Norman swan: Well, we’re going to talk about knees, but this one’s for you too, because I’m trying to help you avoid having to talk about your knees in 20 years.
Tegan Taylor: Okay.
Norman swan: The number of knee replacement surgeries pre-Covid has been increasing in Australia at just under 3% a year, so it’s 27% in a decade. In 2021, more than 68,000 knee replacements were reported to the National Joint Replacement Registry. And for the most part, osteoarthritis was the reason for getting a knee replacement. Now it’s common knowledge that knee osteoarthritis is more common the heavier you are, but not many studies have looked at how you got to that point in middle age and the impact of your weight gain trajectory. In other words, how you’ve gained weight over the years. This isn’t you, Tegan, these are other people of course.
But a study that tracked the diet and lifestyle of more than 24,000 Melburnians from early adulthood to early 60s showed that one of the benefits of actually linking them to the National Joint Replacement Registry, going back to linking of hospital data, and so on. of it, that if they could have changed the steady weight of pounds and shifted their trajectory down those years, one in three knee replacements could have been avoided, saving $373 million a year. Professor Flavia Cicuttini is Head of Rheumatology at Alfred Hospital in Melbourne and was a senior investigator on the study.
Flavia Cicuttini: We looked at patterns of weight gain, and we found six different patterns of weight gain from about age 18 to 21, through the mid-60s. And for each of those patterns, we looked at the number of joint replacements in that group. Now, we asked, what would happen if everyone who was in one of the weight gain patterns lost weight by one? So we didn’t try to get people all to a normal, healthy weight, just a trajectory down. And what we found is if you did that and just didn’t gain as much as you’d like, we’d end up avoiding about 30% of knee replacements, which would cost $370 million.
And if we look at what weight we are talking about, we are talking about a weight difference of 8 to 12 kilos over 40 years. But what we also know is that people gain an average of two to three pounds a year, and that’s a very relentless rate of weight gain. You know, people don’t suddenly wake up one day with huge amounts of weight, it’s this very relentless weight gain that happens. So it’s this slow weight gain over many years that we don’t consider and focus on…
Norman swan: Do we understand the causes of that weight gain?
Flavia Cicuttini: I don’t think we do. But if you turn it around and ask the question, how many calories or what kind of difference in energy balance are we talking about? It’s really only seven kilocalories per day, or 30 kilojoules, which, to put it into perspective, is an extra 10 minutes of walking per week, or two fewer chocolates every two weeks. What we see even in our patients with knee osteoarthritis, when we did a survey, there wasn’t a person around who didn’t know that they’re carrying a little bit too much weight and should try to lose it. But what we also see is you see someone in their early 40s who might have some knee pain, maybe put on an extra two or three pounds, and then they’re advised to lose weight, and we know people don’t. t tend to lose weight. And so what we do is then 10 years later we see someone who has a little more knee pain, and then we say, well, you know, you need to lose weight. But in the meantime they have gained another five kilos. And the problem is that once you carry a lot of weight, you already have the joint damage and you can’t reverse that damage. And the data also says you need to lose about 7.5% of your weight to get a clinically significant reduction in knee pain. Now, I’m not suggesting that people shouldn’t lose weight, but we already know that’s not something people can easily do.
Norman swan: So you are arguing for interventions to stop the kilo flu.
Flavia Cicuttini: My point in that is that potentially is an achievable goal, I feel like we’re playing while Rome burns as we continue to focus on weight loss. But the very people we advise to lose weight and push this idea of losing weight through, then slowly gain weight. And I don’t think there’s a realization that even if you’re carrying a few extra pounds, if you turn around and stop gaining weight, if the whole community stops gaining weight, we’d be pounds better off.
Now, I think the nice thing about our study is that it actually has a dollar value on the potential implications of tackling this kilo creep. And one of the main issues with the idea of the kilo-creep, it’s not mutually exclusive for weight loss, it recognizes that the way we live is different than it used to be. But instead of saying “you have to be slim, you have to be slim,” we’re just saying, yes, you should lose weight if you can, but whatever you do, don’t gain weight.
So one of the most important things has to be the realization that this is an achievable goal. And I think it fits with the recent Australian of the Year now focusing on teaching people to love and appreciate their bodies, and focus on health. Because I think one of the other problems is that our focus on boosting weight loss when we know it’s not successful is that we tend to keep shaming people who don’t lose weight.
For example, we know that 50% of obese women have not come to an appointment if they thought they were going to be weighed. What I’m suggesting is that while we’re telling people to lose weight, no one is saying think about strategies you can use in your own life to stop this slow-burning kilogram flu. For every kilo you carry, you put four kilos on the knee. But fat is also metabolically active, so you’re effectively loading up a squishy joint.
What we’ve found clinically is that when we advise people that not gaining weight is really a worthwhile goal, people’s eyes light up because there’s finally something they can potentially do.
Norman swan: Flavia, thank you very much for joining us.
Flavia Cicuttini: Thank you.
Norman swan: Professor Flavia Cicuttini is head of the Musculoskeletal Group at Monash University.