by ‘wear and tear’ and old age, a study has found that arthritic knees is a highly preventable condition.

Rather than being caused by the joint ‘wearing out’, the research suggests inactivity is the likely cause for the 100 per cent increase in knee arthritis.

Researchers analysed more than 2,000 skeletons from cadaver and archaeological collections spanning more than 6,000 years to show how cases have soared in the past seven decades.

Arthritis is readily detectable on skeletons because there is a shiny, glassy finish on the knee bones – caused when they rub together after the cartilage has worn out.

Professor Daniel Lieberman, of Harvard University in Boston, said: ‘The most important comparison is between the early industrial (1800s) and modern samples.

‘Because we had data on each individual’s age, sex, body weight, ethnicity and in many cases, their occupation and cause of death, we were able to correct for a number of factors that we considered important. So using careful statistical methods, we are able to say that if you were born after the Second World War you have approximately twice the likelihood of getting knee osteoarthritis at a given age or BMI [body mass index] than if you were born earlier.’

It also exposed the idea that knee osteoarthritis is now widespread because of more obesity and longevity as a myth – by controlling for factors such as weight – as measured by BMI.

Dr Ian Wallace, also of Harvard in Boston, said: ‘We were able to show, for the first time, this pervasive cause of pain is actually twice as common today than even in the recent past. But the even bigger surprise is it’s not just because people are living longer or getting fatter, but for other reasons likely related to our modern environments.’

Osteoarthritis is the most common form of arthritis, blighting the lives of 8.5million Britons.

The study, in Proceedings of the National Academy of Sciences, said the condition is responsible for more disability than almost any other musculoskeletal disorder.

Professor Lieberman said: ‘Understanding the origins of knee osteoarthritis is an urgent challenge because the disease is almost entirely untreatable apart from joint replacement. And once someone has knee osteoarthritis it creates a vicious circle. People become less active which can lead to a host of other problems and their health ends up declining at a more rapid rate.’

The researchers hope the finding will change the popular perception of it as an inevitable consequence of ageing and shift concentration on prevention – just like with cardiovascular disease.

Professor Lieberman said: ‘There are a lot of well-understood risk factors for heart disease so doctors can advise their patients to do certain things to decrease their chances of getting it.

‘Knee osteoarthritis belongs in the same category because it’s evidently more preventable than commonly assumed. But more needs to be done to figure out its causes.’

© Daily Mail