January is that time of the year when thoughts turn to waistlines. Which is natural, because most of us find it rather difficult not to overindulge at Christmas: cold winter nights and excellent food go together like, well, brandy butter and Christmas pudding.
But as a new year dawns and the resolutions start to come out of hibernation, this is also a good time to reassess – to think again about our lifestyles and, in particular, the impact that weight can have on health. Perhaps there’s something in the air; this time last year the National Obesity Forum ran a useful awareness week to coincide with the post-Christmas health push
So… does being overweight affect the knees?
The short answer is: yes it does. When it comes to load-bearing, our knees have to deal with more pressure than most parts of the body. This is particularly true during movement: the knee joints act as fulcrums, which means our leg muscles need to generate a lot of power to overcome the force of the weight above them. As I pointed out in my blog last month, this is even more pronounced on steps. When you walk up or down a flight of stairs, the force of bodyweight going through your knees will be multiplied by a factor of six. That’s a lot of extra force!
What kinds of knee problems does obesity cause?
The main impact of excess weight is on cartilage. Cartilage is the rubbery tissue that lines the joints and keeps them moving smoothly. It’s a tough material, but not bulletproof. Under the strain of excess weight, it can split and ‘delaminate’. That in turn can lead to osteoarthritis, where the bones rub against each other and the joints become increasingly swollen and painful (Click on osteotomy)]. So obesity increases the wear-and-tear that can lead to osteoarthritis.
How much weight is too much weight?
This is a difficult one to answer, since the rate at which your knee cartilage wears away is related to the cartilage you’re born with. Some people have very strong collagen in their cartilage, which makes their joints more naturally resistant to wear-and-tear. Others aren’t quite so fortunate. In either case, certain types of repetitive activity will put more strain on joints than others – ladder work or long-distance running are two obvious examples. Another problem with obesity is that it can limit access to surgery; some NHS groups require patients to have a body mass index (BMI) of 30 or under before they can be referred for routine operations. If a patient in that situation has knee surgery taken off the table (so to speak), it can create a kind of vicious circle.
What can I do about it?
The good news is that you can make a big difference to your knees with small lifestyle changes – and now is the ideal time to start. In clinic, I take a ‘soft’ approach to weight loss. We see quite a few patients with high BMIs at Chris Bailey Orthopaedics, and very often they’ve heard all the weight warnings many times over before they come through the door. So I prefer to focus on the positives. You can make a huge difference to excess joint strain by losing a small amount of weight. Just take it slowly and build up the exercise: swimming and cycling are particularly good, since they put less pressure on the joints. Why not think about signing up for a class today? When it comes to knees, a little goes a long way.