Daily Life

The secret to keeping healthy knees for life

So, what's behind the epidemic of dodgy knees that has seen a 32 per cent rise in the numbers of knee replacements in Australia over the past decade?

Not just "wear and tear" and "getting older", which are the usual explanations for the osteoarthritis that strikes so many of us. Instead, it's time to recognise that carrying too much surplus fat can harm joints by producing inflammatory chemicals that can damage cartilage on the inside, Melbourne researcher Professor Flavia Cicuttini​ says.

Take action now to prevent knee damage later.
Take action now to prevent knee damage later.  

"We need to get people talking about this. Body fat isn't inert – it's very active tissue that produces inflammatory molecules that have been shown to damage joints. This means that if you're 20 kilos overweight, it's worse than if you're just carrying 20 kilos of concrete – you're carrying 20 kilos of metabolically active tissue that's doing extra damage to the joint," says Cicuttini, who heads Monash University's Musculoskeletal Unit. "We know that obesity is a strong risk factor for osteoarthritis in the hands, but we don't walk on our hands, so the fact that obesity loads the joint can't be the whole explanation."  

Writing in the Medical Journal of Australia last week, she stressed the importance of taking action to prevent the small yearly increments of weight gain that turn into bulky bodies at mid-life.  

"It's not as if we go to bed and wake up 15 kilos heavier the next morning. The evidence is that many Australians gain a small amount of weight, about 0.7 kilos, per year. Over 10 years, that adds up. We wait until there's a problem and then try to address it, but it's easier to prevent small amounts of weight creeping on when we're younger than it is to try and lose a lot of weight later in life," Cicuttini says.

It's an especially important message for anyone who's had a knee injury, such as a torn meniscus or cruciate ligament, which can fast-track knee osteoarthritis, she says.

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As health problems go, knee osteoarthritis might not have the same scary ring to it as cardiac arrest, but when sore knees make physical activity painful, it has implications for preventing and managing other chronic conditions such as heart disease and type 2 diabetes, which can be improved by regular exercise, she points out.

"The holy grail of osteoarthritis is finding a way to protect cartilage. We don't have a medicine that will do this, so anything we can do to help prevent damage to the cartilage" is helpful, Cicuttini says.

"We would still have osteoarthritis even without obesity, but there would be much less of it."

Besides keeping excess weight off, what can we do now to lower the risk of painful knees later?

Avoid sitting for long periods and be as physically active as possible, says Alex Lawrence, industry development officer for Exercise and Sports Science Australia, the professional body of accredited exercise physiologists.

"The body hasn't evolved to be still. We know that exposing bodies to repetitive strain isn't good and sitting for long periods is the equivalent of a constant repetitive strain," he says. "Regular exercise is protective against osteoarthritis, but some people will be predisposed to the problem, even though they do everything by the book. We're all different and many people have movement impairment that they have developed over time, such as a foot that rolls inwards that can expose the knee to unwanted stresses and set them up for knee osteoarthritis later on."

That's where an assessment by an accredited exercise physiologist could help by checking for any biomechanical problems that might increase the risk of osteoarthritis later, but could be improved by specific exercises, Lawrence says.  

Strength training can help protect knee joints in two ways: by improving the strength of lower body muscles that help support these joints and by helping to promote a leaner body, he adds.  But if you're a beginner, it's important to get expert advice in the correct technique to avoid any injuries.

As for recreational running, although some studies have found it reduces knee problems, it's important to go about it the right way – starting off slowly if you're a beginner, wearing appropriate shoes and including strength training, Lawrence says.

Had knee pain for three months or more? If you live in Melbourne and are aged between 40 and 70, you might be interested in taking part in a trial of a new treatment for knee pain at Monash University. For more information, go to the Knee Pain Study