The knee is the joint most commonly affected by osteoarthritis.
Dr Gareth Jones reveals the common mistakes that can lead to osteoarthritis – and what we can do to reduce our risk of damage.
The knee is the joint most commonly affected by osteoarthritis. It’s the largest joint in the body and carries more weight than the hips. It’s probably also our most complicated joint. All this means that, from an injury perspective, there is much more that can go wrong. It also makes the knee a difficult joint to successfully replicate and replace. It’s important to do what we can to protect them.
When it comes to knee damage, there is a genetic component. Leg shape impacts how you load the knees – most people are slightly bow legged, but others have slightly knock knees. Both issues accelerate wear on different parts of the knee joint, increasing the risk of arthritis. Genes also play a role in cartilage quality and probably in the inflammatory factors that lead to osteoarthritis. But there is still much we can do to reduce our risk of damage and the eventual need for a knee replacement.
Here are the main mistakes we make in midlife when it comes to knee health.
The number-one midlife mistake when it comes to knee health has to be putting on weight. If you see your weight going up, you shouldn’t ignore it, as there is more than enough evidence from long-term studies that show how the knee in particular is affected. Our knees are more vulnerable than the hips, as they sit lower in the body. However, losing weight will reduce that risk.
If you’re walking on flat ground, the amount of load that is going through your knee is somewhere between one and a half and three times your body weight. If you’re going up or down stairs, it can be up to six times your body weight. For someone who has gained just 10 pounds (4.5 kilograms) over the years, that is potentially 30lb more weight on their knees every time they take a step. That is significant.
When it comes to specific diet advice, there’s no scientific evidence for any foods that impact knee osteoarthritis or its progression. Vitamin D is important for general bone health, and a large number of British people are deficient in it. So it’s a good idea to take a supplement. Other than that, I’d recommend a healthy, balanced diet.
The second most common mistake is thinking: “My knees ache a bit, I’m just going to stop doing any activities”. The sedentary lifestyle leads to muscular de-conditioning, and we need muscles to help reduce the load on the joints.
More than this though, the cartilage – the smooth, shiny lining of the knee that allows bone to glide over bone without friction and pain – deteriorates in people who do no or very little exercise. Our cartilage doesn’t have a blood supply to feed it. It gets its nourishment from synovial fluid that diffuses in. Movement allows fluid to circulate and stimulates the production of more. It seems that our cartilage also needs loading and some stress to stay healthy. Cartilage responds to loading by producing different proteoglycans, which might improve its structure.
If you’re going to choose an exercise, I’d probably go for a lot of walking, along with cycling and cross training, which are gentle on the knee joint. Swimming is also good, especially swimming with a straight leg. If you can do a straight-leg front crawl, choose that over a frog-kick breaststroke, which puts a bit of extra stress on the outside of the knee.
Recreational running is also fine – there’s evidence that people who run a moderate amount have a lower risk of knee osteoarthritis than people who don’t run. If you already have mild arthritis in your knee, instinctively I’d suggest lower-impact activities. However, the one study that included this scenario found that people with early knee osteoarthritis (confirmed on X-rays) who chose to run regularly, when compared over four years to patients who did not run, did not show any increased progression in their osteoarthritis. In fact, the runners experienced less knee pain.
The current movement towards doing lots of squats and lunges with heavy weights is not good for knees. Interestingly, I’m starting to see injuries in really young people – in their mid 20s and early 30s – who’ve lost a lot of cartilage from under their kneecaps through following very high-impact, high-repetition exercise programmes such as Hyrox and CrossFit. Similarly, there’s evidence that competitive runners have an increased risk of knee osteoarthritis compared to recreational runners.
The question as to what constitutes “recreational running” versus “competitive running” is actually difficult to answer, as it varies between studies. However, there is a link between longer distance and an increased risk of knee osteoarthritis, so a three-mile run in the park would definitely be preferable to a marathon.
Muscles are important for absorbing some of the load. If they are strong, they can take some of the weight off the joint and help protect it from damage. It is the quads – the large muscle group at the front of the thigh – that are particularly important here. There are longitudinal studies that show people with knee osteoarthritis have measurably weaker quads, even before the osteoarthritis is visible on an X-ray. (This suggests that muscle weakness is not a consequence of joint damage, but a potentially modifiable risk factor that precedes it.)
Muscle strength certainly improves pain and function – not just the strength of the quads, but also the hamstrings, calf muscles, glutes and hip abductors. General strength exercises are all going to be good for this – using moderate weights or repetitions of low weights. Just don’t do 50 weighted squats in a row! It’s about moderation and finding a sensible balance.
With any injury, there’s the immediate damage, and then the long-term joint instability and inflammation, and a significantly raised risk of osteoarthritis. Look into your sport – whatever sport you are doing – and learn about its most common injury risks and how to reduce them. Personally, I love skiing, which is a very common cause of knee, especially ACL, injuries. There’s very good evidence from a successful research programme and public awareness campaign in Vermont that understanding how to reduce your risk of knee injury when skiing can make a very big difference. “Knee-friendly skiing” includes position, technique, the way you fall and your boot bindings.
General strengthening exercises are also important for injury avoidance. There are neuromuscular exercise programmes such as Nemex, a supervised eight-week exercise regime focused on making sure joints move as they should. It’s about controlling the position of the knee and where the body is over the knee. There’s good evidence that these programmes can reduce ACL injuries in young athletes (ACL injuries significantly increase the risk of developing knee osteoarthritis later). I see no reason why this wouldn’t also be the case for people in middle age.
Core-strengthening exercises, Pilates, and anything that helps with balance and your ability to avoid falling, slipping and twisting in unusual ways will help you remain injury-free – and that will dramatically reduce your risk of osteoarthritis.
A well-functioning joint is a bit like a tyre. If it has a flat spot in one part, or a stone stuck in it, it might still seem to work, but eventually, maybe even 10,000 miles on, it’s going to blow. If you experience sudden onset of knee pain after some twisting movement or injury or fall, and it doesn’t settle after four to six weeks, then that’s something to get checked. Some meniscus tears are repairable. Once, this was only done on younger people, but now, if someone has a repairable tear, irrespective of age, we should go ahead and repair it to keep that shock absorber functioning and reduce the risk of arthritis.
Other common red flags would be ACL injuries as a result of the knee sliding and rolling abnormally. If you are feeling that you can’t trust your knee, if it feels unstable going downstairs, if it’s going into a slightly abnormal position, get it checked. Don’t try to exercise on an injury, or stoically carry on as normal. Listen to your body and be guided by pain.
– As told to Anna Moore