Running and your knees

Norman Swan: A few years ago I had an orthopaedic surgeon on the show talking about why we in Australia have among the highest rates of knee replacement in the world. His answer was, in effect, that we were pounding our knees into dust with all the jogging that we do and that there probably is a bit of a belief around that running is bad for your knees in terms of increasing the risk of osteoarthritis, and that if you already have osteoarthritis of the knee, you should stay away from jogging. But is that true? Well, a British and Australian study aims to find the answers, and you might be able to take part if you want. With me is senior research fellow Dr Anne Grunseit, and Professor David Hunter, both of the University of Sydney. Welcome to you, Anne, and welcome back David.

Anne Grunseit: Thanks Norman.

David Hunter: Thanks very much Norman.

Norman Swan: David, want did we know before this study started?

David Hunter: I think, as you suggested, the general community perception is that running increases your risk of osteoarthritis and that in our lifetime we only have so many steps in our joints before they're going to wear out. But I think it's really important that that misconception gets put to bed, because the current best evidence would suggest that it's really important for us to be active and that running per se does not necessarily increase our risk of developing symptoms in our joints related to osteoarthritis. So I think it's really important for people to be active.

Norman Swan: Anne, David sounds very definite there. So, you don't need to do this study?

Anne Grunseit: I wouldn't say that the evidence is quite clear yet.

Norman Swan: Disagreeing with your boss here? Okay, we'll work that out later.

David Hunter: I'm not the boss Norman.

Norman Swan: Okay, fine, Anne's your boss. So what are you trying to answer here that's unanswered?

Anne Grunseit: I guess that the previous research is inconclusive insofar as some show a benefit from running on knee pain, that there doesn't seem to be evidence about progression of knee osteoarthritis radiologically, or no new knee pain. But there's other studies that show, for example, a U-shaped relationship. So those who are sedentary and those who are very active, they seem to be at more risk of developing knee osteoarthritis, whereas those in between are not so much. So it just seems that some of the…

Norman Swan: So in other words the theory might be that there is a sweet spot somewhere.

Anne Grunseit: That's right, and that's the advantage of the study that we are doing, is we are getting quite detailed information from people across the range of physical activity. So we are interested in people who are not doing much at all, we are interested in those who are running recreationally, as well as those who are running more frequently. And we are also interested in getting people across the age spectrum. So, some of the previous studies have only been conducted with select populations, say people aged over 50, or those who already have knee osteoarthritis, whereas we want to get people with knee pain, without knee pain, and from a range of physical activity levels.

Norman Swan: Of course, David, the incidence of knee pain has got very little to do with whether you've got arthritis in your knee.

David Hunter: Exactly. So about one in four adults over the age of 55 has knee pain, of whom probably about half of those actually have osteoarthritis, and many of them won't have any evidence of osteoarthritis at all. There's lots of other reasons why a person will have knee pain. That shouldn't be discouraging them at this point from being active, as Anne suggested.

Norman Swan: So how long are you going to follow people up?

Anne Grunseit: Well, we'd like to follow people up for up to 15 years, which is quite a long time. But that's not to say that those who we follow up for a shorter time won't give us good information, but that's what we are hoping for.

Norman Swan: So if somebody wanted to participate, what are you asking of them? Have they got to wear a Fitbit for the next 15 years or what?

Anne Grunseit: No, we'd like them to participate on an online survey and that we will be following up using online surveys. We have had a number of sub-studies. So this study actually started in the UK in 2015, and there have been a number of sub-studies where we did physical examinations and took bloods and so on. But this study that we are doing the boost recruitment in Australia for at the moment is just an online survey. So as long as you have access to a computer or even a mobile you can participate.

Norman Swan: Okay, we will have details on our website of how people can actually participate. So, rather than waiting 15 years, David, and you had a broad generalisation about staying active, are there specific exercises that you should or should not be doing with knee arthritis?

David Hunter: I think the main message here is one of trying to be positive and proactive. And the biggest risk factors for a person developing osteoarthritis at present in Australia are overweight and obesity, and that accounts for about 50% of a person's likelihood of developing osteoarthritis. About 20% relates to joint injury and specifically where they are talking about injuring the cruciate ligament or a meniscal injury.

Norman Swan: So that's a story which is quite interesting, which is about kids and sport and unnecessary injuries in netball or rugby and not getting the proper coaching.

David Hunter: And occupation and genes also play a role to account for the others. But I think if a person is really interested in preventing the development of osteoarthritis, it's really important they keep their weight down, they stay strong, and ideally if they can avoid injury. And that doesn't mean don't play sport, it's just play sport safely and learn how to prevent those injuries from occurring.

Norman Swan: And the genetic component?

David Hunter: So this is what's called a polygenic disease, so there's likely a number of small genes that play a role in the development of a risk profile, and they relate to the productions of proteins in joints, specifically a particular collagen which is one of the proteins that makes up the joint tissue itself.

Norman Swan: And is it you and Anne or both of you are doing work on supplements, like glucosamine?

David Hunter: Exactly, yes. So about half of the people in the population who have osteoarthritis at the moment are taking supplements, many of which have good evidence to suggest they don't work. But some of them have some evidence, albeit from poor quality trials, to suggest that they do work. So we are really interested in seeing if we can generate a better evidence base, in this particular instance, about the use of supplements in hand osteoarthritis through a study called the RADIANT Study, which we are in the process of recruiting for. And so if people are interested, the website is tinyurl.com/RADIANTstudy. And hopefully we can also put that on the website, Norman.

Norman Swan: Anne, what's interesting here is that osteoarthritis of the hands, it's obviously not weight-bearing and it can be related to obesity and is a signal of a very peculiar kind of…well, not peculiar but a common form of osteoarthritis that may be quite different.

David Hunter: Yes, so generalised osteoarthritis is, as you suggest, very common, Norman, and interestingly weight plays an important role in predisposing a person to the development of that as well, so it's not just about bearing weight on your hands, but likely circulating inflammatory molecules that play a role in predisposing to hand osteoarthritis, and those inflammatory molecules likely come from fatty tissue.

Norman Swan: Anne, we've got tens of thousands of Radio National Health Report listeners, how many are you looking for for the study?

Anne Grunseit: We've already got 250 from our first recruitment, we'd like to have 1,500 in total. So I'm hoping that there is another 1250 people out there who would like to participate.

Norman Swan: There's bound to be. Thank you very much to you both.

Anne Grunseit: Thank you.

David Hunter: Thanks so much Norman.

Norman Swan: Dr Anne Grunseit is a senior research fellow at the University of Sydney where David Hunter is Professor of Rheumatology and Medicine.